GW Instek GRF-1300A User Manual

RF & Communication Trainer

GRF-1300A

STUDENT BOOK

USER MANUAL and TEXT BOOK

GW INSTEK PART NO. 82RF-1300AM01

ISO-9001 CERTIFIED MANUFACTURER

This manual contains proprietary information, which is protected by copyright. All rights are reserved. No part of this manual may be photocopied, reproduced or translated to another language without prior written consent of Good Will Corporation.

The information in this manual was correct at the time of printing. However, Good Will continues to improve its products and therefore reserves the right to change the specifications, equipment, and maintenance procedures at any time without notice.

Good Will Instrument Co., Ltd. No. 7-1, Jhongsing Rd., Tucheng Dist., New Taipei City 236, Taiwan.

Table of Contents

SAFETY INSTRUCTIONS ................................................................ 2

ABOUT THIS BOOK ....................................................................... 5

INTRODUCTION to the GRF-1300A ............................................... 6

Package Contents .................................................................................................... 8

Product Specifications and Function........................................................................ 8

Usage Instructions .................................................................................................. 9

OVERVIEW of the TIME and FREQUENCY DOMAIN.................... 16

Observation from a different perspective................................................................16

AN INTRODUCTION to SPECTRUM ANALYZERS ........................ 24

Broadband Receiver ................................................................................................24

Attenuator ..............................................................................................................25

Resolution Bandwidth Filter....................................................................................25

Detector .................................................................................................................27

Video Bandwidth Filter ...........................................................................................27

RF COMMUNICATION and SIGNALS EXPERIMENTS.................. 31

Experiment 1: Basic Operation of a Spectrum Analyzer...........................................32

Experiment 2: Measuring a Baseband Waveform.....................................................36

Experiment 3: Different Baseband Waveforms and their Harmonic Measurement...40

Experiment 4: Measurement of the RF Carrier.........................................................47

Experiment 5: AM Signal Measurement ..................................................................60

Experiment 6: FM signal measurement ...................................................................70

Experiment 7: Using a Spectrum Analyzer in Communication Systems ...................81

Experiment 8: Measurement of communication products .......................................88

Experiment 9: Production Line Applications ...........................................................91

Experiment 10: Mixer ..............................................................................................96

TEST for LEARNING OUTCOMES .............................................. 108

APPENDIX .................................................................................. 117

dBm Conversion Table ..........................................................................................117

The relationship between dB and dBc ...................................................................118

Resistor Values in π-type Resistance Attenuators..................................................119

Resistor Values in T-type Resistance Attenuators ..................................................120

Modulation Index and Sideband Amplitude Comparison Table .............................121

Declaration of Conformity.....................................................................................122

GRF-1300A User Manual and Teaching Materials

SAFETY INSTRUCTIONS

This chapter contains important safety instructions that should be followed when operating and storing the GRF-1300A. Read the following before any operation to ensure your safety and to keep the GRF-1300A in the best condition.

Safety Symbols

These safety symbols may appear in this manual or on the instrument.

WARNING

CAUTION

Warning: Identifies conditions or practices that could result in injury or loss of life.

Caution: Identifies conditions or practices that could result in damage to the GRF-1300A or to other objects or property.

DANGER High Voltage

Attention: Refer to the Manual

Protective Conductor Terminal

Earth (Ground) Terminal

Do not dispose electronic equipment as unsorted municipal waste. Please use a separate collection facility or contact the supplier from which this instrument was purchased.

Safety Guidelines

General Guideline

CAUTION

• Do not place heavy objects on the device.

• Do not place flammable objects on the device.

• Avoid severe impact or rough handling that may damage the

device.

• Avoid discharges of static electricity on or near the device.

• Use only mating connectors, not bare wires, for the terminals.

• The device should only be disassembled by a qualified technician.

Safety Instructions

Power Supply

WARNING

Fuse

WARNING

(Measurement categories) EN 61010-1:2010 specifies the measurement categories and their requirements as follows. The device falls under category I.

• Measurement category IV is for measurement performed at the source of a low-voltage

installation.

• Measurement category III is for measurement performed in a building installation.

• Measurement category II is for measurement performed on circuits directly connected

to a low voltage installation.

• Measurement category I is for measurements performed on circuits not directly

connected to Mains.

• AC Input voltage: 100 ~ 240V AC, 50 ~ 60Hz.

• Connect the protective grounding conductor of the AC power cord

to an earth ground to prevent electric shock.

• Fuse type: 1A/250V.

• Only qualified technicians should replace the fuse.

• To ensure fire protection, replace the fuse only with the specified

type and rating.

• Disconnect the power cord and all test leads before replacing the

fuse.

• Make sure the cause of the fuse blowout is fixed before replacing

the fuse.

Cleaning the GRF-1300A

Operation environment

• Disconnect the power cord before cleaning the device.

• Use a soft cloth dampened in a solution of mild detergent and

water. Do not spray any liquid into the device.

• Do not use chemicals containing harsh products such as benzene,

toluene, xylene, and acetone.

• Location: Indoor, no direct sunlight, dust free, almost non-

conductive pollution (Note below) and avoid strong magnetic fields.

• Relative Humidity: < 80%

• Altitude: < 2000m

• Temperature: 0°C to 40°C

(Pollution Degree) EN 61010-1:2010 specifies pollution degrees and their requirements as follows. The device falls under degree 2.

Pollution refers to “addition of foreign matter, solid, liquid, or gaseous (ionized gases), that may produce a reduction of dielectric strength or surface resistivity”.

• Pollution degree 1: No pollution or only dry, non-conductive pollution occurs. The

pollution has no influence.

• Pollution degree 2: Normally only non-conductive pollution occurs. Occasionally,

however, a temporary conductivity caused by condensation must be expected.

• Pollution degree 3: Conductive pollution occurs, or dry, non-conductive pollution

occurs which becomes conductive due to condensation which is expected. In such conditions, equipment is normally protected against exposure to direct sunlight, precipitation, and full wind pressure, but neither temperature nor humidity is controlled.

Storage environment

• Location: Indoor

• Relative Humidity: < 70%

• Temperature: -10°C to 70°C

GRF-1300A User Manual and Teaching Materials

Disposal

Do not dispose this device as unsorted municipal waste. Please use a separate collection facility or contact the supplier from which this instrument was purchased. Please make sure discarded electrical waste is properly recycled to reduce environmental impact.

Power cord for the United Kingdom

When using the device in the United Kingdom, make sure the power cord meets the following safety instructions.

NOTE: This lead/appliance must only be wired by competent persons

WARNING: THIS APPLIANCE MUST BE EARTHED IMPORTANT: The wires in this lead are coloured in accordance with the following code: Green/ Yellow: Earth Blue: Neutral Brown: Live (Phase)

As the colours of the wires in main leads may not correspond with the coloured marking identified in your plug/appliance, proceed as follows:

The wire which is coloured Green & Yellow must be connected to the Earth terminal marked with either the letter E, the earth symbol or coloured Green/Green & Yellow.

The wire which is coloured Blue must be connected to the terminal which is marked with the letter N or coloured Blue or Black.

The wire which is coloured Brown must be connected to the terminal marked with the letter L or P or coloured Brown or Red.

If in doubt, consult the instructions provided with the equipment or contact the supplier.

This cable/appliance should be protected by a suitably rated and approved HBC mains fuse: refer to the rating information on the equipment and/or user instructions for details. As a guide, a cable of 0.75mm2 should be protected by a 3A or 5A fuse. Larger conductors would normally require 13A types, depending on the connection method used.

Any exposed wiring from a cable, plug or connection that is engaged in a live socket is extremely hazardous. If a cable or plug is deemed hazardous, turn off the mains power and remove the cable, any fuses and fuse assemblies. All hazardous wiring must be immediately destroyed and replaced in accordance to the above standard.

Introduction to the GRF-1300A

ABOUT THIS BOOK

This textbook was developed in conjunction with the GRF1300A RF & Communication Trainer and the GSP-730 3GHz spectrum analyzer as an RF communications education system. It not only offers detailed examples, but also the practical knowledge necessary for RF measurements, such as spectrum analyzer principals, as well as AM and FM communication systems.

For you to easily understand the contents of this textbook, we have included as many pictures and diagrams as possible to strengthen your comprehension.

This book is divided into a teacher version and two student versions. All experiment results are included in the teacher edition. In addition, chapters with an asterisk (*) indicate additional text for advanced reading not present in the student addition. Students will not be affected by the omission of the additional text. To further help students, the student edition will contain a “Notes” section in these missing areas.

GRF-1300A User Manual and Teaching Materials

INTRODUCTION to the GRF-1300A

The GRF-1300A is a well designed training kit capable of producing a 3MHz baseband signal and a carrier signal up to 900MHz. The GRF-1300A is also able to perform AM and FM RF circuit experiments as well. The practical exercises in the training kit meet the needs of most general RF courses. The GRF-1300A consists of three modules, namely: a baseband module, an RF Synthesizer/FM module and an AM module. The baseband module can simulate a baseband signal and includes sine, square or triangle waveforms. Its output frequency and amplitude are adjustable. During experiments the three kinds of waveforms can be arbitrarily switched back and forth to meet the signaling requirements of each of the different experiments.

The RF Synthesizer/FM module is used to generate an adjustable carrier frequency as well as perform frequency modulation. This module covers some of the focus points in the RF circuit theory. This will be highlighted in practical experiments in later chapters. FM waveforms can also be produced by using this module together with the baseband module. The GSP-730 spectrum analyzer can be used to observe the various characteristics of an FM waveform.

The AM module and baseband module can be used together to perform amplitude modulation experiments. The GSP-730 Spectrum Analyzer can be used to observe the various characteristics of an AM waveform.

The mixer can convert the RF signal into an intermediate frequency signal or it can do the opposite and convert the intermediate frequency signal into an RF frequency signal in order to transmit or process the carried message, respectively.

This experiment system can be connected to a computer via the USB interface. The interface can be used to turn individual circuits on or off so that students can perform diagnostic experiments.

Students can learn the fundamental aspects of RF theory through a variety of experiments. Understanding RF theory has been made easier by breaking the RF circuits into fundamental

Figure A-1. The GRF-1300A control panel

Introduction to the GRF-1300A

functions. This allows students to see in detail how the theory relates to the practical aspects of the RF circuitry.

This system is a collection of different functions: signal

generation, frequency modulation, amplitude modulation,

communication and other functions. Connecting different modules together can create a number of different RF circuit experiments. Specific experiments will be highlighted in later chapters. The GRF-1300A RF & Communication Trainer is designed to modulate an audio signal with a carrier waveform. The system takes into account the difficulties arising from RF circuit theory and knowledge. It focuses on these theories and sets up experiments to understand the theoretical aspects of RF circuitry – This also has the added benefit of increasing a student’s interest to learn RF circuits.

Figure A-2. Reference platform: GSP730 Spectrum Analyzer

GRF-1300A User Manual and Teaching Materials

Package Contents

This package contains the GRF-1300A unit, RF cable – 3 * 10cm, 1*20cm,RF cable 2* 80cm, a user manual CD, a student book, an antenna, a power cord and so on.

Title Photo No Note

GRF-1300A

RF wire

Antenna

AC power cord

Adapter

3 100mm

1 200mm

2 800mm

2 800-1000MHz

100-240V～50-60Hz

User manual and

software

1 N-SMA Adapter

Student Textbook

Product Specifications and Function

Base Band

RF/FM Analysis

Function Item Spec.

Waveforms Sine, Square, Triangle

Frequency Range

Amplitude

Harmonics Distortion ≤-30dBc

Frequency Accuracy ±0.15MHz

Adjustable Range

Power Range ≥-15dBm Max Frequency Deviation

Peak Difference ≥-18dBm

RF & Communication

Trainer

0.1~3MHz (Triangle-0.1~1MHz) Step: 10kHz

≥1.5Vpp ≥0.75Vpp into 50Ω

≥45MHz (870M~920M)

Step: 1MHz

>3MHz

Mixer LO+IF ≥-35dBm

Introduction to the GRF-1300A

LO-IF

≥-35dBm

Mixer+modulation ≥-60dBm

Bandpass Filter

Communication

Usage Instructions

Procedure

1. For safety purposes, please connect the unit to the correct AC

power source: 100V~240V, 50-60Hz.

Make sure the ground terminal is properly earthed to prevent electric shock.

2. The power socket and USB port are on the rear panel. The

power switch is on the upper left-hand side of the device.

Frequency Centre:

Bandwidth:±20MHz

2.4GHz

Turn circuits on or off by remote command for the diagnostic experiments.

Figure A-3. Connection diagram between different modules

USB port

AC socket

Power switch

3. When using several modules together at the same time,

connect each module with the appropriate RF cable.

4. The UP and DOWN buttons on the Baseband module can be

GRF-1300A User Manual and Teaching Materials

used to adjust the frequency of the baseband signal. The baseband module is adjustable in 10kHz steps.

• WAVE Select is used to select three different baseband

waveforms. When the waveform is selected, the corresponding LED light will be lit up.

• The Reset button is used to reset the GRF-1300A. When

reset, the GRF-1300A will output a 0.10MHz sine wave baseband signal and a carrier signal with a frequency 880MHz.

• The output port is used to output the set baseband signal.

• The four-digit display is used to display the frequency of

the output baseband signal.

• TP4 (test point 4) is used to used to monitor the output

signal from the output port.

• The potentiometer knob is used to adjust the voltage of the

output baseband signal. Turn clockwise to increase the amplitude and turn anticlockwise to decrease its amplitude.

Figure A-4. Baseband module

5. The UP and DOWN buttons on the RF Synthesizer / FM

module can be used to adjust the frequency of the carrier. The carrier can be adjusted in 1MHz steps.

Introduction to the GRF-1300A

Figure A-5. RF Synthesizer/FM module

• The Four-digit display is used to display the frequency of

the carrier signal.

• FM in port and RF / FM Output port are used to receive

the FM signal and output the carrier signal respectively.

• TP2, TP3 and TP1 are used to monitor for breaks in the

circuit. For the position of each test point, please see Figure A-7.

Figure A-6. AM module

6. The AM module is used for amplitude modulation. The AM

in port and RF in port are used to input the modulating signal and the carrier signal respectively. The AM output port outputs the amplitude modulated waveform.

GRF-1300A User Manual and Teaching Materials

Figure A-7. Circuit location of each test point

7. There are five test points (Tp1, Tp2, Tp3, Tp4, Tp5) on the

panel. These five test points are set at different points in the circuit path of the connected modules. Their specific locations are as shown in the Figure below. They are turned on or off by their corresponding relays (B1, B2, B3, B4, B5). An oscilloscope can be used to detect/determine the status of the circuitry at these test points.



1

3

4

2

8. Install the GRF-1300A driver onto the PC.

• Connect the GRF-1300A to the PC. Below are the steps for

installing the software. Add the install software to the install directory. Click next and a window as shown below appears.

Introduction to the GRF-1300A

Figure A-8. Software installation

• Next, click on the “Continue Anyway” button to continue

the installation until the installation procedure is complete.

Figure A-9. Installation procedure is complete

• After the software installation is complete, users can

perform a system error check by sending commands to the GRF-1300A using Hyper Terminal.

GRF-1300A User Manual and Teaching Materials

Figure A-10. Operation interface for HyperTerminal

Introduction to the GRF-1300A

9. Below is a table listing each instruction and a description of

each function.

Instruction Function

*IDN? Returns the manufacturer, model name and

serial number.

RF? Returns the value on the digital display of the

FM/RF module.

AF?

WAVE? Returns the waveform type on the baseband

Bn? (n is the relay number for the corresponding test point)

WAVE:0 The waveform to sine. WAVE:1 Set the waveform to triangle. WAVE:2 Set the waveform to square. Bn:0 ( ‘n’ is the relay

number. I.e., B1:0) Bn:1 ( ‘n’ is the relay

number. I.e., B3:1) AF:N(N is setting frequency) RF:N(N is setting frequency)

Returns the value on the digital display on baseband module.

module.

Returns the state (open or closed) of the currently selected relay.

Set the relay of corresponding no. to OFF.

Set the relay of corresponding no. to ON.

Set the AF frequency to N.

Set the RF frequency to N.

GRF-1300A User Manual and Teaching Materials

OVERVIEW of the TIME and

FREQUENCY DOMAIN

Observation from a different perspective

When a signal is said to be in the time domain, it means that the signal is expressed as a function of time. For example, if we describe a sine wave signal that repeats once each microsecond (μsec, 10-6), it means that the period of the signal is 1 microsecond. Usually we use an oscilloscope to measure these signal characteristics in the time domain. In addition, when we talk about the rise and fall time of a square waveform, we also can observe that in the time domain. Phase delay is also measured in the time domain. Oscilloscopes are well-known electrical signal measurement instruments that perform measurements in the time domain.

1μsec sine wave

However, when we observe a sine wave and a square wave with the same amplitude and period, is there a way to describe the difference between them? Frequency domain measurements just provide a different view point.

First we will explain what frequency domain means. Frequency domain means to observe the frequency composition of a signal. If we add a sine wave signal that has a 1 microsecond period to a spectrum analyzer, we will see an obvious signal on the scale at 1 megahertz (MHz). We know that frequency is the inverse of period. Therefore, a sine wave with a period of microsecond has a frequency of 1MHz. You can measure voltage

Square wave with the same period

Overview of the Time and Frequency Domain

from an oscilloscope and power (dBm) from a spectrum analyzer. Voltage and power can be converted from one to the other, so both of them can be used to display the strength of a signal. Here we introduce a basic concept first. Each frequency point in the spectrum represents a sinusoidal wave (could be a sine or cosine) of a single frequency.

What about a square wave? We will now explain how a square waveform and sine waveform are different to each other in the frequency domain. If we input a square wave with a period of 1 microsecond into a spectrum analyzer, its waveform performance (we usually to say its spectrum or frequency distribution) is as follows.

If we compare it with a sine wave spectrum, we can observe that in addition to the point at the1MHz scale, other signal points also appear at higher frequencies and with decreased amplitudes. Therefore it shows that a square wave also includes a combination of signals that are multiples of the frequency baseband in addition to the 1MHz base frequency (fundamental frequency).

We can see a classic relationship between the time domain and frequency domain in the illustration below. A square wave signal in the time domain can be decomposed into multiple basic harmonic waves. The distribution of these harmonic components can be clearly seen in the frequency domain. Frequency domain analysis describes the characteristics of a signal from another viewpoint.

GRF-1300A User Manual and Teaching Materials



Time domain Frequency domain

Overview of the Time and Frequency Domain

NOTES

GRF-1300A User Manual and Teaching Materials

NOTES

Overview of the Time and Frequency Domain

NOTES

GRF-1300A User Manual and Teaching Materials

NOTES

Overview of the Time and Frequency Domain

NOTES

GRF-1300A User Manual and Teaching Materials

AN INTRODUCTION to SPECTRUM

ANALYZERS

Spectrum analyzers are one of the most important instruments for RF microwave measurements. Being familiar with spectrum analyzers in general is very important for operating high frequency microwave equipment or for performing communication measurements. In addition, being familiar with the basic operating principals will allow you to quickly understand other related test equipment. In this chapter, we will briefly introduce the basic working principles of the spectrum analyzer. After understanding the basic working principles, you will find that a spectrum analyzer can be a handy tool to use.

Broadband Receiver

The principal function of a spectrum analyzer is to convert the input signal frequency down to a frequency (band) that detection circuitry can handle. For example, a 2.4GHz signal needs to be down-converted to several MHz before the Detection & Display unit can process the signal. Therefore a spectrum analyzer must be able to reduce the frequency band down to several MHz. The first half of a spectrum analyzer is called the radio frequency module and its task is to reduce the input signal frequency. A mixer and a bandpass filter are used to decrease the frequency (they can raise the frequency as well). The mixer is a component with three ports: two inputs and one output. Assume that the two input frequencies on input port are fRF and fLO respectively, and then the output frequency will be f

is made of two signals of different frequencies (fLO- fRF and

IF. fIF

fLO+ f signal is the sum of the input signals and the other is the difference. Determining which of the IF signals that will be used depends on the system and subsequent bandpass filter design. As for why the three ports are named after RF, LO, IF, they are just the conventional terms that are used.

) that appear on the output port at the same time. One

Figure B-1. The basic structure of a broadband receiver

Attenuator

An Introduction to Spectrum Analyzers

Mixers

RF Input

Next, we are going to introduce the other basic functional

BPFs

Tunable LOs

Detection & Display

Unit

blocks that a spectrum analyzer is composed of. These blocks are often mentioned when instructed on how to use a spectrum analyzer.

An attenuator on the RF input path can increase the dynamic range of the input signal level or provide more input protection to the spectrum analyzer. Referring to Figure B-2, the attenuator limits the signal level coming to the mixer (RF end) to a certain level. If the input signal is above a reference level, it can cause measurement errors, or cause spurious noise.

Figure B-2. Attenuator



RF Input

Attenuator

Resolution Bandwidth Filter

When the input signal frequency is converted to an IF, a RBW (resolution bandwidth) filter is used to distinguish the signals that are close to each other in frequency. Figure B-3 shows this concept.

Mixers

BPFs

Tunable LOs

Detection & Display

Unit

GRF-1300A User Manual and Teaching Materials

Figure B-3. Basic structure of a resolution bandwidth filter

Figure B-4. The effect of different RBWs (1)



RF In

Attenuators

Mixers

Tunable LOs

BPFs

RBW Filter

Detection & Display

Unit

Figure B-4 shows how two different RBW filters distinguish between two signals that are close to each other in frequency. The bandwidth of RBW2 is wider that of RBW1.

Signal under test

RBW

Results

RBW1

After passing the narrower RBW1 filter, the components of

RBW2

the two tone signal are clearly distinguished from each other as a result. But in the wider RBW2 filter, the result is not as clear as RBW1. We can predict that if the resolution bandwidth of RBW2 is wider, we could even misinterpret the result as only one signal. This will also happen if these two signals are even closer together in frequency.

Another case is when the amplitude of one signal is much higher than the other; the smaller signal can still be detected using RBW1, but it is obscured if RBW2 is used. Figure B-5 illustrates this difference. This is why these filters are known as resolution bandwidth filters.

An Introduction to Spectrum Analyzers

Figure B-5. The effect of different RBWs (2)

Detector

Signal under test

RBW

RBW1

RBW2

Following the RBW filter, the detector detects the power and coverts it to DC voltage via an ADC so that it can be displayed.

Figure B-6. Detector

Video Bandwidth Filter

Figure B-7. VBW filter

However, a filter is employed after the detector to filter out the noise generated by the detector. This is the function of the VBW (video bandwidth) filter as shown in Figure B-7.

GRF-1300A User Manual and Teaching Materials

Figure B-8. Different VBWs

Figure B-8 shows how the VBW affects the displayed output. If the signal under test passes through two different VBW filters, in which VBW1 is less than VBW2, we can see that the magnitude of the noise floor of VBW2 is greater than that in VBW1. But notice that the average level of the noise floor remains the same. The VBW filter only averages the noise level; It doesn’t affect the overall amplitude of the signal noise floor.



VBW

Signal under

Results

Noise

VBW1 VBW2

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