Rohde&Schwarz FSU, FSU-B9, FSU-B10, FSP-B16, FSU-B18 Operating Manual

...

Download

R&S®FSU

Spectrum Analyzer

1313.9646.12 – 02

Test & Measurement

Operating Manual

The Operating Manual describes the following R&S®FSU models and options:

● R&S FSU (1313.9000.xx)

● R&S FSU (1166.1660.xx)

● R&S FSU-B9 (1142.8994.02)

● R&S FSU-B10 (1129.7246.03)

● R&S FSP-B16 (1129.8042.03)

● R&S FSU-B18 (1303.0400.13)

● R&S FSU-B21 (1157.1090.03)

● R&S FSU-B27 (1157.2000.02)

The contents of this manual correspond to firmware 4.71SP5 or higher.

Muehldorfstr. 15, 81671 Munich. Germany

Phone: +49 89 4129-0

Fax: +49 89 4129-12 164

E-mail: info@rohde-schwarz.com

Internet: http://www.rohde-schwarz.com

81671 Munich, Germany

Subject to change – Data without tolerance limits is not binding.

R&S

is a registered trademark of Rohde & Schwarz GmbH & Co. KG.

Trade names are trademarks of the owners.

The following abbreviations are used throughout this manual:

R&S

FSU is abbreviated as R&S FSU.

Basic Safety Instructions

Always read through and comply with the following safety instructions!

All plants and locations of the Rohde & Schwarz group of companies make every effort to keep the safety standards of our products up to date and to offer our customers the highest possible degree of safety. Our products and the auxiliary equipment they require are designed, built and tested in accordance with the safety standards that apply in each case. Compliance with these standards is continuously monitored by our quality assurance system. The product described here has been designed, built and tested in accordance with the EC Certificate of Conformity and has left the manufacturer’s plant in a condition fully complying with safety standards. To maintain this condition and to ensure safe operation, you must observe all instructions and warnings provided in this manual. If you have any questions regarding these safety instructions, the Rohde & Schwarz group of companies will be happy to answer them.

Furthermore, it is your responsibility to use the product in an appropriate manner. This product is designed for use solely in industrial and laboratory environments or, if expressly permitted, also in the field and must not be used in any way that may cause personal injury or property damage. You are responsible if the product is used for any purpose other than its designated purpose or in disregard of the manufacturer's instructions. The manufacturer shall assume no responsibility for such use of the product.

The product is used for its designated purpose if it is used in accordance with its product documentation and within its performance limits (see data sheet, documentation, the following safety instructions). Using the product requires technical skills and, in some cases, a basic knowledge of English. It is therefore essential that only skilled and specialized staff or thoroughly trained personnel with the required skills be allowed to use the product. If personal safety gear is required for using Rohde & Schwarz products, this will be indicated at the appropriate place in the product documentation. Keep the basic safety instructions and the product documentation in a safe place and pass them on to the subsequent users.

Observing the safety instructions will help prevent personal injury or damage of any kind caused by dangerous situations. Therefore, carefully read through and adhere to the following safety instructions before and when using the product. It is also absolutely essential to observe the additional safety instructions on personal safety, for example, that appear in relevant parts of the product documentation. In these safety instructions, the word "product" refers to all merchandise sold and distributed by the Rohde & Schwarz group of companies, including instruments, systems and all accessories. For product-specific information, see the data sheet and the product documentation.

Safety labels on products

The following safety labels are used on products to warn against risks and dangers.

Symbol Meaning Symbol Meaning

Notice, general danger location

Observe product documentation

Caution when handling heavy equipment Standby indication

Danger of electric shock Direct current (DC)

ON/OFF supply voltage

1171.0000.42 - 07 Page 1

asic Safety Instructions

Symbol Meaning Symbol Meaning

Warning! Hot surface Alternating current (AC)

Protective conductor terminal Direct/alternating current (DC/AC)

Ground Device fully protected by double (reinforced)

insulation

Ground terminal EU labeling for batteries and accumulators

For additional information, see section "Waste disposal/Environmental protection", item 1.

Be careful when handling electrostatic sensitive devices

Warning! Laser radiation

For additional information, see section "Operation", item 7.

EU labeling for separate collection of electrical and electronic devices

For additonal information, see section "Waste disposal/Environmental protection", item 2.

Signal words and their meaning

The following signal words are used in the product documentation in order to warn the reader about risks and dangers.

Indicates a hazardous situation which, if not avoided, will result in death or serious injury.

Indicates a hazardous situation which, if not avoided, could result in death or serious injury.

Indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.

Indicates information considered important, but not hazard-related, e.g. messages relating to property damage. In the product documentation, the word ATTENTION is used synonymously.

These signal words are in accordance with the standard definition for civil applications in the European Economic Area. Definitions that deviate from the standard definition may also exist in other economic areas or military applications. It is therefore essential to make sure that the signal words described here are always used only in connection with the related product documentation and the related product. The use of signal words in connection with unrelated products or documentation can result in misinterpretation and in personal injury or material damage.

1171.0000.42 - 07 Page 2

asic Safety Instructions

Operating states and operating positions

The product may be operated only under the operating conditions and in the positions specified by the manufacturer, without the product's ventilation being obstructed. If the manufacturer's specifications are not observed, this can result in electric shock, fire and/or serious personal injury or death. Applicable local or national safety regulations and rules for the prevention of accidents must be observed in all work performed.

1. Unless otherwise specified, the following requirements apply to Rohde & Schwarz products: predefined operating position is always with the housing floor facing down, IP protection 2X, use only indoors, max. operating altitude 2000 m above sea level, max. transport altitude 4500 m above sea level. A tolerance of ±10 % shall apply to the nominal voltage and ±5 % to the nominal frequency, overvoltage category 2, pollution severity 2.

2. Do not place the product on surfaces, vehicles, cabinets or tables that for reasons of weight or stability are unsuitable for this purpose. Always follow the manufacturer's installation instructions when installing the product and fastening it to objects or structures (e.g. walls and shelves). An installation that is not carried out as described in the product documentation could result in personal injury or even death.

3. Do not place the product on heat-generating devices such as radiators or fan heaters. The ambient temperature must not exceed the maximum temperature specified in the product documentation or in the data sheet. Product overheating can cause electric shock, fire and/or serious personal injury or even death.

Electrical safety

If the information on electrical safety is not observed either at all or to the extent necessary, electric shock, fire and/or serious personal injury or death may occur.

1. Prior to switching on the product, always ensure that the nominal voltage setting on the product matches the nominal voltage of the AC supply network. If a different voltage is to be set, the power fuse of the product may have to be changed accordingly.

2. In the case of products of safety class I with movable power cord and connector, operation is permitted only on sockets with a protective conductor contact and protective conductor.

3. Intentionally breaking the protective conductor either in the feed line or in the product itself is not permitted. Doing so can result in the danger of an electric shock from the product. If extension cords or connector strips are implemented, they must be checked on a regular basis to ensure that they are safe to use.

4. If there is no power switch for disconnecting the product from the AC supply network, or if the power switch is not suitable for this purpose, use the plug of the connecting cable to disconnect the product from the AC supply network. In such cases, always ensure that the power plug is easily reachable and accessible at all times. For example, if the power plug is the disconnecting device, the length of the connecting cable must not exceed 3 m. Functional or electronic switches are not suitable for providing disconnection from the AC supply network. If products without power switches are integrated into racks or systems, the disconnecting device must be provided at the system level.

5. Never use the product if the power cable is damaged. Check the power cables on a regular basis to ensure that they are in proper operating condition. By taking appropriate safety measures and carefully laying the power cable, ensure that the cable cannot be damaged and that no one can be hurt by, for example, tripping over the cable or suffering an electric shock.

1171.0000.42 - 07 Page 3

asic Safety Instructions

6. The product may be operated only from TN/TT supply networks fuse-protected with max. 16 A (higher fuse only after consulting with the Rohde & Schwarz group of companies).

7. Do not insert the plug into sockets that are dusty or dirty. Insert the plug firmly and all the way into the socket provided for this purpose. Otherwise, sparks that result in fire and/or injuries may occur.

8. Do not overload any sockets, extension cords or connector strips; doing so can cause fire or electric

hocks.

9. For measurements in circuits with voltages V

> 30 V, suitable measures (e.g. appropriate

rms

measuring equipment, fuse protection, current limiting, electrical separation, insulation) should be taken to avoid any hazards.

10. Ensure that the connections with information technology equipment, e.g. PCs or other industrial computers, comply with the IEC60950-1/EN60950-1 or IEC61010-1/EN 61010-1 standards that apply in each case.

11. Unless expressly permitted, never remove the cover or any part of the housing while the product is in operation. Doing so will expose circuits and components and can lead to injuries, fire or damage to the product.

12. If a product is to be permanently installed, the connection between the protective conductor terminal on site and the product's protective conductor must be made first before any other connection is made. The product may be installed and connected only by a licensed electrician.

13. For permanently installed equipment without built-in fuses, circuit breakers or similar protective devices, the supply circuit must be fuse-protected in such a way that anyone who has access to the product, as well as the product itself, is adequately protected from injury or damage.

14. Use suitable overvoltage protection to ensure that no overvoltage (such as that caused by a bolt of lightning) can reach the product. Otherwise, the person operating the product will be exposed to the danger of an electric shock.

15. Any object that is not designed to be placed in the openings of the housing must not be used for this purpose. Doing so can cause short circuits inside the product and/or electric shocks, fire or injuries.

16. Unless specified otherwise, products are not liquid-proof (see also section "Operating states and operating positions", item 1). Therefore, the equipment must be protected against penetration by liquids. If the necessary precautions are not taken, the user may suffer electric shock or the product itself may be damaged, which can also lead to personal injury.

17. Never use the product under conditions in which condensation has formed or can form in or on the product, e.g. if the product has been moved from a cold to a warm environment. Penetration by water increases the risk of electric shock.

18. Prior to cleaning the product, disconnect it completely from the power supply (e.g. AC supply network or battery). Use a soft, non-linting cloth to clean the product. Never use chemical cleaning agents such as alcohol, acetone or diluents for cellulose lacquers.

Operation

1. Operating the products requires special training and intense concentration. Make sure that persons who use the products are physically, mentally and emotionally fit enough to do so; otherwise, injuries or material damage may occur. It is the responsibility of the employer/operator to select suitable personnel for operating the products.

1171.0000.42 - 07 Page 4

Basic Safety Instructions

2. Before you move or transport the product, read and observe the section titled "Transport".

3. As with all industrially manufactured goods, the use of substances that induce an allergic reaction (allergens) such as nickel cannot be generally excluded. If you develop an allergic reaction (such as a skin rash, frequent sneezing, red eyes or respiratory difficulties) when using a Rohde & Schwarz product, consult a physician immediately to determine the cause and to prevent health problems or stress.

4. Before you start processing the product mechanically and/or thermally, or before you take it apart, be sure to read and pay special attention to the section titled "Waste disposal/Environmental protection", item 1.

5. Depending on the function, certain products such as RF radio equipment can produce an elevated level of electromagnetic radiation. Considering that unborn babies require increased protection, pregnant women must be protected by appropriate measures. Persons with pacemakers may also be exposed to risks from electromagnetic radiation. The employer/operator must evaluate workplaces where there is a special risk of exposure to radiation and, if necessary, take measures to avert the potential danger.

6. Should a fire occur, the product may release hazardous substances (gases, fluids, etc.) that can cause health problems. Therefore, suitable measures must be taken, e.g. protective masks and protective clothing must be worn.

7. Laser products are given warning labels that are standardized according to their laser class. Lasers can cause biological harm due to the properties of their radiation and due to their extremely concentrated electromagnetic power. If a laser product (e.g. a CD/DVD drive) is integrated into a Rohde & Schwarz product, absolutely no other settings or functions may be used as described in the product documentation. The objective is to prevent personal injury (e.g. due to laser beams).

8. EMC classes (in line with EN 55011/CISPR 11, EN 55032/CISPR 32)  Class A equipment:

Equipment suitable for use in all environments except residential environments and environments that are directly connected to a low-voltage supply network that supplies residential buildings Note: Class A equipment is intended for use in an industrial environment. This equipment may cause radio disturbances in residential environments, due to possible conducted as well as radiated disturbances. In this case, the operator may be required to take appropriate measures to eliminate these disturbances.

 Class B equipment:

Equipment suitable for use in residential environments and environments that are directly connected to a low-voltage supply network that supplies residential buildings

Repair and service

1. The product may be opened only by authorized, specially trained personnel. Before any work is performed on the product or before the product is opened, it must be disconnected from the AC supply network. Otherwise, personnel will be exposed to the risk of an electric shock.

and analogously with EN 55022/CISPR 22,

1171.0000.42 - 07 Page 5

asic Safety Instructions

2. Adjustments, replacement of parts, maintenance and repair may be performed only by electrical experts authorized by Rohde & Schwarz. Only original parts may be used for replacing parts relevant to safety (e.g. power switches, power transformers, fuses). A safety test must always be performed after parts relevant to safety have been replaced (visual inspection, protective conductor test, insulation resistance measurement, leakage current measurement, functional test). This helps ensure the continued safety of the product.

Batteries and rechargeable batteries/cells

If the information regarding batteries and rechargeable batteries/cells is not observed either at all or to the extent necessary, product users may be exposed to the risk of explosions, fire and/or serious personal injury, and, in some cases, death. Batteries and rechargeable batteries with alkaline electrolytes (e.g. lithium cells) must be handled in accordance with the EN 62133 standard.

1. Cells must not be taken apart or crushed.

2. Cells or batteries must not be exposed to heat or fire. Storage in direct sunlight must be avoided. Keep cells and batteries clean and dry. Clean soiled connectors using a dry, clean cloth.

3. Cells or batteries must not be short-circuited. Cells or batteries must not be stored in a box or in a drawer where they can short-circuit each other, or where they can be short-circuited by other conductive materials. Cells and batteries must not be removed from their original packaging until they are ready to be used.

4. Cells and batteries must not be exposed to any mechanical shocks that are stronger than permitted.

5. If a cell develops a leak, the fluid must not be allowed to come into contact with the skin or eyes. If contact occurs, wash the affected area with plenty of water and seek medical aid.

6. Improperly replacing or charging cells or batteries that contain alkaline electrolytes (e.g. lithium cells) can cause explosions. Replace cells or batteries only with the matching Rohde & Schwarz type (see parts list) in order to ensure the safety of the product.

7. Cells and batteries must be recycled and kept separate from residual waste. Rechargeable batteries and normal batteries that contain lead, mercury or cadmium are hazardous waste. Observe the national regulations regarding waste disposal and recycling.

Transport

1. The product may be very heavy. Therefore, the product must be handled with care. In some cases, the user may require a suitable means of lifting or moving the product (e.g. with a lift-truck) to avoid back or other physical injuries.

2. Handles on the products are designed exclusively to enable personnel to transport the product. It is therefore not permissible to use handles to fasten the product to or on transport equipment such as cranes, fork lifts, wagons, etc. The user is responsible for securely fastening the products to or on the means of transport or lifting. Observe the safety regulations of the manufacturer of the means of transport or lifting. Noncompliance can result in personal injury or material damage.

3. If you use the product in a vehicle, it is the sole responsibility of the driver to drive the vehicle safely and properly. The manufacturer assumes no responsibility for accidents or collisions. Never use the product in a moving vehicle if doing so could distract the driver of the vehicle. Adequately secure the product in the vehicle to prevent injuries or other damage in the event of an accident.

1171.0000.42 - 07 Page 6

nstrucciones de seguridad elementales

Waste disposal/Environmental protection

1. Specially marked equipment has a battery or accumulator that must not be disposed of with unsorted municipal waste, but must be collected separately. It may only be disposed of at a suitable collection point or via a Rohde & Schwarz customer service center.

2. Waste electrical and electronic equipment must not be disposed of with unsorted municipal waste, but

ust be collected separately.

m Rohde & Schwarz GmbH & Co. KG has developed a disposal concept and takes full responsibility for take-back obligations and disposal obligations for manufacturers within the EU. Contact your Rohde & Schwarz customer service center for environmentally responsible disposal of the product.

3. If products or their components are mechanically and/or thermally processed in a manner that goes beyond their intended use, hazardous substances (heavy-metal dust such as lead, beryllium, nickel) may be released. For this reason, the product may only be disassembled by specially trained personnel. Improper disassembly may be hazardous to your health. National waste disposal regulations must be observed.

4. If handling the product releases hazardous substances or fuels that must be disposed of in a special way, e.g. coolants or engine oils that must be replenished regularly, the safety instructions of the manufacturer of the hazardous substances or fuels and the applicable regional waste disposal regulations must be observed. Also observe the relevant safety instructions in the product documentation. The improper disposal of hazardous substances or fuels can cause health problems and lead to environmental damage.

For additional information about environmental protection, visit the Rohde & Schwarz website.

Instrucciones de seguridad elementales

¡Es imprescindible leer y cumplir las siguientes instrucciones e informaciones de seguridad!

El principio del grupo de empresas Rohde & Schwarz consiste en tener nuestros productos siempre al día con los estándares de seguridad y de ofrecer a nuestros clientes el máximo grado de seguridad. Nuestros productos y todos los equipos adicionales son siempre fabricados y examinados según las normas de seguridad vigentes. Nuestro sistema de garantía de calidad controla constantemente que sean cumplidas estas normas. El presente producto ha sido fabricado y examinado según el certificado de conformidad de la UE y ha salido de nuestra planta en estado impecable según los estándares técnicos de seguridad. Para poder preservar este estado y garantizar un funcionamiento libre de peligros, el usuario deberá atenerse a todas las indicaciones, informaciones de seguridad y notas de alerta. El grupo de empresas Rohde & Schwarz está siempre a su disposición en caso de que tengan preguntas referentes a estas informaciones de seguridad.

Además queda en la responsabilidad del usuario utilizar el producto en la forma debida. Este producto está destinado exclusivamente al uso en la industria y el laboratorio o, si ha sido expresamente autorizado, para aplicaciones de campo y de ninguna manera deberá ser utilizado de modo que alguna persona/cosa pueda sufrir daño. El uso del producto fuera de sus fines definidos o sin tener en cuenta las instrucciones del fabricante queda en la responsabilidad del usuario. El fabricante no se hace en ninguna forma responsable de consecuencias a causa del mal uso del producto.

1171.0000.42 - 07 Page 7

nstrucciones de seguridad elementales

Se parte del uso correcto del producto para los fines definidos si el producto es utilizado conforme a las indicaciones de la correspondiente documentación del producto y dentro del margen de rendimiento definido (ver hoja de datos, documentación, informaciones de seguridad que siguen). El uso del producto hace necesarios conocimientos técnicos y ciertos conocimientos del idioma inglés. Por eso se debe tener en cuenta que el producto solo pueda ser operado por personal especializado o personas instruidas en profundidad con las capacidades correspondientes. Si fuera necesaria indumentaria de seguridad para el

so de productos de Rohde & Schwarz, encontraría la información debida en la documentación del

u producto en el capítulo correspondiente. Guarde bien las informaciones de seguridad elementales, así como la documentación del producto, y entréguelas a usuarios posteriores.

Tener en cuenta las informaciones de seguridad sirve para evitar en lo posible lesiones o daños por peligros de toda clase. Por eso es imprescindible leer detalladamente y comprender por completo las siguientes informaciones de seguridad antes de usar el producto, y respetarlas durante el uso del producto. Deberán tenerse en cuenta todas las demás informaciones de seguridad, como p. ej. las referentes a la protección de personas, que encontrarán en el capítulo correspondiente de la documentación del producto y que también son de obligado cumplimiento. En las presentes informaciones de seguridad se recogen todos los objetos que distribuye el grupo de empresas Rohde & Schwarz bajo la denominación de "producto", entre ellos también aparatos, instalaciones así como toda clase de accesorios. Los datos específicos del producto figuran en la hoja de datos y en la documentación del producto.

Señalización de seguridad de los productos

Las siguientes señales de seguridad se utilizan en los productos para advertir sobre riesgos y peligros.

Símbolo Significado Símbolo Significado

Aviso: punto de peligro general

Observar la documentación del producto

Atención en el manejo de dispositivos de peso elevado

Peligro de choque eléctrico Corriente continua (DC)

Advertencia: superficie caliente Corriente alterna (AC)

Conexión a conductor de protección Corriente continua / Corriente alterna (DC/AC)

Conexión a tierra El aparato está protegido en su totalidad por un

Tensión de alimentación de PUESTA EN MARCHA / PARADA

Indicación de estado de espera (standby)

aislamiento doble (reforzado)

Conexión a masa Distintivo de la UE para baterías y

acumuladores

Más información en la sección "Eliminación/protección del medio ambiente", punto 1.

1171.0000.42 - 07 Page 8

nstrucciones de seguridad elementales

Símbolo Significado Símbolo Significado

Aviso: Cuidado en el manejo de dispositivos sensibles a la electrostática (ESD)

Advertencia: rayo láser

Más información en la sección "Funcionamiento", punto 7.

Distintivo de la UE para la eliminación por separado de dispositivos eléctricos y electrónicos

Más información en la sección "Eliminación/protección del medio ambiente", punto 2.

Palabras de señal y su significado

En la documentación del producto se utilizan las siguientes palabras de señal con el fin de advertir contra riesgos y peligros.

Indica una situación de peligro que, si no se evita, causa lesiones graves o incluso la muerte.

Indica una situación de peligro que, si no se evita, puede causar lesiones graves o incluso la muerte.

Indica una situación de peligro que, si no se evita, puede causar lesiones leves o moderadas.

Indica información que se considera importante, pero no en relación con situaciones de peligro; p. ej., avisos sobre posibles daños materiales. En la documentación del producto se emplea de forma sinónima el término CUIDADO.

Las palabras de señal corresponden a la definición habitual para aplicaciones civiles en el área económica europea. Pueden existir definiciones diferentes a esta definición en otras áreas económicas o en aplicaciones militares. Por eso se deberá tener en cuenta que las palabras de señal aquí descritas sean utilizadas siempre solamente en combinación con la correspondiente documentación del producto y solamente en combinación con el producto correspondiente. La utilización de las palabras de señal en combinación con productos o documentaciones que no les correspondan puede llevar a interpretaciones equivocadas y tener por consecuencia daños en personas u objetos.

Estados operativos y posiciones de funcionamiento

El producto solamente debe ser utilizado según lo indicado por el fabricante respecto a los estados operativos y posiciones de funcionamiento sin que se obstruya la ventilación. Si no se siguen las indicaciones del fabricante, pueden producirse choques eléctricos, incendios y/o lesiones graves con posible consecuencia de muerte. En todos los trabajos deberán ser tenidas en cuenta las normas nacionales y locales de seguridad del trabajo y de prevención de accidentes.

1171.0000.42 - 07 Page 9

nstrucciones de seguridad elementales

1. Si no se convino de otra manera, es para los productos Rohde & Schwarz válido lo que sigue: como posición de funcionamiento se define por principio la posición con el suelo de la caja para abajo, modo de protección IP 2X, uso solamente en estancias interiores, utilización hasta 2000 m sobre el nivel del mar, transporte hasta 4500 m sobre el nivel del mar. Se aplicará una tolerancia de ±10 % sobre el voltaje nominal y de ±5 % sobre la frecuencia nominal. Categoría de sobrecarga eléctrica 2, índice de suciedad 2.

2. No sitúe el producto encima de superficies, vehículos, estantes o mesas, que por sus características de peso o de estabilidad no sean aptos para él. Siga siempre las instrucciones de instalación del fabricante cuando instale y asegure el producto en objetos o estructuras (p. ej. paredes y estantes). Si se realiza la instalación de modo distinto al indicado en la documentación del producto, se pueden causar lesiones o, en determinadas circunstancias, incluso la muerte.

3. No ponga el producto sobre aparatos que generen calor (p. ej. radiadores o calefactores). La temperatura ambiente no debe superar la temperatura máxima especificada en la documentación del producto o en la hoja de datos. En caso de sobrecalentamiento del producto, pueden producirse choques eléctricos, incendios y/o lesiones graves con posible consecuencia de muerte.

Seguridad eléctrica

Si no se siguen (o se siguen de modo insuficiente) las indicaciones del fabricante en cuanto a seguridad eléctrica, pueden producirse choques eléctricos, incendios y/o lesiones graves con posible consecuencia de muerte.

1. Antes de la puesta en marcha del producto se deberá comprobar siempre que la tensión preseleccionada en el producto coincida con la de la red de alimentación eléctrica. Si es necesario modificar el ajuste de tensión, también se deberán cambiar en caso dado los fusibles correspondientes del producto.

2. Los productos de la clase de protección I con alimentación móvil y enchufe individual solamente podrán enchufarse a tomas de corriente con contacto de seguridad y con conductor de protección conectado.

3. Queda prohibida la interrupción intencionada del conductor de protección, tanto en la toma de corriente como en el mismo producto. La interrupción puede tener como consecuencia el riesgo de que el producto sea fuente de choques eléctricos. Si se utilizan cables alargadores o regletas de enchufe, deberá garantizarse la realización de un examen regular de los mismos en cuanto a su estado técnico de seguridad.

4. Si el producto no está equipado con un interruptor para desconectarlo de la red, o bien si el interruptor existente no resulta apropiado para la desconexión de la red, el enchufe del cable de conexión se deberá considerar como un dispositivo de desconexión. El dispositivo de desconexión se debe poder alcanzar fácilmente y debe estar siempre bien accesible. Si, p. ej., el enchufe de conexión a la red es el dispositivo de desconexión, la longitud del cable de conexión no debe superar 3 m). Los interruptores selectores o electrónicos no son aptos para el corte de la red eléctrica. Si se integran productos sin interruptor en bastidores o instalaciones, se deberá colocar el interruptor en el nivel de la instalación.

5. No utilice nunca el producto si está dañado el cable de conexión a red. Compruebe regularmente el correcto estado de los cables de conexión a red. Asegúrese, mediante las medidas de protección y de instalación adecuadas, de que el cable de conexión a red no pueda ser dañado o de que nadie pueda ser dañado por él, p. ej. al tropezar o por un choque eléctrico.

1171.0000.42 - 07 Page 10

nstrucciones de seguridad elementales

6. Solamente está permitido el funcionamiento en redes de alimentación TN/TT aseguradas con fusibles de 16 A como máximo (utilización de fusibles de mayor amperaje solo previa consulta con el grupo de empresas Rohde & Schwarz).

7. Nunca conecte el enchufe en tomas de corriente sucias o llenas de polvo. Introduzca el enchufe por completo y fuertemente en la toma de corriente. La no observación de estas medidas puede provocar chispas, fuego y/o lesiones.

8. No sobrecargue las tomas de corriente, los cables alargadores o las regletas de enchufe ya que esto podría causar fuego o choques eléctricos.

9. En las mediciones en circuitos de corriente con una tensión U

> 30 V se deberán tomar las medidas

eff

apropiadas para impedir cualquier peligro (p. ej. medios de medición adecuados, seguros, limitación de tensión, corte protector, aislamiento etc.).

10. Para la conexión con dispositivos informáticos como un PC o un ordenador industrial, debe comprobarse que éstos cumplan los estándares IEC60950-1/EN60950-1 o IEC61010-1/EN 61010-1 válidos en cada caso.

11. A menos que esté permitido expresamente, no retire nunca la tapa ni componentes de la carcasa mientras el producto esté en servicio. Esto pone a descubierto los cables y componentes eléctricos y puede causar lesiones, fuego o daños en el producto.

12. Si un producto se instala en un lugar fijo, se deberá primero conectar el conductor de protección fijo con el conductor de protección del producto antes de hacer cualquier otra conexión. La instalación y la conexión deberán ser efectuadas por un electricista especializado.

13. En el caso de dispositivos fijos que no estén provistos de fusibles, interruptor automático ni otros mecanismos de seguridad similares, el circuito de alimentación debe estar protegido de modo que todas las personas que puedan acceder al producto, así como el producto mismo, estén a salvo de posibles daños.

14. Todo producto debe estar protegido contra sobretensión (debida p. ej. a una caída del rayo) mediante los correspondientes sistemas de protección. Si no, el personal que lo utilice quedará expuesto al peligro de choque eléctrico.

15. No debe introducirse en los orificios de la caja del aparato ningún objeto que no esté destinado a ello. Esto puede producir cortocircuitos en el producto y/o puede causar choques eléctricos, fuego o lesiones.

16. Salvo indicación contraria, los productos no están impermeabilizados (ver también el capítulo "Estados operativos y posiciones de funcionamiento", punto 1). Por eso es necesario tomar las medidas necesarias para evitar la entrada de líquidos. En caso contrario, existe peligro de choque eléctrico para el usuario o de daños en el producto, que también pueden redundar en peligro para las personas.

17. No utilice el producto en condiciones en las que pueda producirse o ya se hayan producido condensaciones sobre el producto o en el interior de éste, como p. ej. al desplazarlo de un lugar frío a otro caliente. La entrada de agua aumenta el riesgo de choque eléctrico.

18. Antes de la limpieza, desconecte por completo el producto de la alimentación de tensión (p. ej. red de alimentación o batería). Realice la limpieza de los aparatos con un paño suave, que no se deshilache. No utilice bajo ningún concepto productos de limpieza químicos como alcohol, acetona o diluyentes para lacas nitrocelulósicas.

1171.0000.42 - 07 Page 11

nstrucciones de seguridad elementales

Funcionamiento

1. El uso del producto requiere instrucciones especiales y una alta concentración durante el manejo. Debe asegurarse que las personas que manejen el producto estén a la altura de los requerimientos necesarios en cuanto a aptitudes físicas, psíquicas y emocionales, ya que de otra manera no se pueden excluir lesiones o daños de objetos. El empresario u operador es responsable de seleccionar el personal usuario apto para el manejo del producto.

2. Antes de desplazar o transportar el producto, lea y tenga en cuenta el capítulo "Transporte".

3. Como con todo producto de fabricación industrial no puede quedar excluida en general la posibilidad de que se produzcan alergias provocadas por algunos materiales empleados Slos llamados alérgenos (p. ej. el níquel)S. Si durante el manejo de productos Rohde & Schwarz se producen reacciones alérgicas, como p. ej. irritaciones cutáneas, estornudos continuos, enrojecimiento de la conjuntiva o dificultades respiratorias, debe avisarse inmediatamente a un médico para investigar las causas y evitar cualquier molestia o daño a la salud.

4. Antes de la manipulación mecánica y/o térmica o el desmontaje del producto, debe tenerse en cuenta imprescindiblemente el capítulo "Eliminación/protección del medio ambiente", punto 1.

5. Ciertos productos, como p. ej. las instalaciones de radiocomunicación RF, pueden a causa de su función natural, emitir una radiación electromagnética aumentada. Deben tomarse todas las medidas necesarias para la protección de las mujeres embarazadas. También las personas con marcapasos pueden correr peligro a causa de la radiación electromagnética. El empresario/operador tiene la obligación de evaluar y señalizar las áreas de trabajo en las que exista un riesgo elevado de exposición a radiaciones.

6. Tenga en cuenta que en caso de incendio pueden desprenderse del producto sustancias tóxicas (gases, líquidos etc.) que pueden generar daños a la salud. Por eso, en caso de incendio deben usarse medidas adecuadas, como p. ej. máscaras antigás e indumentaria de protección.

7. Los productos con láser están provistos de indicaciones de advertencia normalizadas en función de la clase de láser del que se trate. Los rayos láser pueden provocar daños de tipo biológico a causa de las propiedades de su radiación y debido a su concentración extrema de potencia electromagnética. En caso de que un producto Rohde & Schwarz contenga un producto láser (p. ej. un lector de CD/DVD), no debe usarse ninguna otra configuración o función aparte de las descritas en la documentación del producto, a fin de evitar lesiones (p. ej. debidas a irradiación láser).

8. Clases de compatibilidad electromagnética (conforme a EN 55011 / CISPR 11; y en analogía con EN 55022 / CISPR 22, EN 55032 / CISPR 32)  Aparato de clase A:

Aparato adecuado para su uso en todos los entornos excepto en los residenciales y en aquellos conectados directamente a una red de distribución de baja tensión que suministra corriente a edificios residenciales. Nota: Los aparatos de clase A están destinados al uso en entornos industriales. Estos aparatos pueden causar perturbaciones radioeléctricas en entornos residenciales debido a posibles perturbaciones guiadas o radiadas. En este caso, se le podrá solicitar al operador que tome las medidas adecuadas para eliminar estas perturbaciones.

 Aparato de clase B:

Aparato adecuado para su uso en entornos residenciales, así como en aquellos conectados directamente a una red de distribución de baja tensión que suministra corriente a edificios residenciales.

1171.0000.42 - 07 Page 12

nstrucciones de seguridad elementales

Reparación y mantenimiento

1. El producto solamente debe ser abierto por personal especializado con autorización para ello. Antes de manipular el producto o abrirlo, es obligatorio desconectarlo de la tensión de alimentación, para evitar toda posibilidad de choque eléctrico.

2. El ajuste, el cambio de partes, el mantenimiento y la reparación deberán ser efectuadas solamente

or electricistas autorizados por Rohde & Schwarz. Si se reponen partes con importancia para los

p aspectos de seguridad (p. ej. el enchufe, los transformadores o los fusibles), solamente podrán ser sustituidos por partes originales. Después de cada cambio de partes relevantes para la seguridad deberá realizarse un control de seguridad (control a primera vista, control del conductor de protección, medición de resistencia de aislamiento, medición de la corriente de fuga, control de funcionamiento). Con esto queda garantizada la seguridad del producto.

Baterías y acumuladores o celdas

Si no se siguen (o se siguen de modo insuficiente) las indicaciones en cuanto a las baterías y acumuladores o celdas, pueden producirse explosiones, incendios y/o lesiones graves con posible consecuencia de muerte. El manejo de baterías y acumuladores con electrolitos alcalinos (p. ej. celdas de litio) debe seguir el estándar EN 62133.

1. No deben desmontarse, abrirse ni triturarse las celdas.

2. Las celdas o baterías no deben someterse a calor ni fuego. Debe evitarse el almacenamiento a la luz directa del sol. Las celdas y baterías deben mantenerse limpias y secas. Limpiar las conexiones sucias con un paño seco y limpio.

3. Las celdas o baterías no deben cortocircuitarse. Es peligroso almacenar las celdas o baterías en estuches o cajones en cuyo interior puedan cortocircuitarse por contacto recíproco o por contacto con otros materiales conductores. No deben extraerse las celdas o baterías de sus embalajes originales hasta el momento en que vayan a utilizarse.

4. Las celdas o baterías no deben someterse a impactos mecánicos fuertes indebidos.

5. En caso de falta de estanqueidad de una celda, el líquido vertido no debe entrar en contacto con la piel ni los ojos. Si se produce contacto, lavar con agua abundante la zona afectada y avisar a un médico.

6. En caso de cambio o recarga inadecuados, las celdas o baterías que contienen electrolitos alcalinos (p. ej. las celdas de litio) pueden explotar. Para garantizar la seguridad del producto, las celdas o baterías solo deben ser sustituidas por el tipo Rohde & Schwarz correspondiente (ver lista de recambios).

7. Las baterías y celdas deben reciclarse y no deben tirarse a la basura doméstica. Las baterías o acumuladores que contienen plomo, mercurio o cadmio deben tratarse como residuos especiales. Respete en esta relación las normas nacionales de eliminación y reciclaje.

Transporte

1. El producto puede tener un peso elevado. Por eso es necesario desplazarlo o transportarlo con precaución y, si es necesario, usando un sistema de elevación adecuado (p. ej. una carretilla elevadora), a fin de evitar lesiones en la espalda u otros daños personales.

1171.0000.42 - 07 Page 13

nstrucciones de seguridad elementales

2. Las asas instaladas en los productos sirven solamente de ayuda para el transporte del producto por personas. Por eso no está permitido utilizar las asas para la sujeción en o sobre medios de transporte como p. ej. grúas, carretillas elevadoras de horquilla, carros etc. Es responsabilidad suya fijar los productos de manera segura a los medios de transporte o elevación. Para evitar daños personales o daños en el producto, siga las instrucciones de seguridad del fabricante del medio de transporte o elevación utilizado.

3. Si se utiliza el producto dentro de un vehículo, recae de manera exclusiva en el conductor la responsabilidad de conducir el vehículo de manera segura y adecuada. El fabricante no asumirá ninguna responsabilidad por accidentes o colisiones. No utilice nunca el producto dentro de un vehículo en movimiento si esto pudiera distraer al conductor. Asegure el producto dentro del vehículo debidamente para evitar, en caso de un accidente, lesiones u otra clase de daños.

Eliminación/protección del medio ambiente

1. Los dispositivos marcados contienen una batería o un acumulador que no se debe desechar con los residuos domésticos sin clasificar, sino que debe ser recogido por separado. La eliminación se debe efectuar exclusivamente a través de un punto de recogida apropiado o del servicio de atención al cliente de Rohde & Schwarz.

2. Los dispositivos eléctricos usados no se deben desechar con los residuos domésticos sin clasificar, sino que deben ser recogidos por separado. Rohde & Schwarz GmbH & Co.KG ha elaborado un concepto de eliminación de residuos y asume plenamente los deberes de recogida y eliminación para los fabricantes dentro de la UE. Para desechar el producto de manera respetuosa con el medio ambiente, diríjase a su servicio de atención al cliente de Rohde & Schwarz.

3. Si se trabaja de manera mecánica y/o térmica cualquier producto o componente más allá del funcionamiento previsto, pueden liberarse sustancias peligrosas (polvos con contenido de metales pesados como p. ej. plomo, berilio o níquel). Por eso el producto solo debe ser desmontado por personal especializado con formación adecuada. Un desmontaje inadecuado puede ocasionar daños para la salud. Se deben tener en cuenta las directivas nacionales referentes a la eliminación de residuos.

4. En caso de que durante el trato del producto se formen sustancias peligrosas o combustibles que deban tratarse como residuos especiales (p. ej. refrigerantes o aceites de motor con intervalos de cambio definidos), deben tenerse en cuenta las indicaciones de seguridad del fabricante de dichas sustancias y las normas regionales de eliminación de residuos. Tenga en cuenta también en caso necesario las indicaciones de seguridad especiales contenidas en la documentación del producto. La eliminación incorrecta de sustancias peligrosas o combustibles puede causar daños a la salud o daños al medio ambiente.

Se puede encontrar más información sobre la protección del medio ambiente en la página web de Rohde & Schwarz.

1171.0000.42 - 07 Page 14

Quality management

Certied Quality System

ISO 9001

and environmental management

Sehr geehrter Kunde,

Sie haben sich für den Kauf eines Rohde & Schwarz Produktes entschieden. Sie erhalten damit ein nach modernsten Fertigungsmethoden hergestelltes Produkt. Es wurde nach den Regeln unserer Qualitäts- und Umweltmanagementsysteme entwickelt, gefertigt und geprüft. Rohde & Schwarz ist unter anderem nach den Managementsystemen ISO 9001 und ISO 14001 zertifiziert.

Der Umwelt verpflichtet

❙ Energie-efziente,

RoHS-konforme Produkte

❙ Kontinuierliche

Weiterentwicklung nachhaltiger Umweltkonzepte

❙ ISO 14001-zertiziertes

Umweltmanagementsystem

Dear customer,

You have decided to buy a Rohde & Schwarz product. This product has been manufactured using the most advanced methods. It was developed, manufactured and tested in compliance with our quality management and environmental management systems. Rohde & Schwarz has been certified, for example, according to the ISO 9001 and ISO 14001 management systems.

Environmental commitment

❙ Energy-efcient products ❙ Continuous improvement in

environmental sustainability

❙ ISO 14001-certied

environmental management system

Certied Environmental System

ISO 14001

Cher client,

Vous avez choisi d’acheter un produit Rohde & Schwarz. Vous disposez donc d’un produit fabriqué d’après les méthodes les plus avancées. Le développement, la fabrication et les tests de ce produit ont été effectués selon nos systèmes de management de qualité et de management environnemental. La société Rohde & Schwarz a été homologuée, entre autres, conformément aux systèmes de management ISO 9001 et ISO 14001.

Engagement écologique

❙ Produits à efcience

énergétique

❙ Amélioration continue de la

durabilité environnementale

❙ Système de management

environnemental certié selon

ISO 14001

1171.0200.11 V 05.01

1171020011

Customer Support

Technical support – where and when you need it

For quick, expert help with any Rohde & Schwarz equipment, contact one of our Customer Support Centers. A team of highly qualified engineers provides telephone support and will work with you to find a solution to your query on any aspect of the operation, programming or applications of Rohde & Schwarz equipment.

Up-to-date information and upgrades

To keep your instrument up-to-date and to be informed about new application notes related to your instrument, please send an e-mail to the Customer Support Center stating your instrument and your wish. We will take care that you will get the right information.

Europe, Africa, Middle East

North America

Latin America

Asia/Pacific

China

Phone +49 89 4129 12345

customersupport@rohde-schwarz.com

Phone 1-888-TEST-RSA (1-888-837-8772)

customer.support@rsa.rohde-schwarz.com

Phone +1-410-910-7988

customersupport.la@rohde-schwarz.com

Phone +65 65 13 04 88

customersupport.asia@rohde-schwarz.com

Phone +86-800-810-8228 / +86-400-650-5896

customersupport.china@rohde-schwarz.com

1171.0200.22-06.00

R&S FSU Documentation Overview

Documentation Overview

The documentation of the R&S FSU consists of base unit manuals and option manuals. All manuals are provided in PDF format on the CD-ROM delivered with the instrument. Each software option available for the instrument is described in a separate software manual.

The base unit documentation comprises the following manuals and documents:

• Quick Start Guide

• Operating Manual

• Service Manual

• Internet Site

• Release Notes

Apart from the base unit, these manuals describe the following models and options of the R&S FSU Spectrum Analyzer. Options that are not listed are described in separate manuals. These manuals are provided on an extra CD-ROM. For an overview of all options available for the R&S FSU visit the R&S FSU Spectrum Analyzer Internet site.

Base unit models:

• R&S FSU3 (20 Hz to 3.6 GHz)

• R&S FSU8 (20 Hz to 8 GHz)

• R&S FSU26 (20 Hz to 26.5 GHz)

• R&S FSU31 (20 Hz to 31 GHz)

• R&S FSU32 (20 Hz to 32 GHz)

• R&S FSU43 (20 Hz to 43 GHz)

• R&S FSU46 (20 Hz to 40 GHz)

• R&S FSU50 (20 Hz to 50 GHz)

• R&S FSU67 (20 Hz to 67 GHz)

Options described in the base unit manuals:

• R&S FSU-B9 (Tracking Generator)

• R&S FSP-B10 (External Generator Control)

• R&S FSP-B16 (LAN Interface)

• R&S FSU-B21 (External Mixer)

• R&S FSU-B27 (Broadband FM Demodulator)

• R&S FSP-B28 (Trigger Port)

Operating Manual 1313.9646.12 - 02 1.3

R&S FSU Documentation Overview

Quick Start Guide

This manual is delivered with the instrument in printed form and in PDF format on the CD-ROM. It provides the information needed to set up and start working with the instrument. Basic operations and basic measurements are described. Also a brief introduction to remote control is given. More detailed descriptions are provided in the Operating Manual. The Quick Start Guide includes general information (e.g. Safety Instructions) and the following chapters:

Chapter 1 Front and Rear Panel

Chapter 2 Preparing for Use

Chapter 3 Firmware-Update and Installation of Firmware Options

Chapter 4 Basic Operation

Chapter 5 Basic Measurement Examples

Chapter 6 Brief Introduction to Remote Control

Appendix

Operating Manual

This manual is a supplement to the Quick Start Guide and is available in PDF format on the CD-ROM delivered with the instrument. To retain the familiar structure that applies to all operating manuals of Rohde&Schwarz Test & Measurement instruments, the chapters 1 and 3 exist, but only in form of references to the corresponding Quick Start Guide chapters. The operating manual has the following chapters:

Chapter 1 Putting into Operation

see Quick Start Guide chapters 1 and 2.

Chapter 2 Getting Started

see Quick Start Guide chapter 5.

Chapter 3 Manual Operation

see Quick Start Guide chapter 4.

Chapter 4 Instrument Functions

forms a reference for manual operation of the R&S FSU and contains a description of all instrument functions and their application.

Chapter 5 Remote Control - Basics

describes the basics for programming the R&S FSU, command processing and the status reporting system.

Chapter 6 Remote Control - Description of Commands

lists all the remote-control commands defined for the instrument.

Chapter 7 Remote Control - Programming Examples

contains program examples for a number of typical applications of the R&S FSU.

Chapter 8 Maintenance and Instrument Interfaces

describes preventive maintenance and the characteristics of the instrument’s interfaces.

Chapter 9 Error Messages

gives a list of error messages that the R&S FSU may generate.

Index contains an index for the chapters 1 to 9 of the operating manual.

1.4 Operating Manual 1313.9646.12 - 02

R&S FSU Documentation Overview

Service Manual

This manual is available in PDF format on the CD-ROM delivered with the instrument. It informs on how to check compliance with rated specifications, on instrument function, repair, troubleshooting and fault elimination. It contains all information required for repairing the R&S FSU by the replacement of modules. The manual includes the following chapters:

Chapter 1 Performance Test

Chapter 2 Adjustment

Chapter 3 Repair

Chapter 4 Software Update / Installing Options

Chapter 5 Documents

Internet Site

The Internet site at: http://www.rohde-schwarz.com/product/fsu.html provides the most up to date information on the R&S FSU.

The current operating manual at a time is available as printable PDF file in the download area. Also provided for download are firmware updates including the associated release notes, instrument drivers, current data sheets and application notes.

Release Notes

The release notes describe the installation of the firmware, new and modified functions, eliminated problems, and last minute changes to the documentation. The corresponding firmware version is indicated on the title page of the release notes. The current release notes are provided in the Internet.

Operating Manual 1313.9646.12 - 02 1.5

R&S FSU Putting into Operation

1 Putting into Operation

For details refer to the Quick Start Guide chapter 1, “Front and Rear Panel” and chapter 2, “ Preparing for Use”.

1.1 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

2 Getting Started

2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2

2.2 Measuring the Spectra of Complex Signals . . . . . . . . . . . . . . . . . . . . . . . . 2.3

2.2.1 Intermodulation Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3

2.2.1.1 Measurement Example – Measuring the R&S FSU’s intrinsic

intermodulation distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5

2.3 Measuring Signals in the Vicinity of Noise . . . . . . . . . . . . . . . . . . . . . . . . . 2.9

2.3.1 Measurement example – Measuring the level of the internal

reference generator at low S/N ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.13

2.4 Noise Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16

2.4.1 Measuring noise power density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16

2.4.1.1 Measurement example – Measuring the intrinsic noise power density of the R&S FSU at 1 GHz and calculating the R&S FSU’s

noise figure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.16

2.4.2 Measurement of Noise Power within a Transmission Channel . . . . . . . 2.19

2.4.2.1 Measurement Example – Measuring the intrinsic noise of the R&S FSU at 1 GHz in a 1.23 MHz channel bandwidth with the

channel power function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.19

2.4.3 Measuring Phase Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.24

2.4.3.1 Measurement Example – Measuring the phase noise of a

signal generator at a carrier offset of 10 kHz . . . . . . . . . . . . . . . . . . . . . . 2.24

2.5 Measurements on Modulated Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.26

2.5.1 Measurements on AM signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.26

2.5.1.1 Measurement Example 1 – Displaying the AF of an AM signal in

the time domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.26

2.5.1.2 Measurement Example 2 – Measuring the modulation depth

of an AM carrier in the frequency domain . . . . . . . . . . . . . . . . . . . . . . . . . 2.27

2.5.2 Measurements on FM Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.29

2.5.2.1 Measurement Example – Displaying the AF of an FM carrier . . . . 2.29

2.5.3 Measuring Channel Power and Adjacent Channel Power . . . . . . . . . . 2.31

2.5.3.1 Measurement Example 1 – ACPR measurement on an IS95

CDMA Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.32

2.5.3.2 Measurement Example 2 – Measuring the adjacent channel

power of an IS136 TDMA signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.36

2.5.3.3 Measurement Example 3 – Measuring the Modulation Spectrum

in Burst Mode with the Gated Sweep Function . . . . . . . . . . . . . . . . . . . . . 2.39

2.5.3.4 Measurement Example 4 – Measuring the Transient Spectrum

in Burst Mode with the Fast ACP function . . . . . . . . . . . . . . . . . . . . . . . . . 2.41

2.5.3.5 Measurement Example 5 – Measuring adjacent channel

power of a W-CDMA uplink signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.43

2.5.4 Amplitude Distribution Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . 2.46

2.5.4.1 Measurement Example – Measuring the APD and CCDF of

white noise generated by the R&S FSU . . . . . . . . . . . . . . . . . . . . . . . . . . 2.46

Operating Manual 1313.9646.12 - 02 2.1

R&S FSU Getting Started

Introduction

2.1 Introduction

This chapter explains how to operate the R&S FSU using typical measurements as examples.

The basic operating steps such as selecting the menus and setting parameters are described in the Quick Start Guide, chapter 4, "Basic Operation". Furthermore, the screen structure and displayed function indicators are explained in this chapter.

Chapter “Instrument Functions” describes all the menus and R&S FSU functions.

All of the following examples are based on the standard settings of the R&S FSU. These are set with the PRESET key. A complete listing of the standard settings can be found in chapter “Instrument Functions”, section “R&S FSU Initial Configuration –

PRESET Key” on page 4.5. Examples of more basic character are provided in the

Quick Start Guide, chapter 5, as an introduction.

2.2 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measuring the Spectra of Complex Signals

2.2 Measuring the Spectra of Complex Signals

2.2.1 Intermodulation Measurements

If several signals are applied to a DUT with non-linear characteristics, unwanted mixing products are generated – mostly by active components such as amplifiers or mixers. The products created by 3 some as they have frequencies close to the useful signals and, compared with other products, are closest in level to the useful signals. The fundamental wave of one signal is mixed with the 2

= 2 × fu1 – fu2 (6)

= 2 × fu2 – fu1 (7)

harmonic of the other signal.

order intermodulation are particularly trouble-

where f

and fs2 are the frequencies of the intermodulation products and fu1 and f

the frequencies of the useful signals.

The following diagram shows the position of the intermodulation products in the frequency domain.

Level

∆

Fig. 2.1 3rd order intermodulation products

∆

Frequency

Example:

fu1 = 100 MHz, fu2 = 100.03 MHz

= 2 × fu1 – fu2 = 2 × 100 MHz – 100.03 MHz = 99.97 MHz

= 2 × fu2 – fu1 = 2 × 100.03 MHz – 100 MHz = 100.06 MHz

The level of the intermodulation products depends on the level of the useful signals. If the level of the two useful signals is increased by 1 dB, the level of the intermodulation products is increased by 3 dB. The intermodulation distance d

is, therefore,

reduced by 2 dB. Fig. 2.2 shows how the levels of the useful signals and the 3 order intermodulation products are related.

Operating Manual 1313.9646.12 - 02 2.3

R&S FSU Getting Started

Measuring the Spectra of Complex Signals

Output

level

Intercept

point

Compression

Carrier

level

Fig. 2.2 Level of the 3rd order intermodulation products as a function of the level of the useful

signals

Intermodulation

products

Input level

The behavior of the signals can explained using an amplifier as an example. The change in the level of the useful signals at the output of the amplifier is proportional to the level change at the input of the amplifier as long as the amplifier is operating in linear range. If the level at the amplifier input is changed by 1 dB, there is a 1 dB level change at the amplifier output. At a certain input level, the amplifier enters saturation. The level at the amplifier output does not increase with increasing input level.

The level of the 3 level of the useful signals. The 3

order intermodulation products increases 3 times faster than the

order intercept is the virtual level at which the level of the useful signals and the level of the spurious products are identical, i.e. the intersection of the two straight lines. This level cannot be measured directly as the amplifier goes into saturation or is damaged before this level is reached.

The 3 intermodulation distance d

order intercept can be calculated from the known slopes of the lines, the

and the level of the useful signals.

TOI = a

with TOI (Third Order Intercept) being the 3

/ 2 + Pn (8)

order intercept in dBm and Pn the level

of a carrier in dBm.

With an intermodulation distance of 60 dB and an input level, P following 3

order intercept is obtained:

, of –20 dBm, the

TOI = 60 dBm / 2 + (-20 dBm) = 10 dBm.

2.4 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measuring the Spectra of Complex Signals

2.2.1.1 Measurement Example – Measuring the R&S FSU’s intrinsic intermodulation distance

To measure the intrinsic intermodulation distance, use the following test setup.

Test setup:

Signal generator settings (e.g. R&S SMIQ):

Level Frequency

Signal generator 1 -10 dBm 999.9 MHz

Signal generator 2 -10 dBm 1000.1 MHz

Measurement using the R&S FSU:

1. Set the R&S FSU to its default settings.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set center frequency to 1 GHz and the frequency span to 1 MHz.

➢ Press the FREQ key and enter 1 GHz. ➢ Press the SPAN key and enter 1 MHz.

3. Set the reference level to –10 dBm and RF attenuation to 0 dB.

➢ Press the AMPT key and enter -10 dBm. ➢ Press the RF ATTEN MANUAL softkey and enter 0 dB.

By reducing the RF attenuation to 0 dB, the level to the R&S FSU input mixer is increased. Therefore, 3

order intermodulation products are displayed.

4. Set the resolution bandwidth to 5 kHz.

➢ Press the BW key. ➢ Press the RES BW MANUAL softkey and enter 5 kHz.

By reducing the bandwidth, the noise is further reduced and the intermodulation products can be clearly seen.

5. Measuring intermodulation by means of the 3

order intercept

measurement function

➢ Press the MEAS key.

Operating Manual 1313.9646.12 - 02 2.5

R&S FSU Getting Started

Measuring the Spectra of Complex Signals

➢ Press the TOI softkey.

The R&S FSU activates four markers for measuring the intermodulation distance. Two markers are positioned on the useful signals and two on the intermodulation products. The 3

order intercept is calculated from the level difference between the useful signals and the intermodulation products. It is then displayed on the screen:

Fig. 2.3 Result of intrinsic intermodulation measurement on the R&S FSU. The 3rd order

intercept (TOI) is displayed at the top right corner of the grid

The level of a Spectrum Analyzer’s intrinsic intermodulation products depends on the RF level of the useful signals at the input mixer. When the RF attenuation is added, the mixer level is reduced and the intermodulation distance is increased. With an additional RF attenuation of 10 dB, the levels of the intermodulation products are reduced by 20 dB. The noise level is, however, increased by 10 dB.

6. Increasing RF attenuation to 10 dB to reduce intermodulation products.

➢ Press the AMPT key. ➢ Press the RF ATTEN MANUAL softkey and enter 10 dB.

The R&S FSU’s intrinsic intermodulation products disappear below the noise floor.

Fig. 2.4 If the RF attenuation is increased, the R&S FSU’s intrinsic intermodulation prod-

ucts disappear below the noise floor.

2.6 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measuring the Spectra of Complex Signals

Calculation method:

The method used by the R&S FSU to calculate the intercept point takes the average useful signal level P

in dBm and calculates the intermodulation d3 in dB as a func-

tion of the average value of the levels of the two intermodulation products. The third order intercept (TOI) is then calculated as follows:

TOI/dBm = ½ d

+ Pu

Intermodulation- free dynamic range

The Intermodulation – free dynamic range, i.e. the level range in which no internal intermodulation products are generated if two-tone signals are measured, is determined by the 3

order intercept point, the phase noise and the thermal noise of the R&S FSU. At high signal levels, the range is determined by intermodulation products. At low signal levels, intermodulation products disappear below the noise floor, i.e. the noise floor and the phase noise of the R&S FSU determine the range. The noise floor and the phase noise depend on the resolution bandwidth that has been selected. At the smallest resolution bandwidth, the noise floor and phase noise are at a minimum and so the maximum range is obtained. However, a large increase in sweep time is required for small resolution bandwidths. It is, therefore, best to select the largest resolution bandwidth possible to obtain the range that is required. Since phase noise decreases as the carrier-offset increases, its influence decreases with increasing frequency offset from the useful signals.

The following diagrams illustrate the intermodulation-free dynamic range as a function of the selected bandwidth and of the level at the input mixer (= signal level – set RF attenuation) at different useful signal offsets.

Distortion free dynamic range

1MHz carrier offset

-60

-70

-80

-90

-100

Dynamic range dB

-110

RBW=10 kHz

RBW=1 kHz

RBW=100 Hz

RBW=10 Hz

T.O.I

Thermal noise

-120

-60 -50 -40 -30 -20 -10

Mixer level

Fig. 2.5 Intermodulation-free range of the FSU3 as a function of level at the input mixer and the

set resolution bandwidth (useful signal offset = 1 MHz, DANL = -157 dBm /Hz, TOI = 25 dBm; typ. values at 2 GHz)

The optimum mixer level, i.e. the level at which the intermodulation distance is at its maximum, depends on the bandwidth. At a resolution bandwidth of 10 Hz, it is approx. –42 dBm and at 10 kHz increases to approx. -32 dBm.

Operating Manual 1313.9646.12 - 02 2.7

R&S FSU Getting Started

Measuring the Spectra of Complex Signals

Phase noise has a considerable influence on the intermodulation-free range at carrier offsets between 10 and 100 kHz (Fig. 2.6). At greater bandwidths, the influence of the phase noise is greater than it would be with small bandwidths. The optimum mixer level at the bandwidths under consideration becomes almost independent of bandwidth and is approx. –40 dBm.

Distortion free dynamic range

-60

-70

-80

-90

-100

Dynamic range dB

-110

-120

-60-50 -40-30-20-10

10 to 100 kHz offset

RBW=10 kHz

RBW=1 kHz

RBW=100 Hz

RBW=10 Hz

Mixe r lev el

T.O.I

Thermal noise

Fig. 2.6 Intermodulation-free dynamic range of the FSU3 as a function of level at the input mixer

and of the selected resolution bandwidth (useful signal offset = 10 to 100 kHz, DANL = 157 dBm /Hz, TOI = 25 dBm; typ. values at 2 GHz).

If the intermodulation products of a DUT with a very high dynamic range are to be measured and the resolution bandwidth to be used is therefore very small, it is best to measure the levels of the useful signals and those of the intermodulation products separately using a small span. The measurement time will be reduced– in particular if the offset of the useful signals is large. To find signals reliably when frequency span is small, it is best to synchronize the signal sources and the R&S FSU.

2.8 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measuring Signals in the Vicinity of Noise

2.3 Measuring Signals in the Vicinity of Noise

The minimum signal level a Spectrum Analyzer can measure is limited by its intrinsic noise. Small signals can be swamped by noise and therefore cannot be measured. For signals that are just above the intrinsic noise, the accuracy of the level measurement is influenced by the intrinsic noise of the R&S FSU.

The displayed noise level of a Spectrum Analyzer depends on its noise figure, the selected RF attenuation, the selected reference level, the selected resolution and video bandwidth and the detector. The effect of the different parameters is explained in the following.

Impact of the RF attenuation setting

The sensitivity of a Spectrum Analyzer is directly influenced by the selected RF attenuation. The highest sensitivity is obtained at a RF attenuation of 0 dB. The R&S FSU’s RF attenuation can be set in 5 dB steps up to 70 dB (5 dB steps up to 75 dB with option Electronic Attenuator R&S FSU-B25). Each additional 5 dB step reduces the R&S FSU’s sensitivity by 10 dB, i.e. the displayed noise is increased by 5 dB.

Impact of the reference level setting

If the reference level is changed, the R&S FSU changes the gain on the last IF so that the voltage at the logarithmic amplifier and the A/D converter is always the same for signal levels corresponding to the reference level. This ensures that the dynamic range of the log amp or the A/D converter is fully utilized. Therefore, the total gain of the signal path is low at high reference levels and the noise figure of the IF amplifier makes a substantial contribution to the total noise figure of the R&S FSU. The figure below shows the change in the displayed noise depending on the set reference level at 10 kHz and 300 kHz resolution bandwidth. With digital bandwidths (≤100 kHz) the noise increases sharply at high reference levels because of the dynamic range of the A/D converter.

rel. noise level /dB

RBW = 10 kHz

RBW = 300 kH

-2

-70-60-50-40-30-20-1 Reference l evel / dBm

Fig. 2.7 Change in displayed noise as a function of the selected reference level at bandwidths of

10 kHz and 300 kHz (-30 dBm reference level)

Operating Manual 1313.9646.12 - 02 2.9

R&S FSU Getting Started

Measuring Signals in the Vicinity of Noise

Impact of the resolution bandwidth

The sensitivity of a Spectrum Analyzer also directly depends on the selected bandwidth. The highest sensitivity is obtained at the smallest bandwidth (for the R&S FSU: 10 Hz, for FFT filtering: 1 Hz). If the bandwidth is increased, the reduction in sensitivity is proportional to the change in bandwidth. The R&S FSU has bandwidth settings in 2, 3, 5, 10 sequence. Increasing the bandwidth by a factor of 3 increases the displayed noise by approx. 5 dB (4.77 dB precisely). If the bandwidth is increased by a factor of 10, the displayed noise increases by a factor of 10, i.e. 10 dB. Because of the way the resolution filters are designed, the sensitivity of Spectrum Analyzers often depends on the selected resolution bandwidth. In data sheets, the displayed average noise level is often indicated for the smallest available bandwidth (for the R&S FSU: 10 Hz). The extra sensitivity obtained if the bandwidth is reduced may therefore deviate from the values indicated above. The following table illustrates typical deviations from the noise figure for a resolution bandwidth of 10 kHz which is used as a reference value (= 0 dB).

Noi se f i gur

offset /dB

digital RB

-1 0, 01 0, 1 1 10 100 1000

Fig. 2.8 Change in R&S FSU noise figure at various bandwidths. The reference bandwidth is 10

kHz

analog RB

RBW /kHz

Impact of the video bandwidth

The displayed noise of a Spectrum Analyzer is also influenced by the selected video bandwidth. If the video bandwidth is considerably smaller than the resolution bandwidth, noise spikes are suppressed, i.e. the trace becomes much smoother. The level of a sinewave signal is not influenced by the video bandwidth. A sinewave signal can therefore be freed from noise by using a video bandwidth that is small compared with the resolution bandwidth, and thus be measured more accurately.

Impact of the detector

Noise is evaluated differently by the different detectors. The noise display is therefore influenced by the choice of detector. Sinewave signals are weighted in the same way by all detectors, i.e. the level display for a sinewave RF signal does not depend on the selected detector, provided that the signal-to-noise ratio is high enough. The measurement accuracy for signals in the vicinity of R&S FSU intrinsic noise is also influenced by the detector which has been selected. The R&S FSU has the following detectors:

2.10 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measuring Signals in the Vicinity of Noise

Maximum peak detector

If the max. peak detector s selected, the largest noise display is obtained, since the R&S FSU displays the highest value of the IF envelope in the frequency range assigned to a pixel at each pixel in the trace. With longer sweep times, the trace indicates higher noise levels since the probability of obtaining a high noise amplitude increases with the dwell time on a pixel. For short sweep times, the display approaches that of the sample detector since the dwell time on a pixel is only sufficient to obtain an instantaneous value.

Minimum peak detector

The min. peak detector indicates the minimum voltage of the IF envelope in the frequency range assigned to a pixel at each pixel in the trace. The noise is strongly suppressed by the minimum peak detector since the lowest noise amplitude that occurs is displayed for each test point. If the signal-to-noise ratio is low, the minimum of the noise overlaying the signal is displayed too low.

At longer sweep times, the trace shows smaller noise levels since the probability of obtaining a low noise amplitude increases with the dwell time on a pixel. For short sweep times, the display approaches that of the sample detector since the dwell time on a pixel is only sufficient to obtain an instantaneous value.

Autopeak detector

The Autopeak detector displays the maximum and minimum peak value at the same time. Both values are measured and their levels are displayed on the screen joint by a vertical line.

Sample detector

The sample detector samples the logarithm of the IF envelope for each pixel of the trace only once and displays the resulting value. If the frequency span of the R&S FSU is considerably higher than the resolution bandwidth (span/RBW >500), there is no guarantee that useful signals will be detected. They are lost due to undersampling. This does not happen with noise because in this case it is not the instantaneous amplitude that is relevant but only the probability distribution.

RMS detector

For each pixel of the trace, the RMS detector outputs the RMS value of the IF envelope for the frequency range assigned to each test point. It therefore measures noise power. The display for small signals is, however, the sum of signal power and noise power. For short sweep times, i.e. if only one uncorrelated sample value contributes to the RMS value measurement, the RMS detector is equivalent to the sample detector. If the sweep time is longer, more and more uncorrelated RMS values contribute to the RMS value measurement. The trace is, therefore, smoothed. The level of sinewave signals is only displayed correctly if the selected resolution bandwidth (RBW) is at least as wide as the frequency range which corresponds to a pixel in the trace. At a resolution bandwidth of 1 MHz, this means that the maximum frequency display range is 625 MHz.

Operating Manual 1313.9646.12 - 02 2.11

R&S FSU Getting Started

Measuring Signals in the Vicinity of Noise

Average detector

For each pixel of the trace, the average detector outputs the average value of the linear IF envelope for the frequency range assigned to each test point. It therefore measures the linear average noise. The level of sinewave signals is only displayed correctly if the selected resolution bandwidth (RBW) is at least as wide as the frequency range which corresponds to a pixel in the trace. At a resolution bandwidth of 1 MHz, this means the maximum frequency display range is 625 MHz.

Quasi peak detector

The quasi peak detector is a peak detector for EMI measurements with defined charge and discharge times. These times are defined in CISPR 16, the standard for equipment used to measure EMI emissions.

2.12 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measuring Signals in the Vicinity of Noise

2.3.1 Measurement example – Measuring the level of the internal reference generator at low S/N ratios

The example shows the different factors influencing the S/N ratio.

1. Set the R&S FSU to its default state.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Switch on the internal reference generator

➢ Press the SETUP key. ➢ Press the softkeys SERVICE - INPUT CAL.

The internal 128 MHz reference generator is on. The R&S FSU’s RF input is off.

3. Set the center frequency to 128 MHz and the frequency span to 100 MHz.

➢ Press the FREQ key and enter 128 MHz. ➢ Press the SPAN key and enter 100 MHz.

4. Set the RF attenuation to 60 dB to attenuate the input signal or to increase

the intrinsic noise.

➢ Press the AMPT key. ➢ Press the RF ATTEN MANUAL softkey and enter 60 dB.

The RF attenuation indicator is marked with an asterisk (*Att 60 dB) to show that it is no longer coupled to the reference level. The high input attenuation reduces the reference signal which can no longer be detected in noise.

Fig. 2.9 Sinewave signal with low S/N ratio. The signal is measured with the autopeak

Operating Manual 1313.9646.12 - 02 2.13

detector and is completely swamped by the intrinsic noise of the R&S FSU.

R&S FSU Getting Started

Measuring Signals in the Vicinity of Noise

5. To suppress noise spikes the trace can be averaged.

➢ Press the TRACE key. ➢ Press the AVERAGE softkey.

The traces of consecutive sweeps are averaged. To perform averaging, the R&S FSU automatically switches on the sample detector. The RF signal, therefore, can be more clearly distinguished from noise.

Fig. 2.10 RF sinewave signal with low S/N ratio if the trace is averaged.

6. Instead of trace averaging, a video filter that is narrower than the resolution

bandwidth can be selected.

➢ Press the CLEAR/WRITE softkey in the trace menu. ➢ Press the BW key.

Press the VIDEO BW MANUAL softkey and enter 10 kHz. The RF signal can be more clearly distinguished from noise.

Fig. 2.11 RF sinewave signal with low S/N ratio if a smaller video bandwidth is selected.

2.14 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measuring Signals in the Vicinity of Noise

7. By reducing the resolution bandwidth by a factor of 10, the noise is reduced

by 10 dB.

➢ Press the RES BW MANUAL softkey and enter 300 kHz.

The displayed noise is reduced by approx. 10 dB. The signal, therefore, emerges from noise by about 10 dB. Compared to the previous setting, the video bandwidth has remained the same, i.e. it has increased relative to the smaller resolution bandwidth. The averaging effect is, therefore, reduced by the video bandwidth. The trace will be noisier.

Fig. 2.12 Reference signal at a smaller resolution bandwidth

Operating Manual 1313.9646.12 - 02 2.15

R&S FSU Getting Started

Noise Measurements

2.4 Noise Measurements

Noise measurements play an important role in spectrum analysis. Noise e.g. affects the sensitivity of radio communication systems and their components.

Noise power is specified either as the total power in the transmission channel or as the power referred to a bandwidth of 1 Hz. The sources of noise are, for example, amplifier noise or noise generated by oscillators used for the frequency conversion of useful signals in receivers or transmitters. The noise at the output of an amplifier is determined by its noise figure and gain.

The noise of an oscillator is determined by phase noise near the oscillator frequency and by thermal noise of the active elements far from the oscillator frequency. Phase noise can mask weak signals near the oscillator frequency and make them impossible to detect.

2.4.1 Measuring noise power density

To measure noise power referred to a bandwidth of 1 Hz at a certain frequency, the R&S FSU has an easy-to-use marker function. This marker function calculates the noise power density from the measured marker level.

2.4.1.1 Measurement example – Measuring the intrinsic noise power density of the R&S FSU at 1 GHz and calculating the R&S FSU’s noise figure

1. Set the R&S FSU to its default state.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set the center frequency to 1 GHz and the span to 1 MHz.

➢ Press the FREQ key and enter 1 GHz. ➢ Press the SPAN key and enter 1 MHz.

3. Switch on the marker and set the marker frequency to 1 GHz.

➢ Press the MKR key and enter 1 GHz.

4. Switch on the noise marker function.

➢ Press the MEAS key. ➢ Press the NOISE MARKER softkey.

The R&S FSU displays the noise power at 1 GHz in dBm (1Hz).

Since noise is random, a sufficiently long measurement time has to be selected to obtain stable measurement results. This can be achieved by averaging the trace or by selecting a very small video bandwidth relative to the resolution bandwidth.

5. The measurement result is stabilized by averaging the trace

➢ Press the TRACE key. ➢ Press the AVERAGE softkey.

The R&S FSU performs sliding averaging over 10 traces from consecutive sweeps. The measurement result becomes more stable.

2.16 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Noise Measurements

Conversion to other reference bandwidths

The result of the noise measurement can be referred to other bandwidths by simple conversion. This is done by adding 10 · log (BW) to the measurement result, BW being the new reference bandwidth.

Example:

A noise power of –150 dBm (1 Hz) is to be referred to a bandwidth of 1 kHz. P

= -150 + 10 · log (1000) = -150 +30 = -120 dBm(1 kHz)

[1kHz]

Calculation method:

The following method is used to calculate the noise power:

If the noise marker is switched on, the R&S FSU automatically activates the sample detector. The video bandwidth is set to 1/10 of the selected resolution bandwidth (RBW).

To calculate the noise, the R&S FSU takes an average over 17 adjacent pixels (the pixel on which the marker is positioned and 8 pixels to the left, 8 pixels to the right of the marker). The measurement result is stabilized by video filtering and averaging over 17 pixels.

Since both video filtering and averaging over 17 trace points is performed in the log display mode, the result would be 2.51 dB too low (difference between logarithmic noise average and noise power). The R&S FSU, therefore, corrects the noise figure by 2.51 dB.

To standardize the measurement result to a bandwidth of 1 Hz, the result is also corrected by –10 · log (RBW

), with RBW

noise

being the power bandwidth of the

noise

selected resolution filter (RBW).

Detector selection

The noise power density is measured in the default setting with the sample detector and using averaging. Other detectors that can be used to perform a measurement giving true results are the average detector or the RMS detector. If the average detector is used, the linear video voltage is averaged and displayed as a pixel. If the RMS detector is used, the squared video voltage is averaged and displayed as a pixel. The averaging time depends on the selected sweep time (=SWT/625). An increase in the sweep time gives a longer averaging time per pixel and thus stabilizes the measurement result. The R&S FSU automatically corrects the measurement result of the noise marker display depending on the selected detector (+1.05 dB for the average detector, 0 dΒ for the RMS detector). It is assumed that the video bandwidth is set to at least three times the resolution bandwidth. While the average or RMS detector is being switched on, the R&S FSU sets the video bandwidth to a suitable value.

The Pos Peak, Neg Peak, Auto Peak and Quasi Peak detectors are not suitable for measuring noise power density.

Operating Manual 1313.9646.12 - 02 2.17

R&S FSU Getting Started

Noise Measurements

Determining the noise figure:

The noise figure of amplifiers or of the R&S FSU alone can be obtained from the noise power display. Based on the known thermal noise power of a 50 Ω resistor at room temperature (-174 dBm (1Hz)) and the measured noise power P

noise

the noise

figure (NF) is obtained as follows:

NF = P

+ 174 – g,

noise

where g = gain of DUT in dB

Example:

The measured internal noise power of the R&S FSU at an attenuation of 0 dB is found to be –155 dBm/1 Hz. The noise figure of the R&S FSU is obtained as follows

NF = -155 + 174 = 19 dB

If noise power is measured at the output of an amplifier, for example, the sum of the internal noise power and the noise power at the output of the DUT is measured. The noise power of the DUT can be obtained by subtracting the internal noise power from the total power (subtraction of linear noise powers). By means of the following diagram, the noise level of the DUT can be estimated from the level difference between the total and the internal noise level.

Fig. 2.13 Correction factor for measured noise power as a function of the ratio of total power to

the intrinsic noise power of the R&S FSU.

2.18 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Noise Measurements

2.4.2 Measurement of Noise Power within a Transmission Channel

Noise in any bandwidth can be measured with the channel power measurement functions. Thus the noise power in a communication channel can be determined, for example. If the noise spectrum within the channel bandwidth is flat, the noise marker from the previous example can be used to determine the noise power in the channel by considering the channel bandwidth. If, however, phase noise and noise that normally increases towards the carrier is dominant in the channel to be measured, or if there are discrete spurious signals in the channel, the channel power measurement method must be used to obtain correct measurement results.

2.4.2.1 Measurement Example – Measuring the intrinsic noise of the R&S FSU at 1 GHz in a 1.23 MHz channel bandwidth with the channel power function

Test setup:

The RF input of the R&S FSU remains open-circuited or is terminated with 50 Ω.

Measurement with the R&S FSU:

1. Set the R&S FSU to its default state.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set the center frequency to 1 GHz and the span to 2 MHz.

➢ Press the FREQ key and enter 1 GHz. ➢ Press the SPAN key and enter 2 MHz.

3. To obtain maximum sensitivity, set RF attenuation on the R&S FSU to 0 dB.

➢ Press the AMPT key. ➢ Press the RF ATTEN MANUAL softkey and enter 0 dB.

4. Switch on and configure the channel power measurement.

➢ Press the MEAS key. ➢ Press the CHAN POWER ACP softkey.

The R&S FSU activates the channel or adjacent channel power measurement according to the currently set configuration.

➢ Press the CP/ACP CONFIG ! softkey.

The R&S FSU enters the submenu for configuring the channel.

➢ Press the CHANNEL BANDWIDTH softkey and enter 1.23 MHz.

The R&S FSU displays the 1.23 MHz channel as two vertical lines which are symmetrical to the center frequency.

➢ Press the PREV key.

The R&S FSU returns to the main menu for channel and adjacent channel power measurement.

➢ Press the ADJUST SETTINGS softkey.

The settings for the frequency span, the bandwidth (RBW and VBW) and the detector are automatically set to the optimum values required for the measurement.

Operating Manual 1313.9646.12 - 02 2.19

R&S FSU Getting Started

Noise Measurements

Fig. 2.14 Measurement of the R&S FSU’s intrinsic noise power in a 1.23 MHz channel

bandwidth.

5. Stabilizing the measurement result by increasing the sweep time

➢ Press the SWEEP TIME softkey and enter 1 s.

By increasing the sweep time to 1 s, the trace becomes much smoother thanks to the RMS detector and the channel power measurement display is much more stable.

6. Referring the measured channel power to a bandwidth of 1 Hz

➢ Press the CHAN PWR / Hz softkey.

The channel power is referred to a bandwidth of 1 Hz. The measurement is corrected by -10 · log (ChanBW), with ChanBW being the channel bandwidth that was selected.

Method of calculating the channel power

When measuring the channel power, the R&S FSU integrates the linear power which corresponds to the levels of the pixels within the selected channel. The R&S FSU uses a resolution bandwidth which is far smaller than the channel bandwidth. When sweeping over the channel, the channel filter is formed by the passband characteristics of the resolution bandwidth (see Fig. 2.15).

-3 dB

Resolution filter

Sweep

Channel bandwith

Fig. 2.15 Approximating the channel filter by sweeping with a small resolution bandwidth

2.20 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Noise Measurements

The following steps are performed:

• The linear power of all the trace pixels within the channel is calculated.

= 10

(Li/10)

P where P

= power of the trace pixel i

= displayed level of trace point i

• The powers of all trace pixels within the channel are summed up and the sum is

divided by the number of trace pixels in the channel.

• The result is multiplied by the quotient of the selected channel bandwidth and the

noise bandwidth of the resolution filter (RBW).

Since the power calculation is performed by integrating the trace within the channel bandwidth, this method is also called the IBW method (Integration Bandwidth method).

Bandwidth selection (RBW)

For channel power measurements, the resolution bandwidth (RBW) must be small compared to the channel bandwidth, so that the channel bandwidth can be defined precisely. If the resolution bandwidth which has been selected is too wide, this may have a negative effect on the selectivity of the simulated channel filter and result in the power in the adjacent channel being added to the power in the transmit channel. A resolution bandwidth equal to 1% to 3% of the channel bandwidth should, therefore, be selected. If the resolution bandwidth is too small, the required sweep time becomes too long and the measurement time increases considerably.

Detector selection

Since the power of the trace is measured within the channel bandwidth, only the sample detector and RMS detector can be used. These detectors provide measured values that make it possible to calculate the real power. The peak detectors (Pos Peak, Neg Peak and Auto Peak) are not suitable for noise power measurements as no correlation can be established between the peak value of the video voltage and power.

With the sample detector, a value (sample) of the IF envelope voltage is displayed at each trace pixel. Since the frequency spans are very large compared with the resolution bandwidth (span/RBW >500), sinewave signals present in the noise might be lost, i.e. they are not displayed. This is not important for pure noise signals, however, since a single sample in itself is not important - it is the probability distribution of all measured values that counts. The number of samples for power calculation is limited to the number of trace pixels (625 for the R&S FSU).

To increase the repeatability of measurements, averaging is often carried out over several traces (AVERAGE softkey in the TRACE menu). This gives spurious results for channel power measurements (max. –2.51 dB for ideal averaging). Trace averaging should, therefore, be avoided.

With the RMS detector, the whole IF envelope is used to calculate the power for each trace pixel. The IF envelope is digitized using a sampling frequency which is at least five times the resolution bandwidth which has been selected. Based on the sample values, the power is calculated for each trace pixel using the following formula:

Operating Manual 1313.9646.12 - 02 2.21

R&S FSU Getting Started

Noise Measurements

RMS

= linear digitized video voltage at the output of the A/D converter

----

×=

∑

i1=

N = number of A/D converter values per pixel of the trace

= power represented by a trace pixel

RMS

When the power has been calculated, the power units are converted into decibels and the value is displayed as a trace pixel.

The number of A/D converter values, N, used to calculate the power, is defined by the sweep time. The time per trace pixel for power measurements is directly proportional to the selected sweep time. The RMS detector uses far more samples for power measurement than the sample detector, especially if the sweep time is increased. The measurement uncertainty can be reduced considerably. In the default setting, the R&S FSU therefore uses the RMS detector to measure the channel power.

For both detectors (sample and RMS), the video bandwidth (VBW) must at least be three times the resolution bandwidth, so that the peak values of the video voltage are not cut off by the video filter. At smaller video bandwidths, the video signal is averaged and the power readout will be too small.

Sweep time selection

If the sample detector is used, it is best to select the smallest sweep time possible for a given span and resolution bandwidth. The minimum time is obtained if the setting is coupled. This means that the time per measurement is minimal. Extending the measurement time does not have any advantages as the number of samples for calculating the power is defined by the number of trace pixels in the channel.

When using the RMS detector, the repeatability of the measurement results can be influenced by the selection of sweep times. Repeatability is increased at longer sweep times.

Repeatability can be estimated from the following diagram:

2.22 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Noise Measurements

max. error/dB

95 % Confidence

0.5

1.5

2.5

level

99 % Confidence

level

Fig. 2.16 Repeatability of channel power measurements as a function of the number of samples

used for power calculation

100

1000

10000

Number of samples

100000

The curves in Fig. 2.16 indicates the repeatability obtained with a probability of 95% and 99% depending on the number of samples used.

The repeatability with 600 samples is ± 0.5 dB. This means that – if the sample detector and a channel bandwidth over the whole diagram (channel bandwidth = span) is used - the measured value lies within ± 0.5 dB of the true value with a probability of 99%.

If the RMS detector is used, the number of samples can be estimated as follows:

Since only uncorrelated samples contribute to the RMS value, the number of samples can be calculated from the sweep time and the resolution bandwidth.

Samples can be assumed to be uncorrelated if sampling is performed at intervals of 1/RBW. The number of uncorrelated samples (N

= SWT × RBW

decorr

The number of uncorrelated samples per trace pixel is obtained by dividing N

) is calculated as follows:

decorr

by 625 (= pixels per trace).

Example:

At a resolution bandwidth of 30 kHz and a sweep time of 100 ms, 3000 uncorrelated samples are obtained. If the channel bandwidth is equal to the frequency display range, i.e. all trace pixels are used for the channel power measurement, a repeatability of 0.2 dB with a confidence level of 99% is the estimate that can be derived from Fig. 2.16.

Operating Manual 1313.9646.12 - 02 2.23

R&S FSU Getting Started

Noise Measurements

2.4.3 Measuring Phase Noise

The R&S FSU has an easy-to-use marker function for phase noise measurements. This marker function indicates the phase noise of an RF oscillator at any carrier in dBc in a bandwidth of 1 Hz.

2.4.3.1 Measurement Example – Measuring the phase noise of a signal generator at a carrier offset of 10 kHz

Test setup:

Settings on the signal generator (e.g. R&S SMIQ):

Frequency: 100 MHz

Level: 0 dBm

Measurement using R&S FSU:

1. Set the R&S FSU to its default state

➢ Press the PRESET key.

R&S FSU is in its default state.

2. Set the center frequency to 100 MHz and the span to 50 kHz

➢ Press the FREQ key and enter 100 MHz. ➢ Press the SPAN key and enter 50 kHz.

3. Set the R&S FSU’s reference level to 0 dBm (=signal generator level)

➢ Press the AMPT key and enter 0 dBm.

4. Enable phase noise measurement

➢ Press the MKR FCTN key. ➢ Press the PHASE NOISE ! softkey.

The R&S FSU activates phase noise measurement. Marker 1 (=main marker) and marker 2 (= delta marker) are positioned on the signal maximum. The position of the marker is the reference (level and frequency) for the phase noise measurement. A horizontal line represents the level of the reference point and a vertical line the frequency of the reference point. Data entry for the delta marker is activated so that the frequency offset at which the phase noise is to be measured can be entered directly.

5. 10 kHz frequency offset for determining phase noise.

➢ Enter 10 kHz.

The R&S FSU displays the phase noise at a frequency offset of 10 kHz. The magnitude of the phase noise in dBc/Hz is displayed in the delta marker output field at the top right of the screen (delta 2 [T1 PHN]).

2.24 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Noise Measurements

6. Stabilize the measurement result by activating trace averaging.

➢ Press the TRACE key. ➢ Press the AVERAGE softkey.

Fig. 2.17 Measuring phase noise with the phase-noise marker function

The frequency offset can be varied by moving the marker with the spinwheel or by entering a new frequency offset as a number.

Operating Manual 1313.9646.12 - 02 2.25

R&S FSU Getting Started

Measurements on Modulated Signals

2.5 Measurements on Modulated Signals

If RF signals are used to transmit information, an RF carrier is modulated. Analog modulation methods such as amplitude modulation, frequency modulation and phase modulation have a long history and digital modulation methods are now used for modern systems. Measuring the power and the spectrum of modulated signals is an important task to assure transmission quality and to ensure the integrity of other radio services. This task can be performed easily with a Spectrum Analyzer. Modern Spectrum Analyzers also provide the test routines that are essential to simplify complex measurements.

2.5.1 Measurements on AM signals

The R&S FSU detects the RF input signal and displays the magnitudes of its components as a spectrum. AM modulated signals are also demodulated by this process. The AF voltage can be displayed in the time domain if the modulation sidebands are within the resolution bandwidth. In the frequency domain, the AM sidebands can be resolved with a small bandwidth and can be measured separately. This means that the modulation depth of a carrier modulated with a sinewave signal can be measured. Since the dynamic range of a Spectrum Analyzer is very wide, even extremely small modulation depths can be measured accurately. The R&S FSU has a test routine which measures the modulation depth in %.

2.5.1.1 Measurement Example 1 – Displaying the AF of an AM signal in the time domain

Test setup:

Settings on the signal generator (e.g. R&S SMIQ):

Frequency: 100 MHz

Level: 0 dBm

Modulation: 50 % AM, 1 kHz AF

Measurement with the R&S FSU:

1. Set the R&S FSU to its default state

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set the center frequency to 100 MHz and the span to 0 kHz

➢ Press the FREQ key and enter 100 MHz. ➢ Press the SPAN key and enter 0 Hz.

3. Set the reference level to +6 dBm and the display range to linear

➢ Press the AMPT key and enter 6 dBm. ➢ Press the RANGE LINEAR softkey.

2.26 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

4. Use the video trigger to trigger on the AF signal in order to obtain a

stationary display

➢ Press the TRIG key. ➢ Press the VIDEO softkey.

The video trigger level is set to 50% if the instrument is switched on for the first time. The trigger level is displayed as a horizontal line across the graph. The R&S FSU displays the 1 kHz AF signal stably in the time domain.

Fig. 2.18 Measuring the AF signal from a 1 kHz AM carrier

The AM/FM demodulator in the R&S FSU can be used to output the AF by means of a loudspeaker.

5. Switch on the internal AM demodulator

➢ Press the MKR FCTN key. ➢ Press the MKR DEMOD softkey.

The R&S FSU switches the AM demodulator on automatically.

➢ Turn up volume control.

A 1 kHz tone is output by the loudspeaker.

2.5.1.2 Measurement Example 2 – Measuring the modulation depth of an AM carrier in the frequency domain

Test setup:

Settings on the signal generator (e.g. R&S SMIQ):

Frequency: 100 MHz

Level: -30 dBm

Modulation: 50 % AM, 1 kHz AF

Operating Manual 1313.9646.12 - 02 2.27

R&S FSU Getting Started

Measurements on Modulated Signals

Measurement with the R&S FSU:

1. Set the R&S FSU to its default state

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set the center frequency to 100 MHz and the span to 0 kHz

➢ Press the FREQ key and enter 100 MHz. ➢ Press the SPAN key and enter 5 kHz.

3. Activate the marker function for AM depth measurement

➢ Press the MEAS key. ➢ Press the MODULATION DEPTH softkey.

The R&S FSU automatically positions a marker on the carrier signal in the middle of the graph and one delta marker on each of the lower and upper AM sidebands. The R&S FSU calculates the AM modulation depth from the ratios of the delta marker levels to the main marker level and outputs the numerical value in the marker info field

Fig. 2.19 Measurement of AM modulation depth. The modulation depth is indicated by

MDEPTH = 49.345 %. The frequency of the AF signal is indicated by the delta markers

2.28 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

2.5.2 Measurements on FM Signals

Since Spectrum Analyzers only display the magnitude of signals by means of the envelope detector, the modulation of FM signals cannot be directly measured as is the case with AM signals. With FM signals, the voltage at the output of the envelope detector is constant as long as the frequency deviation of the signal is within the flat part of the passband characteristic of the resolution filter which has been selected. Amplitude variations can only occur if the current frequency lies on the falling edge of the filter characteristic. This effect can be used to demodulate FM signals. The center frequency of the R&S FSU is set in a way that the nominal frequency of the test signal is on the filter edge (below or above the center frequency). The resolution bandwidth and the frequency offset are selected in a way that the current frequency is on the linear part of the filter slope. The frequency variation of the FM signal is then transformed into an amplitude variation which can be displayed in the time domain.

The R&S FSU's analog 5 have a good filter-slope linearity, if the frequency of the R&S FSU is set to 1.2 times the filter bandwidth below or above the frequency of the transmit signal. The useful range for FM demodulation is then almost equal to the resolution bandwidth.

order filters with frequencies from 200 kHz to 3 MHz

2.5.2.1 Measurement Example – Displaying the AF of an FM carrier

Test setup:

Settings on the signal generator (e.g. R&S SMIQ):

Frequency: 100 MHz

Level: -30 dBm

Modulation: FM 0 kHz deviation (i.e., FM = off), 1 kHz AF

Measurement with the R&S FSU:

1. Set the R&S FSU to its default state

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set the center frequency to 99.64 MHz and the span to 300 kHz.

➢ Press the FREQ key and enter 99.64 MHz. ➢ Press the SPAN key and enter 300 kHz.

3. Set a resolution bandwidth of 300 kHz.

➢ Press the BW key. ➢ Press the RES BW MANUAL softkey and enter 300 kHz.

Operating Manual 1313.9646.12 - 02 2.29

R&S FSU Getting Started

Measurements on Modulated Signals

4. Set a display range of 20 dB and shift the filter characteristics to the middle

of the display.

➢ Press the AMPT key. ➢ Press the RANGE LOG MANUAL softkey and enter 20 dB. ➢ Press the NEXT key. ➢ Set the GRID softkey to REL. ➢ Press the PREV softkey. ➢ Using the spinwheel, shift the reference level so that the filter edge intersects

the - 10 dB level line at the center frequency.

The slope of the 300 kHz filter is displayed. This corresponds to the demodulator characteristics for FM signals with a slope of approx. 5 dB/100 kHz.

Fig. 2.20 Filter edge of a 300 kHz filter used as an FM-discriminator characteristic

5. Set an FM deviation of 100 kHz and an AF of 1 kHz on the signal generator

6. Set a frequency deviation of 0 Hz on the R&S FSU

➢ Press the SPAN key. ➢ Press the ZERO SPAN.

The demodulated FM signal is displayed. The signal moves across the screen.

7. Creating a stable display by video triggering

➢ Press the TRIG key. ➢ Press the VIDEO softkey.

A stationary display is obtained for the FM AF signal

Result: (-10 ±5) dB; this means that a deviation of 100 kHz is obtained if the demodulator characteristic slope is 5 dB/100 kHz

2.30 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

Fig. 2.21 Demodulated FM signal

2.5.3 Measuring Channel Power and Adjacent Channel Power

Measuring channel power and adjacent channel power is one of the most important tasks in the field of digital transmission for a Spectrum Analyzer with the necessary test routines. While, theoretically, channel power could be measured at highest accuracy with a power meter, its low selectivity means that it is not suitable for measuring adjacent channel power as an absolute value or relative to the transmit channel power. The power in the adjacent channels can only be measured with a selective power meter.

A Spectrum Analyzer cannot be classified as a true power meter, because it displays the IF envelope voltage. However, it is calibrated such as to correctly display the power of a pure sinewave signal irrespective of the selected detector. This calibration is not valid for non-sinusoidal signals. Assuming that the digitally modulated signal has a Gaussian amplitude distribution, the signal power within the selected resolution bandwidth can be obtained using correction factors. These correction factors are normally used by the R&S FSU's internal power measurement routines in order to determine the signal power from IF envelope measurements. These factors are valid if and only if the assumption of a Gaussian amplitude distribution is correct.

Apart from this common method, the R&S FSU also has a true power detector, i.e. an RMS detector. It correctly displays the power of the test signal within the selected resolution bandwidth irrespective of the amplitude distribution, without additional correction factors being required. With an absolute measurement uncertainty of <

0.3 dB and a relative measurement uncertainty of < 0.1 dB (each with a confidence level of 95%), the R&S FSU comes close to being a true power meter.

There are two possible methods for measuring channel and adjacent channel power with a Spectrum Analyzer:

The IBW method (Integration Bandwidth Method) in which the R&S FSU measures with a resolution bandwidth that is less than the channel bandwidth and integrates the level values of the trace versus the channel bandwidth. This method is described in the section on noise measurements.

Operating Manual 1313.9646.12 - 02 2.31

R&S FSU Getting Started

Measurements on Modulated Signals

Measurement using a channel filter.

In this case, the R&S FSU makes measurements in the time domain using an IF filter that corresponds to the channel bandwidth. The power is measured at the output of the IF filter. Until now, this method has not been used for Spectrum Analyzers, because channel filters were not available and the resolution bandwidths, optimized for the sweep, did not have a sufficient selectivity. The method was reserved for special receivers optimized for a particular transmission method.

The R&S FSU has test routines for simple channel and adjacent channel power measurements. These routines give quick results without any complex or tedious setting procedures.

2.5.3.1 Measurement Example 1 – ACPR measurement on an IS95 CDMA Signal

Test setup:

Settings on the signal generator (e.g. R&S SMIQ):

Frequency: 850 MHz

Level: 0 dBm

Modulation: CDMA IS 95

Measurement with the R&S FSU:

1. Set the R&S FSU to its default state.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set the center frequency to 850 MHz and frequency deviation to 4 MHz.

➢ Press the FREQ key and enter 850 MHz.

3. Set the reference level to +10 dBm.

➢ Press the AMPT key and enter 10 dBm.

4. Configuring the adjacent channel power for the CDMA IS95 reverse link.

➢ Press the MEAS key. ➢ Press the CHAN PWR ACP ! softkey.

2.32 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

➢ Press the CP/ACP STANDARD softkey.

From the list of standards, select CDMA IS95A REV using the spinwheel or the cursor down key below the spinwheel and press ENTER.

The R&S FSU sets the channel configuration according to the IS95 standard for mobile stations with 2 adjacent channels above and below the transmit channel. The spectrum is displayed in the upper part of the screen, the numeric values of the results and the channel configuration in the lower part of the screen. The various channels are represented by vertical lines on the graph. The frequency span, resolution bandwidth, video bandwidth and detector are selected automatically to give correct results. To obtain stable results especially in the adjacent channels (30 kHz bandwidth) which are narrow in comparison with the transmission channel bandwidth (1.23 MHz) - the RMS detector is used.

5. Set the optimal reference level and RF attenuation for the applied signal

level.

➢ Press the ADJUST REF LVL softkey.

The R&S FSU sets the optimal RF attenuation and the reference level based on the transmission channel power to obtain the maximum dynamic range. The following figure shows the result of the measurement.

Fig. 2.22 Adjacent channel power measurement on a CDMA IS95 signal

The repeatability of the results, especially in the narrow adjacent channels, strongly depends on the measurement time since the dwell time within the 10 kHz channels is only a fraction of the complete sweep time. A longer sweep time may increase the probability that the measured value converges to the true value of the adjacent channel power, but this increases measurement time.

Operating Manual 1313.9646.12 - 02 2.33

R&S FSU Getting Started

Measurements on Modulated Signals

To avoid long measurement times, the R&S FSU measures the adjacent channel power in the time domain (FAST ACP). In the FAST ACP mode, the R&S FSU measures the power of each channel at the defined channel bandwidth, while being tuned to the center frequency of the channel in question. The digital implementation of the resolution bandwidths makes it possible to select a filter characteristics that is precisely tailored to the signal. In case of CDMA IS95, the power in the useful channel is measured with a bandwidth of 1.23 MHz and that of the adjacent channels with a bandwidth of 30 kHz. Therefore the R&S FSU jumps from one channel to the other and measures the power at a bandwidth of 1.23 MHz or 30 kHz using the RMS detector. The measurement time per channel is set with the sweep time. It is equal to the selected measurement time divided by the selected number of channels. The five channels from the above example and the sweep time of 100 ms give a measurement time per channel of 20 ms.

Compared to the measurement time per channel given by the span (= 5.1 MHz) and sweep time (= 100 ms, equal to 0.600 ms per 30 kHz channel) used in the example, this is a far longer dwell time on the adjacent channels (factor of 12). In terms of the number of uncorrelated samples this means 20000/33 µs = 606 samples per channel measurement compared to 600/33µs = 12.5 samples per channel measurement.

Repeatability with a confidence level of 95% is increased from ± 1.4 dB to ±

0.38 dB as shown in Fig. 2.16. For the same repeatability, the sweep time would have to be set to 1.2 s with the integration method. The following figure shows the standard deviation of the results as a function of the sweep time.

ACPR Repeatability IS95

IBW Method

1,4

1,2

0,8

0,6

Standard dev / d

0,4

0,2

10 100 1000

Fig. 2.23 Repeatability of adjacent channel power measurement on IS95-standard signals

if the integration bandwidth method is used

Alternat e channel

Adjacent channel

Tx cha nnel

Sweep t ime/ms

6. Switch to Fast ACP to increase the repeatability of results.

➢ Press the CP/ACP CONFIG ! softkey. ➢ Set the FAST ACP softkey to ON. ➢ Press the ADJUST REF LVL softkey.

The R&S FSU measures the power of each channel in the time domain. The trace represents power as a function of time for each measured channel (see

Fig. 2.24). The numerical results from consecutive measurements are much

more stable.

2.34 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

Fig. 2.24 Measuring the channel power and adjacent channel power ratio for IS95 signals

in the time domain (Fast ACP)

The following figure shows the repeatability of power measurements in the transmit channel and of relative power measurements in the adjacent channels as a function of sweep time. The standard deviation of measurement results is calculated from 100 consecutive measurements as shown in Fig. 2.23. Take scaling into account if comparing power values.

ACPR IS95 Repeatability

0,35

0,3

0,25

0,2

0,15

Standard dev /dB

0,1

0,05

10 100 1000

Fig. 2.25 Repeatability of adjacent channel power measurements on IS95 signals in the

Fast ACP mode

Tx channel

Alternate channels

Adjacent channels

Sweep time/ms

Note on adjacent channel power measurements on IS95 base-station signals:

When measuring the adjacent channel power of IS95 base-station signals, the frequency spacing of the adjacent channel to the nominal transmit channel is specified as ±750 kHz. The adjacent channels are, therefore, so close to the transmit channel that the power of the transmit signal leaks across and is also measured in the adjacent channel if the usual method using the 30 kHz resolution bandwidth is applied. The reason is the low selectivity of the 30 kHz resolution filter. The resolution bandwidth, therefore, must be reduced considerably, e.g. to 3 kHz to avoid this. This causes very long measurement times (factor of 100 between a 30 kHz and 3 kHz resolution bandwidth).

This effect is avoided with the time domain method which uses steep IF filters. The 30 kHz channel filter implemented in the R&S FSU has a very high selectivity so that even with a ± 750 kHz spacing to the transmit channel the power of the useful modulation spectrum is not measured.

Operating Manual 1313.9646.12 - 02 2.35

R&S FSU Getting Started

Measurements on Modulated Signals

The following figure shows the passband characteristics of the 30 kHz channel filter in the R&S FSU.

Fig. 2.26 Frequency response of the 30 kHz channel filter for measuring the power in the IS 95

adjacent channel

2.5.3.2 Measurement Example 2 – Measuring the adjacent channel power of an IS136 TDMA signal

Test setup:

As the modulation spectrum of the IS136 signal leaks into the adjacent channel, it makes a contribution to the power in the adjacent channel. Exact tuning of the R&S FSU to the transmit frequency is therefore critical. If tuning is not precise, the adjacent channel power ratios in the lower and upper adjacent channels become asymmetrical. The R&S FSU’s frequency and the generator frequency are therefore synchronized.

Settings on the signal generator (e.g. R&S SMIQ):

Frequency: 850 MHz

Level: -20 dBm

Modulation: IS136/NADC

Measurement with the R&S FSU

1. Set the R&S FSU to its default state.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set up the R&S FSU for synchronization to an external reference frequency.

➢ Press the SETUP key. ➢ Set the REFERENCE softkey to EXT.

2.36 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

3. Set the center frequency to 850 MHz.

Press the FREQ key and enter 850 MHz.

4. Configure adjacent channel power measurement for IS136 signals.

➢ Press the MEAS key. ➢ Press the CHAN PWR ACP ! softkey. ➢ Press the CP/ACP STANDARD softkey. ➢ Select NADC IS136 from the list of standards and press ENTER.

The R&S FSU performs the power measurement in 5 channels (in the useful channel and in the two upper and two lower adjacent channels).

5. Setting the optimum reference level and RF attenuation for the

measurement

➢ Press the ADJUST REF LEVEL softkey.

The R&S FSU sets the optimum RF attenuation and the optimum reference level on the basis of the measured channel power.

Fig. 2.27 Measuring the relative adjacent channel power of an NADC signal in each of the

two adjacent channels below and above the transmit channel.

To increase repeatability – especially in the adjacent channels – the R&S FSU’s Fast ACP routine is recommended.

6. Switching on the Fast ACP routine.

➢ Press the CP/ACP CONFIG ! softkey ➢ Set the FAST ACP softkey to ON. ➢ Press the ADJUST REF LEVEL softkey.

The R&S FSU makes consecutive measurements on the 5 channels in the zero span mode using the receive filter specified in IS 136 to define the resolution bandwidth. The power in each channel is displayed on the graph as a function of time.

Operating Manual 1313.9646.12 - 02 2.37

R&S FSU Getting Started

Measurements on Modulated Signals

Fig. 2.28 Measuring adjacent channel power in time domain (Fast ACP)

As the resolution bandwidth is much wider than the one used for the integration method, the results are much more stable when compared at the same sweep time.

Repeatability can be influenced by the selected sweep time. The results become much more stable if long sweep times are selected. Since the amplitude distribution is different in different channels (part of the modulation spectrum falls within the first adjacent channel), the repeatability depends on the spacing of the measured channel from the transmit channel.

Fig. 2.29 below shows the standard deviation of results in the different

channels as a function of the selected sweep time. The standard deviation for the various sweep times was recorded using a signal generator as a source. With real DUTs the amplitude distributions in adjacent channels may be different so that the standard deviation could differ from that shown in Fig. 2.29. To evaluate the correct measuring time for time-critical measurements at a given standard deviation, the standard deviation of the ACP values at the output of the real DUT must be determined.

NADC Repeata bility

1.4

1.2

Standard Deviation / dB

0.8

0.6

0.4

0.2

Alt1 Channels

Tx Channel

Adj Channels

10 100 1000

Fig. 2.29 Standard deviation of the results of Fast ACP measurement as a function of

selected sweep time evaluated from 100 measurements per sweep time

Swe ep Time / m s

2.38 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

2.5.3.3 Measurement Example 3 – Measuring the Modulation Spectrum in Burst Mode with the Gated Sweep Function

Since transmission systems compliant to IS136 use a TDMA method, the adjacent channel power must also be measured in burst mode. An IS136 TDMA frame is divided into 6 time slots. Two of these slots are assigned to a subscriber. This means that the ratio of transmit time to off-time for IS136 mobile phones is only 1:3 (e.g. time slots 1 and 4)

The R&S FSU supports the measurement of the adjacent channel power in the TDMA mode with the Gated Sweep function.

Test setup with the R&S Signal Generator SMIQ:

The R&S SMIQ has to be equipped with options R&S SMIQ-B10 or R&S SMIQ-B20 (modulation coder) and R&S SMIQ-B11 (data generator).

Option R&S SMIQ-Z5 is required to trigger the R&S FSU. This option is connected to the R&S SMIQ’s parallel output port. The BNC output Trigger 1 of the R&S SMIQZ5 provides a TTL trigger signal on the rising edge of the IS136 burst, which is used to start the R&S FSU sweep in the Gated Sweep mode.

The R&S FSU’s IF power trigger is not suitable for IS136. It triggers on every level edge of the input signal. Since the modulation of the IS136 signal causes level dips even during the transmit burst, there is no way of ensuring that the R&S FSU is only triggered on the burst edge.

Settings on signal generator R&S SMIQ:

Switch the signal generator to the IS136 burst mode (time slots 1 and 4 are switched on, the other time slots are switched off).

The R&S SMIQ is set as follows to generate the signal:

➢ Press the PRESET key. ➢ Press the FREQ key and enter 850 MHz. ➢ Press the LEVEL key and enter -20 dBm. ➢ Press the RETURN key. ➢ Select DIGITAL STANDARD using the spinwheel and press the SELECT key. ➢ Select NADC using the spinwheel and press the SELECT key. ➢ Press the SELECT key. ➢ Select ON using the spinwheel and press the SELECT key.

Operating Manual 1313.9646.12 - 02 2.39

R&S FSU Getting Started

Measurements on Modulated Signals

➢ Press the RETURN key. ➢ Keep turning the spinwheel until SAVE/RECALL FRAME appears in the list and

select the menu item SAVE/RECALL FRAME using the SELECT key.

➢ The cursor is set to GET PREDEFINED FRAME. ➢ Press the SELECT key. ➢ Select UP1TCH using the spinwheel and press the SELECT key.

In the following operating sequence for the R&S FSU, it is assumed that steps 1 to 6 of the previous example (example no. 2) have already been performed.

1. Configuring the Gated Sweep function on the R&S FSU.

➢ Press the TRIG key. ➢ Press the GATED TRIGGER softkey. ➢ Press the EXTERN softkey. ➢ Press the GATE SETTINGS ! softkey.

The R&S FSU switches to time domain measurement so that the setting of the Gated Sweep parameters can be checked visually.

➢ Press the SWEEPTIME softkey and enter 10 ms.

Exactly one TDMA burst will be displayed.

➢ Press the GATE DELAY softkey and enter 2 ms or set the Gate Delay using

the spinwheel so that the burst is reliably detected.

➢ Press the GATE LENGTH softkey and enter 5 ms or set the vertical line for the

gate length using the spinwheel so that the burst is reliably detected.

Fig. 2.30 Setting the parameters Gate Delay and Gate Length in time domain. The time

interval required to measure the spectrum is indicated by two vertical lines.

➢ Press the PREV key.

The R&S FSU now performs the ACP measurement only during the switch-on phase of the TDMA burst. The measurement is stopped during the switch-off phase.

2.40 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

The selected sweep time is the net sweep time, i.e. the time during which the R&S FSU is actually measuring. The complete frame of an IS136 signal takes 40 ms. In the above example, measurement only takes place for 2x5 ms within a frame. The R&S FSU is therefore only measuring for 25% of the frame duration. The total measuring time is therefore four times that for the CW mode.

2.5.3.4 Measurement Example 4 – Measuring the Transient Spectrum in Burst Mode with the Fast ACP function

In addition to the modulation spectrum or adjacent channel power from the modulation of the RF carrier, the spectrum or adjacent channel power generated by burst edges is also to be measured in TDMA systems. The spectrum is a pulse spectrum and must be measured with the peak detector. With the usual IBW method, only the power of the continuously modulated signal can be measured properly. Even if the modulation spectrum is transmitted in the TDMA mode, the measurement of the modulation spectrum will work because the burst edges are blanked out for the measurement by means of the Gated Sweep function. The R&S FSU performs measurements only if the modulation spectrum is continuous when the burst is on.

However, the IBW method fails for the spectrum created by the burst edges. As the measurement is carried out with resolution bandwidths that are very small compared to the signal bandwidth, a spurious amplitude distribution is obtained in the defined measurement channel because of the resolution bandwidth. The small resolution bandwidth cannot settle to the peak amplitudes of the test signal. This problem is avoided in the R&S FSU by performing time domain measurements with the root raised cosine filter specified in the IS136 standard.

If the peak detector is used instead of the default RMS detector (which is selected when the standard is selected), the true adjacent channel power generated by the burst edges can also be measured.

Test setup:

The test setup for this example and the settings for R&S SMIQ are identical to those in the previous example.

Measurement with the R&S FSU:

1. Set the R&S FSU to its default state.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Synchronize the R&S FSU to an external reference frequency.

➢ Press the SETUP key. ➢ Set the REFERENCE softkey to EXT.

3. Set the center frequency to 850 MHz

➢ Press the FREQ key and enter 850 MHz.

4. Configure the adjacent channel power measurement for IS136 signals in

Fast ACP mode.

➢ Press the MEAS key.

Operating Manual 1313.9646.12 - 02 2.41

R&S FSU Getting Started

Measurements on Modulated Signals

➢ Press the CHAN PWR ACP ! softkey. ➢ Press the CP/ACP STANDARD softkey. ➢ Select NADC IS136 from the list of standards and press ENTER. ➢ Press the CP/ACP CONFIG ! softkey. ➢ Set the FAST ACP softkey to ON.

The R&S FSU performs the power measurement in 5 channels (in the useful channel and in the two upper and lower adjacent channels).

5. Set the optimum reference level and RF attenuation for the measurement.

➢ Press the ADJUST REF LEVEL softkey.

The R&S FSU sets the optimum RF attenuation and the optimum reference level on the basis of the measured channel power.

6. Select the peak detector and increase the sweep time to 10 s.

➢ Press the TRACE key. ➢ Press the DETECTOR softkey. ➢ Press the DETECTOR MAX PEAK softkey. ➢ Press the SWEEP key. ➢ Press the SWEEP TIME softkey and enter 10 s.

The R&S FSU measures the adjacent channel power generated by the burst edges and the modulation.

Fig. 2.31 Adjacent channel power due to modulation spectrum and transient spectrum#

The peak power display depends on the selected sweep time. The longer the sweep time, the higher the probability of measuring the highest peak amplitude of the signal.

With shorter sweep times, level dips can be seen in the time domain traces. These level dips come from the burst characteristics of the signal. The numerical results, however, indicate the peak amplitudes during the measurement in the corresponding channel.

2.42 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

2.5.3.5 Measurement Example 5 – Measuring adjacent channel power of a W-CDMA uplink signal

Test setup:

Settings on the signal generator (e.g. R&S SMIQ):

Frequency: 1950 MHz

Level: 4 dBm

Modulation: 3 GPP W-CDMA Reverse Link

Measurement with the R&S FSU:

1. Set the R&S FSU to its default state.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Set the center frequency to 1950 MHz.

➢ Press the FREQ key and enter 1950 MHz.

3. Switch on the ACP measurement for W-CDMA.

➢ Press the MEAS key. ➢ Press the CHAN PWR ACP ! softkey. ➢ Press the CP/ACP STANDARD softkey. ➢ From the list of standards, select W-CDMA 3GPP REV using the spinwheel or

the cursor down key below the spinwheel and press ENTER.

The R&S FSU sets the channel configuration to the 3GPP W-CDMA standard for mobiles with two adjacent channels above and below the transmit channel. The frequency span, the resolution and video bandwidth and the detector are automatically set to the correct values. The spectrum is displayed in the upper part of the screen and the channel power, the level ratios of the adjacent channel powers and the channel configuration in the lower part of the screen. The individual channels are displayed as vertical lines on the graph.

4. Set the optimum reference level and the RF attenuation for the applied

signal level.

➢ Press the ADJUST REF LEVEL softkey.

The R&S FSU sets the optimum RF attenuation and the reference level for the power in the transmission channel to obtain the maximum dynamic range. The following figure shows the result of the measurement:

Operating Manual 1313.9646.12 - 02 2.43

R&S FSU Getting Started

Measurements on Modulated Signals

Fig. 2.32 Measuring the relative adjacent channel power on a W-CDMA uplink signal

5. Measuring adjacent channel power with the Fast ACP method.

➢ Press the CP/ACP CONFIG ! softkey. ➢ Set FAST ACP softkey to ON. ➢ Press the ADJUST REF LVL softkey.

The R&S FSU measures the power of the individual channels in the time domain. A root raised cosine filter with the parameters α = 0.22 and chip rate

3.84 Mcps (= receive filter for 3GPP W-CDMA) is used as the channel filter.

Fig. 2.33 Measuring the adjacent channel power of a W-CDMA signal with the Fast ACP

method

With W-CDMA, the R&S FSU dynamic range for adjacent channel measurements is limited by the 14-bit A/D converter. The greatest dynamic range is, therefore, obtained with the IBW method.

2.44 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

Optimum Level Setting for ACP Measurements on W-CDMA Signals

The dynamic range for ACPR measurements is limited by the thermal noise floor, the phase noise and the intermodulation (spectral regrowth) of the R&S FSU. The power values produced by the R&S FSU due to these factors accumulate linearly. They depend on the applied level at the input mixer. The three factors are shown in the figure below for the adjacent channel (5 MHz carrier offset)

CLR /dBc

-50

-55

-60

-65

-70

-75

-80

-85

-90

-20 -15 -10 -5 0

Fig. 2.34 The R&S FSU’s dynamic range for adjacent channel power measurements on W-CDMA

thermal

noise

phase

noise

uplink signals is a function of the mixer level.

total

CLR

spectral

regrowth

Mixer level / dBm

The level of the W-CDMA signal at the input mixer is shown on the horizontal axis, i.e. the measured signal level minus the selected RF attenuation. The individual components which contribute to the power in the adjacent channel and the resulting relative level (total ACPR) in the adjacent channel are displayed on the vertical axis. The optimum mixer level is –10 dBm. The relative adjacent channel power (ACPR) at an optimum mixer level is –77,5 dBc. Since, at a given signal level, the mixer level is set in 5 dB steps with the 5 dB RF attenuator, the optimum 5 dB range is shown in the figure: it spreads from –13 dBm to –8 dBm. The obtainable dynamic range in this range is 76 dB.

To set the attenuation parameter manually, the following method is recommended:

• Set the RF attenuation so that the mixer level (= measured channel power – RF

attenuation) is between -13 dBm and -8 dBm.

• Set the reference level to the largest possible value where no overload (IFOVLD)

is indicated.

This method is automated with the R&S FSU’s ADJUST REF LEVEL function. Especially in remote control mode, e.g. in production environments, it is best to correctly set the attenuation parameters prior to the measurement, as the time required for automatic setting can be saved.

To measure theR&S FSU’s intrinsic dynamic range for W-CDMA adjacent channel power measurements, a filter which suppresses the adjacent channel power is required at the output of the transmitter. A SAW filter with a bandwidth of 4 MHz, for example, can be used.

Operating Manual 1313.9646.12 - 02 2.45

R&S FSU Getting Started

Measurements on Modulated Signals

2.5.4 Amplitude Distribution Measurements

If modulation types that do not have a constant envelope in the time domain are used, the transmitter has to handle peak amplitudes that are greater than the average power. This includes all modulation types that involve amplitude modulation QPSK for example. CDMA transmission modes in particular may have power peaks that are large compared to the average power.

For signals of this kind, the transmitter must provide large reserves for the peak power to prevent signal compression and thus an increase of the bit error rate at the receiver.

The peak power, or the crest factor of a signal is therefore an important transmitter design criterion. The crest factor is defined as the peak power / mean power ratio or, logarithmically, as the peak level minus the average level of the signal.

To reduce power consumption and cut costs, transmitters are not designed for the largest power that could ever occur, but for a power that has a specified probability of being exceeded (e.g. 0.01%).

To measure the amplitude distribution, the R&S FSU has simple measurement functions to determine both the APD = Amplitude Probability Distribution and CCDF = Complementary Cumulative Distribution Function.

In the literature, APD is also used for the probability of amplitude violation. This is the complimentary function to the APD function of R&S FSU. The term PDF (=Probability Density Function) which is frequently used in the literature corresponds to the APD function of R&S FSU.

In the APD display mode, the probability of occurrence of a certain level is plotted against the level.

In the CCDF display mode, the probability that the mean signal power will be exceeded is shown in percent.

2.5.4.1 Measurement Example – Measuring the APD and CCDF of white noise generated by the R&S FSU

1. Set the R&S FSU to its default state.

➢ Press the PRESET key.

The R&S FSU is in its default state.

2. Configure the R&S FSU for APD measurement

➢ Press the AMPT key and enter -60 dBm.

The R&S FSU’s intrinsic noise is displayed at the top of the screen.

➢ Press the MEAS key. ➢ Press the SIGNAL STATISTIC ! softkey. ➢ Set the APD softkey to ON.

The R&S FSU sets the frequency span to 0 Hz and measures the amplitude probability distribution (APD). The number of uncorrelated level measurements used for the measurement is 100000. The mean power and the peak power are displayed in dBm. The crest factor (peak power – mean power) is output as well (see Fig. 2.35).

2.46 Operating Manual 1313.9646.12 - 02

R&S FSU Getting Started

Measurements on Modulated Signals

Fig. 2.35 Amplitude probability distribution of white noise

3. Switch to the CCDF display mode.

➢ Set the CCDF softkey to ON

The APD measurement is switched off and the CCDF display mode is switched on.

Fig. 2.36 The CCDF of white noise

The CCDF trace indicates the probability that a level will exceed the mean power. The level above the mean power is plotted along the X axis of the graph. The origin of the axis corresponds to the mean power level. The probability that a level will be exceeded is plotted along the Y axis.

4. Bandwidth selection

If the amplitude distribution is measured, the resolution bandwidth must be set in a way that the complete spectrum of the signal to be measured falls within the bandwidth. This is the only way of ensuring that all the amplitudes will pass through the IF filter without being distorted. If the selected resolution bandwidth is too small for a digitally modulated signal, the amplitude distribution at the output of the IF filter becomes a Gaussian distribution according to the central limit theorem and so corresponds to a white noise signal. The true amplitude distribution of the signal therefore cannot be determined.

Operating Manual 1313.9646.12 - 02 2.47

R&S FSU Getting Started

Measurements on Modulated Signals

A video bandwidth which is large in comparison to the resolution bandwidth (≥ 3 x RBW) must be selected. This ensures that the amplitude peaks of the signal are not smoothed by the lowpass effect of the video filter. The video bandwidth is set automatically during statistics measurements.

Since the video bandwidth of the R&S FSU is limited to 10 MHz, lowpass filtering occurs during measurements with a resolution bandwidth of 10 MHz. Additional band-limiting occurs at a resolution bandwidth of 10 MHz due to the lowpass filtering at the output of the log amplifier. The latter limits the video signal to a bandwidth of 8 MHz in order to obtain sufficient suppression of the 20.4 MHz IF. The level range of the signal amplitudes, e.g. during APD white-noise measurements, is smaller. For broadband-modulated signals such as W-CDMA signals, the effect depends on the bandwidth occupied by the signal. At a signal bandwidth of 4 MHz, the amplitude distribution can be measured correctly with the effective video bandwidth.

5. Selecting the number of samples

For statistics measurements with the R&S FSU, the number of samples N

Samples

is entered for statistical evaluation instead of the sweep time. Since only statistically independent samples contribute to statistics, the measurement or sweep time is calculated automatically. It is indicated on the R&S FSU display. The samples are statistically independent if the time difference is at least 1/RBW. The sweep time SWT is, therefore, expressed as follows:

SWT = N

Samples

/RBW

2.48 Operating Manual 1313.9646.12 - 02

R&S FSU Manual Operation

3 Manual Operation

For details refer to the Quick Start Guide chapter 4, “Basic Operation”.

Operating Manual 1313.9646.12 - 02 3.1

R&S FSU Instrument Functions

4 Instrument Functions

4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4

4.2 R&S FSU Initial Configuration – PRESET Key . . . . . . . . . . . . . . . . . . . . . . 4.5

4.3 Mode Selection – Hotkey Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7

4.4 Return to Manual Operation – LOCAL Menu . . . . . . . . . . . . . . . . . . . . . . . 4.8

4.5 Analyzer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9

4.5.1 Frequency and Span Selection – FREQ Key . . . . . . . . . . . . . . . . . . . . 4.10

4.5.2 Setting the Frequency Span – SPAN Key . . . . . . . . . . . . . . . . . . . . . . . 4.14

4.5.3 Level Display Setting and RF Input Configuration – AMPT Key . . . . . . 4.16

4.5.3.1 Electronic Attenuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.19

4.5.4 Setting the Bandwidths and Sweep Time – BW Key . . . . . . . . . . . . . . . 4.21

4.5.4.1 Filter Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.26

4.5.5 Sweep Settings – SWEEP Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.31

4.5.6 Triggering the Sweep – TRIG Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.34

4.5.7 Selection and Setting of Traces – TRACE Key . . . . . . . . . . . . . . . . . . . 4.41

4.5.7.1 Selection of Trace Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.41

4.5.7.2 Selection of Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.49

4.5.7.3 Mathematical Functions for Traces . . . . . . . . . . . . . . . . . . . . . . . . 4.53

4.5.8 Recording the Correction Data – CAL Key . . . . . . . . . . . . . . . . . . . . . . 4.55

4.5.9 Markers and Delta Markers – MKR Key . . . . . . . . . . . . . . . . . . . . . . . . 4.58

4.5.9.1 Frequency Measurement with the Frequency Counter . . . . . . . . . 4.60

4.5.10 Marker Functions – MKR FCTN Key . . . . . . . . . . . . . . . . . . . . . . . . . . 4.65

4.5.10.1 Activating the Markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.66

4.5.10.2 Measurement of Noise Density . . . . . . . . . . . . . . . . . . . . . . . . . . 4.66

4.5.10.3 Phase Noise Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.68

4.5.10.4 Measurement of the Filter or Signal Bandwidth . . . . . . . . . . . . . 4.70

4.5.10.5 Measurement of a Peak List . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.71

4.5.10.6 AF Demodulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.74

4.5.10.7 Selecting the Trace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.76

4.5.11 Change of Settings via Markers – MKR-> Key . . . . . . . . . . . . . . . . . . 4.77

4.1 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

4.5.12 Power Measurements – MEAS Key . . . . . . . . . . . . . . . . . . . . . . . . . . 4.84

4.5.12.1 Power Measurement in Time Domain . . . . . . . . . . . . . . . . . . . . . 4.85

4.5.12.2 Channel and Adjacent-Channel Power Measurements . . . . . . . 4.90

4.5.12.3 Measurement of Occupied Bandwidth . . . . . . . . . . . . . . . . . . . 4.111

4.5.12.4 Measurement of Signal Amplitude Statistics . . . . . . . . . . . . . . . 4.113

4.5.12.5 Measurement of Carrier/Noise Ratio C/N and C/No . . . . . . . . . 4.122

4.5.12.6 Measurement of the AM Modulation Depth . . . . . . . . . . . . . . . . 4.124

4.5.12.7 Measurement of the Third Order Intercept (TOI) . . . . . . . . . . . . 4.125

4.5.12.8 Harmonic Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.128

4.5.12.9 Measuring Spurious Emissions . . . . . . . . . . . . . . . . . . . . . . . . . 4.130

4.5.12.10 Spectrum Emission Mask Measurement . . . . . . . . . . . . . . . . . 4.137

4.6 Basic Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.156

4.6.1 Setup of Limit Lines and Display Lines – LINES Key . . . . . . . . . . . . . 4.156

4.6.1.1 Selection of Limit Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.157

4.6.1.2 Entry and Editing of Limit Lines . . . . . . . . . . . . . . . . . . . . . . . . . . 4.160

4.6.1.3 Display Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.165

4.6.2 Configuration of Screen Display – DISP Key . . . . . . . . . . . . . . . . . . . 4.168

4.6.3 Instrument Setup and Interface Configuration – SETUP Key . . . . . . . 4.174

4.6.3.1 External Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.177

4.6.3.2 External Noise Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.178

4.6.3.3 RF Preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.178

4.6.3.4 Transducer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.178

4.6.3.5 Programming the Interface Configuration and Time Setup . . . . . 4.184

4.6.3.6 System Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.199

4.6.3.7 Service Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.201

4.6.3.8 Firmware Update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.205

4.6.4 Saving and Recalling Data Sets – FILE Key . . . . . . . . . . . . . . . . . . . . 4.207

4.6.4.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.207

4.6.4.2 Operating Concept of File Managers . . . . . . . . . . . . . . . . . . . . . 4.212

4.6.5 Measurement Documentation – HCOPY Key . . . . . . . . . . . . . . . . . . . 4.217

4.6.5.1 Selecting Printer Colors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.220

4.7 Tracking Generator – Option R&S FSU-B9 . . . . . . . . . . . . . . . . . . . . . . . 4.224

4.7.1 Tracking Generator Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.225

4.7.2 Transmission Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.227

4.7.2.1 Calibration of Transmission Measurement . . . . . . . . . . . . . . . . . 4.227

4.7.2.2 Normalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.229

4.7.3 Reflection Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.233

4.7.3.1 Calibration of Reflection Measurement . . . . . . . . . . . . . . . . . . . . 4.233

4.7.4 Calibration Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.234

4.7.5 Frequency-Converting Measurements . . . . . . . . . . . . . . . . . . . . . . . . 4.236

4.7.6 External Modulation of the Tracking Generator . . . . . . . . . . . . . . . . . . 4.237

4.7.7 Power Offset of the Tracking Generator . . . . . . . . . . . . . . . . . . . . . . . 4.239

Operating Manual 1313.9646.12 - 02 4.2

R&S FSU Instrument Functions

4.8 External Generator Control – Option R&S FSP-B10 . . . . . . . . . . . . . . . 4.240

4.8.1 External Generator Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.241

4.8.2 Transmission Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.242

4.8.2.1 Calibration of Transmission Measurement . . . . . . . . . . . . . . . . . 4.242

4.8.2.2 Normalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.244

4.8.3 Reflection Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.248

4.8.3.1 Calibration of Reflection Measurement . . . . . . . . . . . . . . . . . . . . 4.248

4.8.4 Calibration Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.249

4.8.5 Frequency-Converting Measurements . . . . . . . . . . . . . . . . . . . . . . . . 4.250

4.8.6 Configuration of an External Generator . . . . . . . . . . . . . . . . . . . . . . . . 4.251

4.8.7 List of Generator Types Supported by the R&S FSU . . . . . . . . . . . . . 4.254

4.9 LAN Interface - Option R&S FSP-B16 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.258

4.9.1 NOVELL Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.258

4.9.2 MICROSOFT Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.258

4.9.3 Remote Data Transfer with TCP/IP Services . . . . . . . . . . . . . . . . . . . 4.258

4.10 RSIB Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.260

4.10.1 Remote Control via RSIB Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 4.260

4.10.1.1 Windows Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.260

4.10.1.2 UNIX Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.261

4.11 RSIB Interface Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.262

4.11.1 Overview of Interface Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.262

4.11.1.1 Variables ibsta, iberr, ibcntl . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.263

4.11.1.2 Description of Interface Functions . . . . . . . . . . . . . . . . . . . . . . . 4.264

4.11.2 Programming via the RSIB Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 4.273

4.11.2.1 Visual Basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.273

4.11.2.2 Visual Basic for Applications (Winword and Excel) . . . . . . . . . . 4.277

4.11.2.3 C / C++ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.278

4.12 LO/IF ports for external mixers - Option R&S FSU-B21 . . . . . . . . . . . . 4.280

4.12.1 Connecting an External Mixer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.280

4.12.2 Manual Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.282

4.12.3 Conversion Loss Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.288

4.12.3.1 Editing a Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.291

4.12.4 Signal Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.295

4.12.4.1 Remarks Concerning Signal Identification with AUTO ID . . . . . 4.296

4.12.5 Introductory Example of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4.302

4.13 Broadband FM Demodulator - Option R&S FSU-B27 . . . . . . . . . . . . . . 4.306

4.13.1 Settings of the FM demodulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.307

4.14 Trigger Port – Option R&S FSP-B28 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.309

4.3 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Introduction

4.1 Introduction

All functions of the R&S FSU and their application are explained in detail in this chapter. The sequence of the described menu groups depends on the procedure selected for the configuration and start of a measurement:

1. Resetting the instrument

– “R&S FSU Initial Configuration – PRESET Key” on page 4.5

2. Setting the mode

– “Mode Selection – Hotkey Bar” on page 4.7

– “Return to Manual Operation – LOCAL Menu” on page 4.8

3. Setting the measurement parameters in analyzer mode

– “Analyzer Mode” on page 4.9

4. Basic functions for general settings, printout and data management

– “Setup of Limit Lines and Display Lines – LINES Key” on page 4.156

– “Configuration of Screen Display – DISP Key” on page 4.168

– “Instrument Setup and Interface Configuration – SETUP Key” on page 4.174

– “Saving and Recalling Data Sets – FILE Key” on page 4.207

– “Measurement Documentation – HCOPY Key” on page 4.217

5. Additional and optional functions

– “Tracking Generator – Option R&S FSU-B9” on page 4.224

– “External Generator Control – Option R&S FSP-B10” on page 4.240

– “LAN Interface - Option R&S FSP-B16” on page 4.258

– “LO/IF ports for external mixers - Option R&S FSU-B21” on page 4.280

– “Broadband FM Demodulator - Option R&S FSU-B27” on page 4.306

– “Trigger Port – Option R&S FSP-B28” on page 4.309

The operating concept is described in the Quick Start Guide, chapter 4, “Basic Operation”.

The remote commands (if any) are indicated for each softkey. A detailed description of the associated remote commands is given in chapter “Remote Control – Descrip-

tion of Commands”.

Operating Manual 1313.9646.12 - 02 4.4

R&S FSU Instrument Functions

R&S FSU Initial Configuration – PRESET Key

4.2 R&S FSU Initial Configuration – PRESET Key

PRESET

Using the PRESET key, the R&S FSU can be set to a predefined initial state.

The settings are selected in a way that the RF input is always protected against overload, provided that the applied signal levels are in the allowed range for the instrument.

The initial instrument state set by the PRESET key can be adapted to arbitrary applications using the STARTUP RECALL function. With this function the STARTUP RECALL data set is loaded upon pressing the PRESET key. For further information refer to section “Saving and Recalling Data Sets – FILE Key” on

page 4.207.

Pressing the PRESET key causes the R&S FSU to enter its initial state according to the following table:

4.5 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

R&S FSU Initial Configuration – PRESET Key

Table 4-1 Initial State of R&S FSU

Parameter Settings

Mode Spectrum

Center frequency 0,1× center frequency

Center frequency step size 0.1 * center frequency

Span model-dependant, see data sheet

RF attenuation auto (5 dB)

Reference level -20 dBm

Level range 100 dB log

Level unit dBm

Sweep time auto

Resolution bandwidth auto (3 MHz)

Video bandwidth auto (10 MHz)

FFT filters off

Span / RBW 50

RBW / VBW 0,33

Sweep cont

Trigger free run

Trace 1 clr write

Trace 2/3 blank

Detector auto peak

Trace math off

Frequency offset 0 Hz

Reference level offset 0 dB

Reference level position 100 %

Grid abs

Cal correction on

Noise source off

Input RF

Display Full screen, active screen A

Operating Manual 1313.9646.12 - 02 4.6

R&S FSU Instrument Functions

Mode Selection – Hotkey Bar

4.3 Mode Selection – Hotkey Bar

For fast mode selection the R&S FSU has keys located under the measurement screen, the so-called hotkeys. These hotkeys are displayed depending on the options installed on the instrument. According to the selected mode, the corresponding softkey menus are displayed (on the right side of the measurement screen).

In this section, only the hotkeys provided by the basic model are described. For information on the other hotkeys refer to the corresponding option descriptions.

Fig. 4.15 Hotkey bar of the basic model

SPECTRUM

SCREEN A / SCREEN B

The SPECTRUM hotkey sets R&S FSU to analyzer mode. For details on the softkey menus refer to section “Analyzer Mode” on page 4.9.

The analyzer mode is the default mode of R&S FSU.

Remote command: INST:SEL SAN

INST:NSEL 1

The MORE hotkey switches to side hotkey bar(s) and back to the main hotkey bar. In the side hotkey bar(s), the hotkeys for the options are located. For further information refer to the descriptions of the corresponding options.

With the SCREEN A / SCREEN B hotkey two different settings can be selected on the R&S FSU in the FULL SCREEN display mode.

In the SPLIT SCREEN display mode the key switches between active diagram A and B.

The key designation indicates the diagram which has been activated by means of the key.

The currently active window is marked by or on the right of the diagram.

Remote command: DISP:WIND<1|2>:SEL

4.7 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Return to Manual Operation – LOCAL Menu

4.4 Return to Manual Operation – LOCAL Menu

LOCAL

The LOCAL menu is displayed on switching the instrument to remote control mode.

At the same time, the hotkey bar is blanked out and all keys are disabled except the PRESET key.

The LOCAL softkey and the DISPLAY UPDATE ON/OFF softkey are displayed.

Depending on the setting of the DISPLAY UPDATE ON/OFF softkey, the diagrams, traces and diplay fields are displayed or hidden. For further details on the DISPLAY UPDATE ON/OFF softkey refer to Instrument Setup and Interface Configuration –

SETUP Key.

The LOCAL key switches the instrument from remote to manual operation, with the assumption that the remote controller has not previously set the LOCAL LOCKOUT function.

A change in the control mode consists of:

• Enabling the Front Panel Keys

Returning to manual operation enables all inactive keys and turns on the hotkey bar. The softkey menu which is displayed is the main menu of the current mode.

• Inserting the measurement diagrams

The blanked diagrams, traces and display fields are inserted.

• Generating the message OPERATION COMPLETE

If, at the time of pressing the LOCAL softkey, the synchronization mechanism via *OPC, *OPC? or *WAI is active, the currently running measurement procedure is aborted and synchronization is achieved by setting the corresponding bits in the registers of the status reporting system.

• Setting Bit 6 (User Request) of the Event Status Register

With a corresponding configuration of the status reporting system, this bit immediately causes the generation of a service request (SRQ) which is used to inform the control software that the user wishes to return to front-panel control. This information can be used, e.g., to interrupt the control program so that the user can make necessary manual corrections to instrument settings. This bit is set each time the LOCAL softkey is pressed.

If the LOCAL LOCKOUT function is active in the remote control mode, the frontpanel PRESET key is also disabled. The LOCAL LOCKOUT state is left as soon as the process controller de-activates the REN line or the GPIB cable is disconnected from the instrument.

Operating Manual 1313.9646.12 - 02 4.8

R&S FSU Instrument Functions

Analyzer Mode

4.5 Analyzer Mode

The analyzer mode is activated by pressing the SPECTRUM hotkey (see also section “Mode Selection – Hotkey Bar” on page 4.7)

SPECTRUM

The SPECTRUM hotkey selects the mode for spectrum analysis, the so-called analyzer mode.

This mode is the default mode of the R&S FSU.

The functions provided correspond to those of a conventional spectrum analyzer. The R&S FSU measures the frequency spectrum of the test signal over the selected frequency range with the selected resolution and sweep time, or, for a fixed frequency, displays the waveform of the video signal.

If two displays (screen A and screen B) are opened after switch-on of signal analysis, the analyzer mode is only set for the display activated for entry (marked at the top right corner of diagram). For the other display, the previous settings remain valid.

Data acquisition and display of measured values is sequential: first in the upper and then in the lower display.

4.9 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

4.5.1 Frequency and Span Selection – FREQ Key

The FREQ key is used to specify the frequency axis of the active display window. The frequency axis can be defined either by the start and stop frequency or by the center frequency and bwthe span (SPAN key). With two windows (SPLIT SCREEN) displayed at the same time, the input data always refer to the window selected in the SYSTEM - DISPLAY menu.

The softkeys in the CF STEPSIZE menu depend on the selected domain: frequency domain or time domain.

FREQ

CENTER

CF STEPSIZE ! 0.1 * SPAN / 0.1 * RBW

0.5 * SPAN / 0.5 * RBW

X * SPAN / X * RBW

= CENTER

= MARKER

MANUAL

START

STOP

FREQUENCY OFFSET

SIGNAL TRACK

EXTERNAL MIXER

(option B21)

! TRACK (ON OFF)

TRACK BW

TRACK THRESHOLD

SELECT TRACE

CENTER

The CENTER softkey opens the window for manually entering the center frequency.

The allowed range of values for the center frequency is:

• for the frequency domain (span >0):

minspan / 2 ≤ f

center

≤ f

max

– minspan / 2

• and for the time domain (span = 0):

0 Hz ≤ f

center frequency

center

minspan smallest selectable span > 0 Hz (10 Hz)

max. frequency

max

center

≤ f

max

Remote command: FREQ:CENT 100MHz

CF STEPSIZE

The CF STEPSIZE softkey opens a submenu for setting the step size of the center frequency. The step size can be coupled to the span (frequency domain) or the resolution bandwidth (time domain) or it can be manually set to a fixed value. The softkeys are mutually exclusive selection keys.

The softkeys are presented according to the selected domain (frequency or time).

Operating Manual 1313.9646.12 - 02 4.10

R&S FSU Instrument Functions

Analyzer Mode

Softkeys in frequency domain:

0.1 * SPAN The 0.1 * SPAN softkey sets the step size for the center frequency entry to 10% of the span.

Remote command: FREQ:CENT:STEP:LINK SPAN

FREQ:CENT:STEP:LINK:FACT 10PCT

0.5 * SPAN The 0.5 * SPAN softkey sets the step size for the center frequency entry to 50% of the span.

Remote command: FREQ:CENT:STEP:LINK SPAN

FREQ:CENT:STEP:LINK:FACT 50PCT

X * SPAN The X * SPAN softkey allows the factor defining the center frequency step size to be

entered as % of the span.

Remote command: FREQ:CENT:STEP:LINK SPAN

FREQ:CENT:STEP:LINK:FACT 20PCT

= CENTER The = CENTER softkey sets the step size coupling to MANUAL and the step size to

the value of the center frequency. This function is especially useful during measurements of the signal harmonic content because by entering the center frequency each stroke of the STEP key selects the center frequency of another harmonic.

Remote command: --

= MARKER The = MARKER softkey sets the step size coupling to MANUAL and the step size to

the value of the marker. This function is especially useful during measurements of the signal harmonic content at the marker position because by entering the center frequency each stroke of the STEP key selects the center frequency of another harmonic.

Remote command: --

MANUAL The MANUAL softkey activates the window for entering a fixed step size.

Remote command: FREQ:CENT:STEP 120MHz

Softkeys in time domain:

0.1 * RBW The 0.1 * RBW softkey sets the step size for the center frequency entry to 10% of the resolution bandwidth.

AUTO 0.1 * RBW corresponds to the default setting.

Remote command: FREQ:CENT:STEP:LINK RBW

FREQ:CENT:STEP:LINK:FACT 10PCT

0.5 * RBW The 0.5 * RBW softkey sets the step size for the center frequency entry to 50% of the resolution bandwidth.

Remote command: FREQ:CENT:STEP:LINK RBW

FREQ:CENT:STEP:LINK:FACT 50PCT

4.11 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

X * RBW The X * RBW softkey allows the factor defining the center frequency step size to be

entered as % of the resolution bandwidth.

Values between 1 % and 100 % in steps of 1 % are allowed. The default setting is 10 %.

Remote command: FREQ:CENT:STEP:LINK RBW

FREQ:CENT:STEP:LINK:FACT 20PCT

= CENTER The = CENTER softkey sets the step size coupling to MANUAL and the step size to

Remote command: --

= MARKER The = MARKER softkey sets the step size coupling to MANUAL and the step size to

START

STOP

Remote command: --

MANUAL The MANUAL softkey activates the window for entering a fixed step size.

Remote command: FREQ:CENT:STEP 120MHz

The START softkey activates the window for manually entering the start frequency.

The allowed range of values for the start frequency is: 0 Hz ≤ f

start frequency

start

minspan smallest selectable span (10 Hz)

max. frequency

max

start

≤ f

- minspan

max

Available for measurements in the frequency domain.

Remote command: FREQ:STAR 20MHz

The STOP softkey activates the window for entering the stop frequency.

The allowed range of values for the stop frequency is: minspan ≤ f

stop frequency

stop

minspan smallest selectable span (10 Hz)

max. frequency

max

stop

≤ f

max

Available for measurements in the frequency domain.

Remote command: FREQ:STOP 2000MHz

Operating Manual 1313.9646.12 - 02 4.12

R&S FSU Instrument Functions

Analyzer Mode

FREQUENCY OFFSET

SIGNAL TRACK

The FREQUENCY OFFSET softkey activates the window for entering an arithmetical frequency offset which is added to the frequency axis labelling. The allowed range of values for the offset is -100 GHz to 100 GHz. The default setting is 0 Hz.

Remote command: FREQ:OFFS 10 MHz

The SIGNAL TRACK softkey switches on the tracking of a signal near the center frequency. The signal is tracked as long it is in the search bandwidth around the center frequency defined with TRACK BW and above the level threshold defined with TRACK THRESHOLD.

For that purpose, the maximum signal is determined (PEAK SEARCH) on the screen and the center frequency is set to this signal (MARKER ->CENTER) after each frequency sweep within the search bandwidth.

If the signal falls below the level threshold or jumps out of the search bandwidth around the center frequency, the center frequency is not varied until a signal is in the search bandwidth above the level threshold. This can be achieved by manually modifying the center frequency, for example.

On switching on, the softkey is highlighted and the search bandwidth and the threshold value are marked on the diagram by two vertical lines and one horizontal line. All these lines are provided with the designation TRK.

At the same time a submenu is opened in which the search bandwidth, the threshold value and the trace can be modified for the maximum search.

The softkey is only available in the frequency domain (span >0).

Remote command: CALC:MARK:FUNC:STR OFF

TRACK (ON

OFF)

TRACK BW The TRACK BW softkey defines the bandwidth around the center frequency within

TRACK

THRESHOLD

SELECT TRACE The SELECT TRACE softkey selects the trace on which signal tracking is to be per-

The TRACK (ON OFF) softkey switches on and off signal tracking.

Remote command: CALC:MARK:FUNC:STR OFF

which the largest signal is searched. The frequency range is symmetrical with respect to the center frequency.

Remote command: CALC:MARK:FUNC:STR:BAND 10KHZ

The TRACK THRESHOLD softkey defines the threshold value for signal detection. The value is always entered as an absolute level value.

Remote command: CALC:MARK:FUNC:STR:THR -70DBM

formed.

Remote command: CALC:MARK:FUNC:STR:TRAC 1

4.13 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

4.5.2 Setting the Frequency Span – SPAN Key

The SPAN key opens a menu which offers various options for setting the span.

The entry of the span (SPAN MANUAL softkey) is automatically active for span > 0 Hz.

For span = 0 Hz the entry for sweep time (SWEEPTIME MANUAL) is automatically active.

With two windows (SPLIT SCREEN) displayed at the same time, the input data always refer to the window selected with the SCREEN A/B hotkey.

SPAN

SPAN MANUAL

SWEEPTIME MANUAL

SPAN MANUAL

SWEEPTIME MANUAL

FULL SPAN

ZERO SPAN

LAST SPAN

FREQ AXIS (LIN LOG)

The SPAN MANUAL softkey activates the window for manually entering the frequency span. The center frequency is kept constant.

Allowed range of span values:

• for the time domain (span = 0): 0 Hz

• and for the frequency domain (span >0): minspan ≤ f

frequency span

span

minspan smallest selectable span (10 Hz)

max. frequency

max

span

≤ f

max

Remote command: FREQ:SPAN 2GHz

The SWEEPTIME MANUAL softkey activates the window for entering the sweep time manually with Span = 0 Hz.

Remote command: SWE:TIME 10s

FULL SPAN

The FULL SPAN softkey sets the span to the full frequency range of R&S FSU.

Remote command: FREQ:SPAN:FULL

ZERO SPAN

The ZERO SPAN softkey sets the span to 0 Hz. The x-axis becomes the time axis with the grid lines corresponding to 1/10 of the current sweep time (SWT).

Remote command: FREQ:SPAN 0Hz

LAST SPAN

After changing the span setting the LAST SPAN softkey activates the previous set- ting. With this function a fast change between overview measurement (FULL SPAN) and detailed measurement (manually set center frequency and span) is possible.

Operating Manual 1313.9646.12 - 02 4.14

R&S FSU Instrument Functions

Analyzer Mode

Only values > 0 Hz are restored, i.e. a transition between time and frequency domain is not possible.

Remote command: --

FREQ AXIS (LIN LOG)

The FREQ AXIS (LIN LOG) softkey switches between linear and logarithmic scaling of the frequency axis. Switch over is only possible if the stop/start frequency ratio is ≥1.4.

The default state is LIN.

The logarithmic frequency axis is only available in analyzer mode and it is not available in zero span mode, in external mixer mode, with frequency offset or if the ratio stop frequency / start frequency is below 1.4.

Remote command: DISP:WIND<1|2>:TRAC:X:SPAC LIN

4.15 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

4.5.3 Level Display Setting and RF Input Configuration – AMPT Key

The AMPT key is used to set the reference level, the maximum level and the display range of the active window as well as the input impedance and the input attenuation of the RF input.

The AMPT key opens a menu for setting the reference level and the input attenuation of the active window. The data entry for the reference level (REF LEVEL softkey) is opened automatically.

Further settings regarding level display and attenuation can be made in this menu.

AMPT

REF LEVEL

RANGE LOG 100 dB

RANGE LOG MANUAL

RANGE LINEAR

UNIT

! dBm / dBmV / dBµV/

RF INPUT (AC DC)

RF ATTEN MANUAL

RF ATTEN AUTO

NOISE CORR (ON OFF)

Side menu

REF LEVEL POSITION

REF LEVEL OFFSET

GRID (ABS REL)

EL ATTEN AUTO (option B25)

! RANGE LINEAR %

RANGE LINEAR dB

dBµΑ / dBµW / VOLT / AMPERE / WATT

EL ATTEN MANUAL (option B25)

EL ATTEN OFF (option B25)

RF INPUT (50W 75W)

MIXER

! MIXER LVL AUTO

MIXER LVL MANUAL

REF LEVEL

The REF LEVEL softkey allows the reference level to be input in the currently active unit (dBm, dBµV, etc.)

Remote command: DISP:WIND:TRAC:Y:RLEV -60dBm

RANGE LOG

The RANGE LOG 100 dB softkey sets the level display range to 100 dB.

100 dB

Remote command: DISP:WIND:TRAC:Y:SPAC LOG

DISP:WIND:TRAC:Y 100DB

Operating Manual 1313.9646.12 - 02 4.16

R&S FSU Instrument Functions

Analyzer Mode

RANGE LOG MANUAL

RANGE LINEAR

RANGE

LINEAR %

RANGE

LINEAR dB

The RANGE LOG MANUAL softkey activates the manual entry of the level display range. Display ranges from 1 to 200 dB are available. Inputs which are not allowed are rounded to the next valid value.

The default setting is 100 dB.

Remote command: DISP:WIND:TRAC:Y:SPAC LOG

DISP:WIND:TRAC:Y 120DB

The RANGE LINEAR softkey selects linear scaling for the level display range of the R&S FSU. In addition, it opens a submenu for selecting % or dB for the scaling.

When linear scaling is selected, the % scaling is first activated (see also RANGE LINEAR dB softkey).

Remote command: DISP:WIND:TRAC:Y:SPAC LIN

The RANGE LINEAR % softkey selects linear scaling in % for the level display range, i.e. the horizontal lines are labelled in %. The grid is divided in decadic steps. Markers are displayed in the selected unit; delta markers are displayed in % referenced to the voltage value at the position of marker 1.

Remote command: DISP:WIND:TRAC:Y:SPAC LIN

The RANGE LINEAR dB softkey selects linear scaling in dB for the level display range, i.e. the horizontal lines are labelled in dB.

UNIT

Markers are displayed in the selected unit; delta markers are displayed in dB referenced to the power value at the position of marker 1.

Remote command: DISP:WIND:TRAC:Y:SPAC LDB

dBm

dBmV

dBµV

dBµΑ

dBµW

VOLT

AMPERE

WATT

The UNIT softkey opens a submenu to select the unit for the level axis.

The default setting is dBm.

In general, the R&S FSU measures the signal voltage at the RF input. The level display is calibrated in rms values of an unmodulated sinewave signal. In the default state, the level is displayed at a power of 1 mW (= dBm). Via the known input resistance of 50 Ω or 75 Ω, conversion to other units is possible. The units dBm, dBmV, dBµV, dBµA, dBpW, V, A and W are directly convertible.

Remote command: CALC:UNIT:POW DBM

4.17 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

RF INPUT (AC DC)

RF ATTEN MANUAL

The RF INPUT (AC DC) softkey toggles the RF input of the R&S FSU between AC and DC coupling.

The softkey is only available for models 3, 8 and 26.

Remote command: INP:COUP AC

The RF ATTEN MANUAL softkey allows the attenuation to be entered irrespective of the reference level.

The attenuation can be set in 5 dB steps between 0 and 75 dB.

Other entries will be rounded to the next higher integer value.

If the defined reference level cannot be set for the given RF attenuation, the reference level will be adjusted accordingly and the warning "Limit reached" will be output.

The 0 dB value can be entered only via the numeric keypad in order to protect the input mixer against accidental overload.

RF ATTEN AUTO

NOISE CORR (ON OFF)

Remote command: INP:ATT 40 DB

The RF ATTEN AUTO softkey sets the RF attenuation automatically as a function of the selected reference level.

This ensures that the optimum RF attenuation desired by the user is always used.

RF ATTEN AUTO is the default setting.

Remote command: INP:ATT:AUTO ON

If active, the R&S FSU corrects the results by its inherent noise. Noise correction increases the dynamic range.

After you activate noise correction, the R&S FSU performs a reference measurement of its inherent noise. In the actual measurement, the R&S FSU then substracts the noise power from the power in the channel that is measured.

The inherent noise depends on the center frequency, resolution bandwidth and level setting. Therefore, the R&S FSU deactivates noise correction if you change one these parameters. The R&S FSU shows a message that noise correction is inactive.

The R&S FSU also deactivates noise correction after you select another measurement (e.g. channel power, spectrum emission mask etc.).

After the R&S FSU deactivates noise correction, you have to activate it again manually. The R&S FSU performs a new reference measurement.

Remote command: POW:NCOR ON

Operating Manual 1313.9646.12 - 02 4.18

R&S FSU Instrument Functions

Analyzer Mode

REF LEVEL POSITION

REF LEVEL OFFSET

GRID (ABS REL)

The REF LEVEL POSITION softkey allows the reference level position to be entered.

The setting range is from -200 to +200%, 0% corresponding to the lower and 100% to the upper limit of the diagram.

Remote command: DISP:WIND:TRAC:Y:RPOS 100PCT

The REF LEVEL OFFSET softkey allows the arithmetic level offset to be entered. This offset is added to the measured level irrespective of the selected unit. The scaling of the y-axis is changed accordingly.

The setting range is ±200 dB in 0.1 dB steps.

Remote command: DISP:WIND:TRAC:RLEV:OFFS -10dB

Remote command:

The GRID (ABS REL) softkey switches between absolute and relative scaling of the level axis.

GRID ABS is the default setting.

ABS The labelling of the level lines refers to the absolute value of the reference

level.

REL The upper line of the grid is always at 0 dB.

The scaling is in dB whereas the reference level is always in the set unit (dBm, dBmV,..).

4.5.3.1 Electronic Attenuator

EL ATTEN MANUAL

For setting RANGE LINEAR (linear scaling, labelling of axes in %) the softkey is not displayed since the unit % itself implies a relative scale.

Remote command: DISP:WIND:TRAC:Y:MODE ABS

Besides the mechanical attenuator at the RF input, the R&S FSU also offers an electronic attenuation setting (option ELECTRONIC ATTENUATOR R&S FSU-B25). The attenuation range is 0 to 30 dB, with the default attenuation being preset by the mechanical attenuator.

The EL ATTEN MANUAL softkey switches the electronic attenuator on and allows the attenuation of the electronic attenuator to be set.

The attenuation can be varied in 5 dB steps from 0 to 30 dB. Other entries are rounded to the next lower integer value.

If the defined reference level cannot be set for the given RF attenuation, the reference level will be adjusted accordingly and the warning "Limit reached" will be output.

Remote command: INP:EATT:AUTO OFF

INP:EATT 10 DB

This function is only available with option ELECTRONIC ATTENUATOR B25.

4.19 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

EL ATTEN AUTO

EL ATTEN OFF

RF INPUT

Ω 75Ω)

(50

The EL ATTEN AUTO softkey switches the electronic attenuator on and automati- cally sets its attenuation to 0 dB.

The allowed setting range of the reference level ranges from the current reference level on switching on the electronic attenuator to over 30 dB. If a reference level is set outside the allowed 30-dB range, setting is performed by means of the mechanical attenuator. From this new reference level to over 30 dB the setting is again performed with the electronic attenuator.

Remote command: INP:EATT:AUTO ON

This function is only available with option ELECTRONIC ATTENUATOR B25.

The EL ATTEN OFF softkey switches the electronic attenuator off.

Remote command: INP:EATT:STAT OFF

This function is only available with option ELECTRONIC ATTENUATOR B25.

The RF INPUT (50 Ω 75 Ω) softkey switches the input impedance of the instrument between 50 Ω (= default setting) and 75 Ω.

The setting 75 Ω should be used if the input impedance (50 Ω) is transformed to 75 Ω using the corresponding adapter unit of type RAZ (= 25 Ω in series to the input impedance of the R&S FSU). The correction value used for the adoption is 1.76 dB = 10 log (75Ω / 50Ω).

MIXER

MIXER LVL

AUTO

MANUAL

All levels specified in this operating manual refer to the default setting of the instrument (50 Ω).

Remote command: INP:IMP 50OHM

The MIXER softkey opens a submenu for defining the maximum mixer level attainable for the selected reference level.

The MIXER LVL AUTO softkey activates the automatic calculation of the mixer level dependent on the selected reference level and the selected RF attenuation.

Remote command: INP:MIX:AUTO ON

The MIXER LVL MANUAL softkey allows the maximum mixer level attainable at the reference level to be entered.

The available range is 0 to -100 dBm in 10 dB steps.

Remote command: INP:MIX -25DBM

Operating Manual 1313.9646.12 - 02 4.20

R&S FSU Instrument Functions

Analyzer Mode

4.5.4 Setting the Bandwidths and Sweep Time – BW Key

The BW key calls a menu for setting the resolution bandwidth (RBW), video bandwidth (VBW) and sweep time (SWT) for the frequency sweep. The parameters may be coupled dependent on the span (stop minus start frequency) or freely set by the user. When working with a split screen display, the settings always refer to the active window.

The R&S FSU offers resolution bandwidths from 10 Hz to 20 MHz (FSU43: 10 Hz to 10 MHz) in 1, 2, 3, 5, 10 steps and additionally 50 MHz (not FSU43) as maximum bandwidth.

Resolution bandwidths up to 100 kHz are realized using digital bandpasses with Gaussian characteristics. As far as the attenuation characteristic is concerned they behave like analog filters but have a much higher measurement speed than comparable analog filters. This is due to the fact that the transient response can be compensated as a result of an accurately defined filter behavior.

Bandwidths above 100 kHz are realized using decoupled 5-circuit LC filters.

As an alternative to the analog filters, FFT filters are available for the bandwidths between 1 Hz and 30 kHz. When working with bandwidths up to 30 kHz, the FFT algorithm offers considerably higher measurement speeds with all the other settings remaining the same. The reason is that with analog filters the sweep time required for a particular span is proportional to (Span/RBW however, the sweep time is proportional to (Span/RBW).

). When using the FFT algorithm,

The video bandwidths are available in 1, 2, 3, 5, 10 steps between 1 Hz and 10 MHz (to 30 MHz for resolution bandwidth > 10 MHz, not R&S FSU43). They can be set in accordance with the resolution bandwidth.

The video filters serve for smoothing the displayed trace. Video bandwidths that are small compared to the resolution bandwidth average out noise peaks and pulsed signals, so that only the signal average is displayed. If pulsed signals are to be measured, it is recommended to use a video bandwidth that is large compared to the resolution bandwidth (VBW ≥ 10 × RBW) for the amplitudes of pulses to be measured correctly.

For analog and digital filters, the R&S FSU has overload reserves of different magnitude above the reference level. Due to the LO breakthrough the overload display OVLD responds with digital filters with RBW < 100 kHz, as soon as the start frequency is selected < 6 × RBW; for RBW = 100 kHz as soon as the start frequency is below 3 MHz.

RES BW MANUAL

VIDEO BW MANUAL

SWEEPTIME MANUAL

RES BW AUTO

VIDEO BW AUTO

SWEEPTIME AUTO

COUPLING RATIO

! RBW / VBW SINE [1/3]

RBW / VBW PULSE [0.1]

4.21 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

RBW / VBW NOISE [10]

RBW / VBW MANUAL

SPAN / RBW AUTO [50]

SPAN / RBW MANUAL

DEFAULT COUPLING

FILTER TYPE

Side menu

MAIN PLL BANDWIDTH

FFT FILTER MODE

VBW MODE (LIN LOG)

The BW key opens a menu for setting the resolution bandwidth, the video bandwidth, the sweep time and their couplings.

The …BW AUTO softkeys are used to couple the functions. The coupling ratios are selected by means of the COUPLING RATIO softkey.

RES BW MANUAL

The …BW MANUAL softkeys allow a parameter to be entered. This parameter is not coupled to the other parameters.

With the …BW AUTO softkeys the resolution bandwidth, the video bandwidth and the sweep time can be entered separately for the frequency domain (span > 0 Hz) and the time domain (span = 0 Hz).

But with …BW MANUAL softkeys the selected values apply to both the frequency and time domain.

The RES BW MANUAL softkey activates the manual data entry for the resolution bandwidth.

The resolution bandwidth can be selected in 1/2/3/5/10 steps in the range between 10 Hz and 20 MHz (R&S FSU43: between 10 Hz and 10 MHz). Additionally a maximum bandwidth of 50 MHz (not R&S FSU43) is available. The nominal resolution bandwidth is the 3 dB bandwidth.

When FFT filters are used, the lower limit of the bandwidth is 1 Hz. FFT filters may be used with bandwidths up to 30 kHz.

For numeric inputs, the values are always rounded to the nearest possible bandwidth. For rotary knob or UP/DOWN key inputs, the bandwidth is adjusted in steps either upwards or downwards.

For filter type CHANNEL or RRC, the bandwidth is selected from the list of available channel filters given in section “Filter Types” on page 4.26.

For data entry, the cursor keys Uu and Ud scroll through this list.

The manual input mode of the resolution bandwidth is indicated by a green asterisk (*) on the display.

Remote command: BAND:AUTO OFF;

BAND 1MHz

Operating Manual 1313.9646.12 - 02 4.22

R&S FSU Instrument Functions

Analyzer Mode

VIDEO BW MANUAL

SWEEPTIME MANUAL

The VIDEO BW MANUAL softkey activates the manual data entry for the video bandwidth.

The video bandwidth can be selected in 1/2/3/5/10 steps in the range between 1 Hz and 10 MHz.

For numeric inputs, the values are always rounded to the nearest possible allowed bandwidth. For rotary knob or UP/DOWN key inputs, the bandwidth is adjusted in steps either downwards or upwards.

The manual input mode of the video bandwidth is indicated by a green asterisk (*) on the display.

Remote command: BAND:VID:AUTO OFF;

BAND:VID 10 kHz

The SWEEPTIME MANUAL softkey activates the manual data entry for the sweep time. At the same time, the coupling of the sweep time is cancelled. Other couplings (VIDEO BW, RES BW) remain effective.

In the frequency domain (span > 0 Hz) and for resolution bandwidths above 1 kHz, the allowed sweep times for spans > 3.2 kHz range from 2.5 ms through to 16000 s. With spans below 3.2 kHz, the maximum allowed sweep time is reduced to 5 s * span/Hz.

If FFT filters are used, the sweep time is fixed by the span and the bandwidth and therefore cannot be set.

RES BW AUTO

In time domain (span = 0 Hz), the range of sweep times is 1 µs to 16000 s is selectable in steps of max. 5% of the sweep time. For numeric inputs, rounding is made to the nearest possible sweep time. For rotary knob or UP/DOWN key inputs, the sweep time is adjusted in steps either downwards or upwards.

The manual input mode of the sweep time is indicated by a green asterisk (*) on the display. If the selected sweep time is too short for the selected bandwidth and span, level measurement errors will occur. This happens because the available settling time for the resolution or video filters is too short. In this case, the R&S FSU outputs UNCAL on the display and marks the indicated sweep time with a red asterisk (*).

Remote command: SWE:TIME:AUTO OFF;

SWE:TIME 10s

The RES BW AUTO softkey couples the resolution bandwidth to the selected span. Changing the span causes automatic adjustment of the resolution bandwidth.

Automatic coupling of resolution bandwidth to span is always recommended when a favorable setting of the resolution bandwidth in relation to the selected span is desired for the measurement under request.

The coupling ratio is set in the COUPLING RATIO submenu.

The RES BW AUTO softkey is only available in the frequency domain (span > 0 Hz). The softkey is deactive in the time domain.

Remote command: BAND:AUTO ON

4.23 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

VIDEO BW AUTO

SWEEPTIME AUTO

The VIDEO BW AUTO softkey couples the video bandwidth to the resolution bandwidth. If the resolution bandwidth is changed, the video bandwidth is automatically adjusted.

The coupling of the video bandwidth is always recommended when the minimum sweep time is required for a selected resolution bandwidth. Narrower video bandwidths require longer sweep times due to the longer settling time. Wider bandwidths reduce the signal/noise ratio.

The coupling ratio is set in the COUPLING RATIO submenu.

The coupling of the video bandwidth to the resolution filter is also permitted for the time domain display (span = 0).

Remote command: BAND:VID:AUTO ON

The SWEEPTIME AUTO softkey couples the sweep time to the span, video bandwidth (VBW) and resolution bandwidth (RBW). The sweep time is automatically adjusted on any change in span, resolution bandwidth or video bandwidth.

The softkey is only available in the frequency domain (span >0 Hz). It is blanked in the time domain.

The R&S FSU always selects the shortest sweep time possible without falsifying the signal. The maximum level error compared to using a longer sweep time is < 0.1 dB. If additional bandwidth and level errors are to be avoided, the sweep time is to be set to three times the time offered in coupled mode.

COUPLING RATIO

Remote command: SWE:TIME:AUTO ON

The COUPLING RATIO softkey opens a submenu for selection of the coupling ratios.

RBW / VBW SINE [1/3]

RBW / VBW PULSE [0.1]

RBW / VBW NOISE [10]

RBW / VBW MANUAL

SPAN / RBW AUTO [50]

SPAN / RBW MANUAL

When the default setting is active, i.e. the COUPLING RATIO softkey is deactivated (not highlighted), the ratio span/resolution bandwidth (SPAN/RBW) is 50 (this corresponds to SPAN / RBW AUTO [50]) and the ratio resolution bandwidth/video bandwidth (RBW/VBW) is 0.33 (this corresponds to RBW / VBW SINE [1/3]).

If the ratio RBW/VBW or SPAN/RBW is different from the default setting, the COU- PLING RATIO softkey is highlighted.

The softkeys RBW/VBW... are selection keys. Only one softkey can be enabled at any one time. The softkeys are only effective for the VBW AUTO selection in the main menu.

The softkeys SPAN/RBW... are also selection keys. They are only effective for the RBW AUTO selection in the main menu.

Operating Manual 1313.9646.12 - 02 4.24

R&S FSU Instrument Functions

Analyzer Mode

RBW / VBW

SINE [1/3]

RBW / VBW PULSE [0.1]

RBW / VBW

NOISE [10]

The RBW / VBW SINE [1/3] softkey sets the following coupling ratio:

video bandwidth = 3 × resolution bandwidth.

This is the default setting for the coupling ratio resolution bandwidth/video bandwidth.

This is the coupling ratio recommended if sinusoidal signals are to be measured.

Remote command: BAND:VID:RAT 3

This setting is only effective for the VBW AUTO selection in the main menu.

The RBW / VBW PULSE [0.1] softkey sets the following coupling ratio: video bandwidth = 10 × resolution bandwidth or

video bandwidth = 10 MHz (= max. VBW).

This coupling ratio is recommended whenever the amplitudes of pulsed signals are to be measured correctly. The IF filter is exclusively responsible for pulse shaping. No additional evaluation is performed by the video filter.

Remote command: BAND:VID:RAT 10

This setting is only effective for the VBW AUTO selection in the main menu.

The RBW/VBW NOISE [10] softkey sets the following coupling ratio: video bandwidth = resolution bandwidth/10

RBW / VBW

MANUAL

SPAN / RBW

AUTO [50]

At this coupling ratio, noise and pulsed signals are suppressed in the video domain. For noise signals, the average value is displayed.

Remote command: BAND:VID:RAT 0.1

This setting is only effective for the VBW AUTO selection in the main menu.

The RBW/VBW MANUAL softkey activates the manual input of the coupling ratio.

The resolution bandwidth/video bandwidth ratio can be set in the range 0.001 to

1000.

Remote command: BAND:VID:RAT 10

This setting is only effective for the VBW AUTO selection in the main menu.

The SPAN/RBW AUTO [50] softkey sets the following coupling ratio: resolution bandwidth = span/50

This coupling ratio is the default setting of the R&S FSU

Remote command: BAND:RAT 0.02

This setting is only effective for the RBW AUTO selection in the main menu.

4.25 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

SPAN / RBW

MANUAL

DEFAULT COUPLING

FILTER TYPE

The SPAN/RBW MANUAL softkey activates the manual input of the coupling ratio.

The span / resolution bandwidth ratio can be set in the range 1 to 10000.

If you set the coupling ration via remote control, the value is the reciprocal of the value that you set via the softkey (RBW / Span).

Remote command: BAND:RAT 0.1

This setting is only effective for the RBW AUTO selection in the main menu.

The DEFAULT COUPLING softkey sets all coupled functions to the default state (AUTO). In addition, the ratio RBW/VBW is set to SINE [1/3] and the ratio SPAN/ RBW to 50 in the COUPLING RATIO submenu (default setting, COUPLING RATIO softkey not highlighted).

Remote command: BAND:AUTO ON

BAND:VID:AUTO ON SWE:TIME:AUTO ON

The FILTER TYPE softkey opens the selection list for different filter types. In the range up to 30 kHz digital band filters with Gaussian characteristic and filtering with FFT algorithm can be selected.

4.5.4.1 Filter Types

The R&S FSU provides the following filter types.

Normal (3 dB) Filter

The resolution bandwidths are implemented by Gaussian filters (analog 5-pole filter) with the set 3 dB bandwidth. The resolution bandwidths correspond approximately to the noise bandwidth. For bandwidths up to 100 kHz, digital bandpass filters with a perfect Gaussian shape are used.

EMI (6 dB) Filter

The resolution bandwidths are implemented by Gaussian filters with the set 6 dB bandwidth and correspond approximately to the pulse bandwidth. For bandwidths up to 120 kHz, digital bandpass filters are used. The RBW 10 Hz, 100 Hz, 200 Hz, 1 kHz, 9 kHz, 10 kHz, 100 kHz, 120 kHz and 1 MHz are available

FFT Filter

An FFT is performed. For that purpose, the filtered IF signal is digitized and then transformed into the spectral domain via FFT. The transformation range depends on the selected filter bandwidths and can be set between 4 kHz to 50 kHz. If the span is larger than the transformation range, several transformations are performed and the results are appended to each other in the spectral domain.

Operating Manual 1313.9646.12 - 02 4.26

R&S FSU Instrument Functions

Analyzer Mode

If the span is smaller than the transformation range, the measurement results are interpolated when the number of measurement points provided by the FFT is smaller than the number of display points in horizontal direction (625). A flattop window serves as a window in the time domain so that high amplitude precision with good selection is achieved.

Sweep time Defined by the selected bandwidth and span (reason: FFT fil-

tering is a block transformation). It cannot be changed (softkey deactivated).

Detector Sample detector and peak detector are available. Peak detec-

tor is active when AUTO SELECT is selected.

Video bandwidth Not defined in case of FFT; therefore cannot be set (softkeys

deactivated).

Compared to bandpasses, FFT filters lead to significantly reduced sweep times. For a span of 50 kHz and a bandwidth of 100 Hz, for instance, the sweep time is reduced from 5 s to 40 ms. FFT filters are particularly suitable for stationary signals (sinusoidal signals or signals that are continuously modulated in time). For burst signals (TDMA) or pulsed signals, normal filters are preferable.

As soon as the FFT filters are active (RBW ≤ 30 kHz) the sweep time display field (SWT) is replaced by the acquisition time (AQT) display field.

FFT is a block transformation so the result depends on the time relation between the data set to be transformed and the burst or pulsed signal. A gated sweep measurement for TDMA signals is therefore not provided if FFT filters are used.

Channel Filter

Additionally, a number of especially steep-edged channel filters are available for power measurements.

The indicated filter bandwidth describes the 3 dB bandwidth.

When you select a channel filter, the automatic coupling of RBW to the span is not available.

4.27 Operating Manual 1313.9646.12 - 02

R&S FSU Instrument Functions

Analyzer Mode

The table below shows a list of available channel filter.

Filter Bandwidth Filter Type Application

100 Hz

200 Hz

300 Hz

500 Hz

1 kHz

1.5 kHz

2 kHz

2.4 kHz

2.7 kHz

3 kHz

3.4 kHz

4 kHz

4.5 kHz

5 kHz

6 kHz

7.5 kHz

8.5 kHz

9 kHz

10 kHz

12.5 kHz

14 kHz

15 kHz

16 kHz

20 kHz

21 kHz

25 kHz

30 kHz

50 kHz

CFILter

SSB

DAB, Satellite

ETS300 113 (12.5 kHz channels)

AM Radio

CDMAone

ETS300 113 (20 kHz channels)

ETS300 113 (25 kHz channels)

PDC

CDPD, CDMAone

100 kHz

150 kHz

192 kHz

200 kHz

300 kHz

500 kHz

1.0 MHz

1.2288 MHz

1.5 MHz

2.0 MHz

3.0 MHz

5.0 MHz

5.6 MHz

6 MHz

6.4 MHz

CFILter

FM Radio

PHS

J.83 (8-VSB DVB, USA)

CDMAone

DAB

DVB-T (Japan)

J.83 (8VSB DVB, USA)

DVB-T

Operating Manual 1313.9646.12 - 02 4.28

R&S FSU Instrument Functions

Analyzer Mode

RRC Filter

Filters with root-raised cosine characteristic (RRC) available for power measurements

The indicated filter bandwidth is the 3 dB bandwidth. For RRC filters, the fixed roll-off factor (alpha) is also indicated.

When you select an RRC filter, the automatic coupling of RBW to the span is not available.

The table below shows a list of available channel filter.

Filter Bandwidth Filter Type Application

6 kHz, α=0.2 RRC APCO

18 kHz, α=0.35 RRC TETRA

24.3 kHz, α=0.35 RRC IS 136

1.28 MHz, α=0.22 RRC

3.84 MHz, α=0.22 RRC

MAIN PLL BANDWIDTH

FFT FILTER MODE

4.096 MHz, α=0.22 RRC

Remote command: SENS:BAND:RES:TYPE NORM | PULSe | FFT |

CFIL | RRC

The MAIN PLL BANDWIDTH softkey defines the bandwidth of the main PLL of the synthesizer of the R&S FSU and thus influences the phase noise of the R&S FSU.

Three bandwidth settings are available (Wide, Normal and Narrow). If AUTO is selected, the bandwidth is set automatically (default).

Remote command: BAND:PLL AUTO

The softkey FFT FILTER MODE allows to specify between the following three options for FFT filters:

WIDE: The FFT filters with the greater partial span (this is the span which is

covered with one FFT analysis) are used always.

AUTO: The firmware decides whether to use wide or narrow filters to achieve

the best performance of the measurement.

NARROW: The FFT filters with the smaller partial span are used, this allows mea-

surements near a carrier with reduced reference level, because of a more narrow analog prefilter.

Remote command: SENS:BWID:FFT WIDE | AUTO | NARR

4.29 Operating Manual 1313.9646.12 - 02

Rohde&Schwarz FSU, FSU-B9, FSU-B10, FSP-B16, FSU-B18 Operating Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Basic Safety Instructions

Instrucciones de seguridad elementales

Customer Support

Documentation Overview

1 Putting into Operation

2 Getting Started

2.1 Introduction

2.2 Measuring the Spectra of Complex Signals

2.2.1 Intermodulation Measurements

2.3 Measuring Signals in the Vicinity of Noise

2.4 Noise Measurements

2.4.1 Measuring noise power density

2.4.2 Measurement of Noise Power within a Transmission Channel

2.4.3 Measuring Phase Noise

2.5 Measurements on Modulated Signals

2.5.1 Measurements on AM signals

2.5.2 Measurements on FM Signals

2.5.3 Measuring Channel Power and Adjacent Channel Power

2.5.4 Amplitude Distribution Measurements

3 Manual Operation

4 Instrument Functions

4.1 Introduction

4.5 Analyzer Mode

4.5.3.1 Electronic Attenuator

4.5.4.1 Filter Types