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\\NTI_SVR1\Instdata\ RA P ID-TEST\RT-1M\U_Manual\text\RT1M332.doc
8VHU0DQXDO
>@9
Multitone Audio Test System
Version 3.32 E
For Firmware Revision
3.25 and higher
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User Manual
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INTERNATIONAL WARRANTY
Limited Warranty
NEUTRIK guarantees the >@9 system and its components against defects in material or
workmanship for a period of one year f rom the date of original purchase for use and agrees
to repair or replace any defective unit at no cost for either parts or labor.
Important
This warranty does not cover damage resulting from accident, misuse or abuse, lack of
reasonable care, the affixing of any attachment not provided with the product, loss of parts
or connecting the product to any but the specif ied receptacles. This warranty is void unless
service or repairs are performed by an authorized service center.
No responsibility is taken for any special, incidental, or consequential damages. In case of
damage please take or ship prepaid your
>@9 System to your nearest authorized service
center. Be sure to include your sales invoice as proof of pur chase date. All transit damages
that may eventually occur are not covered by this warranty.
Note
No other warranty, written or oral, is authorized by NEUTRIK. Except as otherwise stated in
this warranty NEUTRIK makes no representation or warranty of any kind, expressed or
implied in law or in fact, including, without lim itat ion, im plied merc hantabilit y or f itness f or any
particular purpose and assumes no liabilit y, either in tort, strict liability, contract or warranty
for products.
NEUTRIK AG
Im Alten Riet 34
FL-9494 SCHAAN
Liechtenstein
Tel: +41 (0)75 / 237 24 24
Fax: +41 (0)75 / 232 53 93
WARNING! Read this manual and especially chapter
2 I
NSTALLATION
carefully before
operating the instrument. Important information about mains voltage
selection and fuse rating are given there.
Do never open, modify or try to repair this instrument unless properly
instructed by an authorized service technician or NEUTRIK.
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CE DECLARATION OF CONFORMITY
We, the m anufacturer
NEUTRIK CORTEX Inst r um ents AG
Im Alten Riet 34
FL-9494 Schaan
hereby declare that the product
Product Name
Rapid-Test
Model Number
RT-1M
Serial No
.
Year of Construction
1996
conforms to the following standards or other normative documents
EC-Rules
89/392, 91/368, 93/44, 93/68, 73/23, 89/336, 92/31
Harmonized Standards
IEC 65, IEC 68-2-31, IEC 348
EN50081-1, EN50082-1, EN50140, EN 61010-1
This declaration becomes void in case of any changes on the product without written
authorization by NEUTRIK.
Date
Schaan, 12. August 1996
Signature
Position of Signatory
Product Manager Test Instrument s
Samples of this instrument have been tested and found to conform
with the statutory protective requirements. Instruments of this type
thus meet all requirements to be given the CE mark.
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TABLE OF CONTENTS
1 OVERVIEW ....................................................................................... 9
Communication................................................................................................. 9
Accessories & Options .....................................................................................10
Software Tools.......................................................................................................10
Application Notes...................................................................................................10
DTMF Option.........................................................................................................10
Microphones & Phantom Power Supply.................................................................10
2 INSTALLATION................................................................................... 11
Unpacking......................................................................................................... 11
Rack Mount ......................................................................................................11
AC Power Connection......................................................................................11
Mains Cable......................................................................................................12
IEEE Connection..............................................................................................12
IEEE Address Selection.........................................................................................12
Audio Connection.............................................................................................12
Balanced Connection.............................................................................................13
Unbalanced Connection.........................................................................................13
Battery Low Indication............................................................................................13
LED Indicators..................................................................................................14
Power....................................................................................................................14
Interface ................................................................................................................14
Calculating.............................................................................................................14
Trigger...................................................................................................................14
Overload................................................................................................................14
Error ......................................................................................................................14
Test of Function................................................................................................15
HT-BASIC Program Example.................................................................................15
3 SYSTEM DESCRIPTION ...................................................................... 16
Multitone Signals..............................................................................................16
Multitone Parameter...............................................................................................17
Sampling Rate...................................................................................................17
Blocklength.......................................................................................................18
Frequency Spacing...........................................................................................18
Bins...................................................................................................................19
Phase / Crest Factor Optimization.........................................................................19
Comparability of Multitone Measurements.............................................................20
Signal Table...........................................................................................................20
Blocklength 512.................................................................................................20
Blocklength 1024...............................................................................................21
Blocklength 2048...............................................................................................21
Blocklength 4096...............................................................................................21
Blocklength 8192...............................................................................................21
Generator .........................................................................................................22
Block Diagram.......................................................................................................22
Digital Section........................................................................................................22
Analog Section.......................................................................................................22
Analyzer............................................................................................................23
Block Diagram.......................................................................................................23
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Analog Section.......................................................................................................23
Filtering.............................................................................................................23
Digital Section........................................................................................................24
Definition of Multitone Signals..........................................................................24
Header...................................................................................................................25
Multitone Signal.....................................................................................................26
Data Acquisition................................................................................................26
Wake-up Sequence...............................................................................................26
Synchronization Mode............................................................................................26
INTernal............................................................................................................26
INTNoheader.....................................................................................................27
EXTernal...........................................................................................................27
EXTNoheader ...................................................................................................27
Gathering Data......................................................................................................27
Signal Analysis & Result Queries.....................................................................28
Level......................................................................................................................28
Distortion...............................................................................................................28
RMS and RSS Value.........................................................................................29
Interpretation of TD+N.......................................................................................29
Distortion Plot....................................................................................................29
Full Band TD+N Measurement..........................................................................30
THD+N Calculation ...........................................................................................30
MT-SINAD.........................................................................................................30
RSS Selective Measurement.............................................................................31
Noise.....................................................................................................................32
Full Band Noise.................................................................................................32
Crosstalk................................................................................................................33
Phase....................................................................................................................34
DTMF Mode......................................................................................................34
Broadcast Mode ...............................................................................................35
Mode of Operation.................................................................................................35
Setup.................................................................................................................35
Trigger Configuration ........................................................................................36
Application Hints / Troubleshooting...................................................................37
4 PROGRAMMING................................................................................. 39
Command Structure .........................................................................................39
IEEE-488.1 Compatibility.......................................................................................39
IEEE-488.2 Commands.........................................................................................39
Command Summary ..............................................................................................39
Descriptive Symbols..............................................................................................40
Command Notation................................................................................................41
Command Set...................................................................................................42
SYSTem Subsystem..............................................................................................42
SYSTem:RESet ................................................................................................42
SYSTem:ERRors?............................................................................................42
SYSTem:INFormation?.....................................................................................43
INPut Subsystem...................................................................................................44
INPut:FRONt [ON¦OFF].....................................................................................44
INPut[1-2]:LINK [OFF¦ON].................................................................................44
INPut[1-2]:RANGe <Range> <Unit>..................................................................44
INPut:SYNC [INTernal¦INTNoheader¦EXTernal¦EXTNoheader] ........................45
INPut:SWFilter [OFF¦CWE¦CCITT]....................................................................45
INPut:DEEMphasis [OFF¦ON]...........................................................................46
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INPut:TRIGger:ARMed......................................................................................46
INPut:TRIGger:ARMed?....................................................................................46
INPut:TRIGger:BREak......................................................................................47
INPut:TRIGger:CONFiguration [LOOSE¦TIGHT¦USER]....................................47
INPut:TRIGger:USRConfiguration
<setbin1(dB)>,<setbin2(dB)>,<emptybin(dB)>..........................................47
INPut:TRIGger:USRConfiguration?...................................................................48
INPut[1-2]:STATus?..........................................................................................48
OUTPut Subsystem...............................................................................................49
OUTPut:MTONe:PARameter <Parameter>.......................................................49
OUTPut[1-2]:LEVel <Level> <Unit> ..................................................................49
OUTPut:MTONe:PRETriggerlength <Length> ..................................................50
OUTPut:MTONe:MTONelength <Length>.........................................................50
OUTPut[1-2]:BINlevel <Level> <Unit>...............................................................51
OUTPut[1-2]:MUTe [OFF¦ON]...........................................................................51
OUTPut:FLOAT [OFF¦ON]................................................................................51
OUTPut:MTONe:ACTive [1¦2¦3¦4]......................................................................52
OUTPut:MTONe:STARt....................................................................................52
OUTPut:MTONe:CONtinuous ...........................................................................52
OUTPut[1-2]:STATus?......................................................................................52
OUTPut:MTONe:NAME?................................................................................... 53
OUTPut:MTONe:BLOCklength?........................................................................53
OUTPut:MTONe:PARameter?..........................................................................53
OUTPut[1-2]:MTONe:CRESt?...........................................................................54
MEASurement Subsystem.....................................................................................55
MEASurement[1-2]:LEVel:UNIT [dBVp¦Vp¦dBV¦V] ............................................55
MEASurement[1-2]:LEVel?...............................................................................55
MEASurement[1-2]:DISTortion:UNIT [dBV¦V]....................................................55
MEASurement[1-2]:DISTortion?........................................................................55
MEASurement[1¦2]:MTSinad?...........................................................................56
MEASurement[1-2]:SELectiverss:UNIT [dBV¦V]................................................56
MEASurement[1-2]:SELectiverss? <binstart> <binstop>...................................57
MEASurement[1-2]:NOISe:UNIT [dBV¦V]..........................................................57
MEASurement[1-2]:NOISe?..............................................................................57
MEASurement[1-2]:CROSstalk:UNIT [dB¦%].....................................................58
MEASurement[1-2]:CROSstalk?.......................................................................58
MEASurement:PHASe:UNIT [rad¦deg]..............................................................58
MEASurement:PHASe:SCALe <Scale>............................................................58
MEASurement[1-2]:PHASe?.............................................................................59
MEASurement1:DTMF:STARt...........................................................................59
MEASurement1:DTMF?....................................................................................59
Device Status.........................................................................................................60
*STB?................................................................................................................60
*OPC.................................................................................................................60
*OPC?...............................................................................................................60
*CLS..................................................................................................................61
*ESE.................................................................................................................61
*ESE? ...............................................................................................................61
*SRE.................................................................................................................61
*SRE?...............................................................................................................62
*ESR?...............................................................................................................62
*PSC.................................................................................................................62
*PSC?...............................................................................................................63
*IDN?................................................................................................................63
*RST.................................................................................................................63
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*TST?................................................................................................................63
*WAI..................................................................................................................64
Examples..........................................................................................................64
Use of an *OPC command ...........................................................................64
Use of MAV bit in the status Byte register.....................................................64
IEEE Standard Status Data Structure....................................................................65
5 APPLICATION HINTS .......................................................................... 66
Arbitrary Generator...........................................................................................66
Alignment and Adjustments for Audio Repair Facilities....................................66
Cellular Phone Testing.....................................................................................66
Rub & Buzz Speaker Testing............................................................................66
RT-EVAL Software Package............................................................................67
Units & Conversion...........................................................................................67
6 SPECIFICATIONS............................................................................... 69
Generator ......................................................................................................... 69
Analyzer............................................................................................................69
General............................................................................................................. 69
7 INDEX .............................................................................................. 70
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1 OVERVIEW
The trend in modern audio testing is to reduce more and more the time required for a
complete performance test of the device being tested. This tendency results partly from the
demand of broadcasters being forced to provide 24hour prog ramming, leaving little time f or
testing. In a modern st udio with dozens of input channels, several routing paths and more
than 24 recording channels, a complete test including all parts of t he studio becomes very
time-consuming and boring since the t est s ar e highly repetitive.
Industrial applications also require reduced test time, especially at production lines where
any time wasting process becomes a bottleneck. Reducing t est time by a factor of 20 to 50
ensures for years that testing will not be the lim it ing factor and increases production density.
>@9 is a modern and advanced audio test system with the capability to evaluate the
important performance Parameter of a device within a fraction of a second.
>@9 is a
complete, optimized system, containing a remote controllable generator as well as an
intelligent analyzer, and can be easily integrated into an automated environment. The
system provides the highest performance and specif ications to meet also the requirem ent of
professional equipment.
•
Frequency range
20Hz to 20kHz
•
Output level
-60dBVp to +20dBVp
•
Input range
-60dBVp to +20dBVp
•
Measurements
level, noise, distortion, crosstalk and phase in one step
•
Burst transmission time
typ. 250-960ms
•
Residual distortion
< -86dB
>@9 is very simple in terms of connecting, handling and use within any automated
environment, but highly com plex in terms of the implement ed structures and algorithms to
perform the analysis in a extremely short period of time.
>@9 is very compact, using the most advanced technology available on the market . Within
its case of 19“ width and height of one unit ( 1.75“) only, it provides two generator channels
and two independent analyzer channels. The analyzer and generator can be operated
completely independently even though they are located in the same housing.
There is no external synchronization required to perform the analysis. Each transmitted
multitone signal contains an information header allowing any listening analyzer to
synchronize onto the signal.
Communication
Since >@9 does not provide any control elements, it must be com pletely controlled by a host
PC. Due to performance reasons, an IEEE-488 parallel interface has been integrated into
the instrument. This allows to t ransmit any command independently of the actual generator
and/or analyzer activities. The instruction to transmit a previously defined multitone signal
can be issued from the PC at any time.
Consequently, the basic requirements for the host PC is a standard IEEE-488 interface
board with installed software drivers. Detailed descript ions of the IEEE-488 connection and
all commands are filed in chapters Mains Cable and Programm ing respectively.
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Accessories & Options
Software Tools
Following software packages for >@9 are available free of charge f rom your local NEUTRIK
representative.
• RT-EVAL Evaluation Software
• LabView® Driver Library
• LabW indows® CVI Dr iver Libr ary
Please notice, that for either of these tools a GPIB-interface board from National
Instruments (type GPIB-PCMCIA or GPIB/TNT or GPIB-PCIIA [production year 1992 or
later]) must be installed in your host controller.
Application Notes
The appendix of this User Manual comprises the documents
• Introduction to
>@9
• Get Familiar with Writing Code for
>@9
• Cellular Phone Testing
• Comparison of Conventional vs. Multitone Testing
Additional application notes on speaker testing, external sig nal analysis etc. will be released
in future. Please contact you local NEUTRIK representative for f urther information.
DTMF Option
Optional PCB to be installed internally, allowing to monitor 1 channel on incoming DTMF
(Double Tone Multiple Frequency) signals in parallel to t he nor m a l oper ation (see p. 34).
Microphones & Phantom Pow e r Supply
NEUTRIK provides two measuring microphones for industrial applications.
• 3382 ¼" measuring microphone
• 3384 ½" measuring microphone
To allow the use of these microphones with
>@9, an optional Phantom power box is
available to provide the necessary supply voltage through XLR connectors. The box is
plugged to the input banana connectors and comes along with an AC mains adapter.
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2 INSTALLATION
This chapter is intended as help for proper unpacking and installation of the >@9 system.
Please read it carefully to avoid wrong connections or inconveniences during operation of
the instrument.
Unpacking
>@9 has been carefully packed by NEUTRIK to avoid damages during transportation.
Should the box show severe damages, please immediately check the instrument inside on
external impacts. In case of any visible damage, please do not send the instrum ent back but
contact your local dealer and / or the carrier to avoid loss of claim s for replacement.
Rack Mount
>@9 is designed to mount in a 19“ Rack and occupies one unit of height or rack space
(1.75“) only. Please allow at least 2“ additional depth at the rear side for all necessary
connectors. Make sure there is enough air circulat ion around the unit for cooling purposes
and please do not place
>@9 besides high temperat ure devices such as power amplifiers in
order to avoid overheating.
The specified operating tem perature ranges between 5° and 45°C (40-110F) while humidity
must not exceed 90% R.H. non-condensing.
AC Power Connection
Before connecting t he instrument via mains cable to the power source, mak e sure that the
voltage selector label on the connector / f use holder assembly of the
>@9 system matches
the supply voltage of the local area. If the instrument is not compatible with the available
power source, follow the next paragraph to change the voltage selector.
>@9 can operate from 100VAC, 120VAC and
230VAC sources. To reconfigure t he input line
voltage, remove the power cable and open the
flap of the connector/fuse holder at the rear
side of
>@9. Either press a small screwdriver
into the slot to open the flap as shown in Fig. 1
or ruin your fingernails.
Take out the drum and insert it in the new position so that the mat ching voltage indication
points towards you. At the same time replace the mains f use with the proper current rating.
For voltages of 100V to 120V a slow 2A fuse has to be installed, while for 230V a slow 1A
fuse is appropriate.
After selection of the correct mains voltage and fuse, close the flap and insert the power
cable.
>@9 is designed w ith a protecti ve ground (earth) connection t hrough
the ground wire of the power cord. This connection is essential for
safe operation. Never operate the instrument if safety ground is
unavailable or has been compromised.
Fig. 1 Voltage Selector
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Mains Cable
The enclosed mains power cable has an unconnected end with three colored leads, which
correspond to
Brown = Live (AC)
Blue = Ground
Yellow/Green = Earth
Attach a mains plug to the cable that fits the receptacles of your country.
IEEE Connection
The >@9 system provides an IEEE-488 interface (standard design interface for
programmable instrumentat ion) which is connected to the IEEE bus using a standard IEEE488 interface cable from t he r ear panel illustrated in Fig. 2.
With t he IEEE int erface bus, up t o 31 instruments can
be interconnected. The cables have identical piggyback connectors on each end so that several cables
can be connected in virtually any configuration. T here
must be, of course, a path f rom the computer to every
device operating on the bus.
As a practical matter, avoid stacking of more than
three or four cables to a single connect or. If the stack
gets too long, any for ce on the stack can damage the
connector mounting. Be sure that each connector is
firmly screwed in place.
IEEE Address Selection
Each IEEE device has at least one talk and listen address (unless tot ally transparent or a
talk or listen only device). The address of the
>@9 can be adjusted with the DIP switch at
the rear panel of the instrument (see Fig. 2). Each switch position has a number printed
underneath. The result ing IEEE address is the sum of all numbers, where the switch is in
position “1“. The above illustr ated example has an addr ess selection of 3, since switch 1 and
switch 2 are in position "1". The five switches allow the selection of any address in the range
from "1" to "31" inclusively.
Audio Connection
>@9 features balanced and unbalanced BNC and 4mm banana connectors for both input s
and outputs. Balanced connections enhance the noise and hum immunity and are always
recommended for measurement purposes.
>@9 can also handle unbalanced signals.
Unbalanced signals normally have one hot signal
against chassis ground. For this reason unbalanced
connections are recommended for short connections
only (less than 1m / 3 f eet) or in a relatively noise-free
environment.
You may use either the set of front connectors with two
inputs & outputs or the eq uivalent set of connectors at
the rear panel of the instrument .
Caution: Do not connect both front and rear panel connect ors at the same time
since this may result in signal mismatching.
Fig. 2 IEEE Connector
Fig. 3 Front Connectors
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Connections between an unbalanced DUT
and the balanced inputs of
>@9 should
preferably be made with shielded twisted
pair cables to avoid the introduction of
noise and hum. The shield of such a cable
shall be grounded only on one side.
Grounding the shield on both sides
increases the chance to build ground loops.
Balanced Connection
Balanced connections with two BNC cables can be realized by connecting them to the
>@9
HIGH and LOW inputs. The ground shells of both connectors are wired to ground. Do not
connect the shields toget her on the instrument side of the DUT but leave them open. With
balanced connections do not assemble the short circuit bar.
You may also use banana inputs instead of BNC inputs. The respective HIGH and LOW
inputs of the BNC and banana connectors are inter nally wired toget her .
Caution: For balanced signals make sure that not only the front ground connection
is disassembled but also the ground bar at the rear panel!
Unbalanced Connection
If you use the HIGH input only of >@9
for connecting t he hot out put of t he DUT,
use the BNC cable’s shield as the retur n
signal (common of the DUT output).
When using t he generator in unbalanced
mode, the available level will always be
6dB (50%) below the defined level.
Battery Low Indication
>@9 contains a battery for backup purposes of the internal memories. Life expectancy of
the battery is about t en years. Should the battery become low, the 'Error' LED will blink 3 to 4
four times after a start-up and Error 220 Battery low (memory backup) is generated.
Fig. 4 Shielded Twisted Pair Cable
Fig. 5 Balanced BNC / Banana Connection
Fig. 6 BNC Cable - Balanced
Fig. 7 Unbalanced Connection
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LED Indicators
During the initial i z at i on period of >@9 system (normally <1s) all LEDs are active. If the
unit is swi t ched ON for the very first time or after a firmware change, it has t o i ni t i al i ze
all its signals and tables. This might take up to a few minutes, depending on the
signal resolution. All LEDs are lit during this peri od.
Power
This LED indicates that the power of the system is switched on,
the internal supply voltages are operating normally and the selftest of the system has been successfully completed.
Should it stay off after switching on the instrument please check
whether the power cable is connected to the system, the voltage
selector is set f or the correct supply voltage and the wall socket is
switched on.
Should the power LED still be off, check the power fuse in the
connector / fuse holder assembly of
>@9. Please refer to AC
Power Connection to see how to open it.
WARNING Do not try to do further repairs. Call your local dealer for support.
Interface
This LED indicator lights up if the IEEE interface is busy and receives a command. It
remains illuminated until the user has read t he answer from the interface. In st andby mode
with no activity on the IEEE interface the LED is of f.
Calculating
Whenever FFT or filtering calculations are performed this LED lights up.
Trigger
This LED indicator g oes on as soon as a >@9 trigger has been successf ully detected and
remains lit until the user has read the result ( s) from the buffer.
Overload
Should the input signal overload one or both channels, the LED indicator goes on. This
happens if the maximum input voltag e of 20dBu (10V) is exceeded or if a higher voltage t han
the selected range is applied. In such a case the error LED also lights up. The overload LED
resets with the next measurement and the ranges set cor r ectly.
Error
>@9 handles an error queue internally. Whenever an error is detected – hardware or
software – the error LED comes on. It disappears as soon as the error number has been
queried through the IEEE inter face.
Fig. 8 LED Indicators
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Test of Function
After connection of the cables and proper setting of the IEEE address it is recommended to
run the subsequent short progr am to conf irm the pr oper f unction of t he system.
>@9 can be
operated with any operating system providing an IEEE-488 interface.
HT-BASIC Program Example
10 ! RT-1M Demo Program
20
30 Adr=11 ! enter IEEE address here
40
50 Adr=Adr+700 ! evaluate output/enter address J
51 GOSUB 900 ! read device informations
60 OUTPUT Adr;"Output:Mtone:Active 1" END
65 OUTPUT Adr;"Output:MTone:Start" END ! measurement loop
70 OUTPUT Adr;"Measurement1:Level?" END ! terminate output with END
80 GOSUB 1000 ! read the measurements
90 PRINT
100 GOTO 65
110 STOP
900 ! read system information
905 DIM Inf$[100]
910 OUTPUT Adr;"System:Information?" END
920 ENTER Adr;Inf$
930 PRINT Inf$
940 RETURN
1000 ! interpret incoming data stream
1010 DIM Rcv$[1000]
1020 DIM X$[10]
1030 DIM Y$[20]
1040
1050 ENTER Adr;Rcv$ ! read data A
1060 Xpos=POS(Rcv$,"/") ! find X/Y separator
1070 Ypos=POS(Rcv$,",") ! find Y/X separator
1080
1090 WHILE (Xpos>0) AND (Ypos>0) ! as long as there are separators do:
1100 X$=Rcv$[1,Xpos-1] ! isolate X value
1110 X=VAL(X$) ! convert X string to value A
1120 Ypos=POS(Rcv$,",") ! find Y/X separator
1130 IF Ypos>0 THEN ! is there another value? >
1140 Y$=Rcv$[Xpos+1,Ypos-1] ! isolate Y value
1150 ELSE
1160 Y$=Rcv$[Xpos+1,LEN(Rcv$)] ! isolate Y value
1170 END IF
1180 Y=VAL(Y$) ! convert Y string to value
1190 Rcv$=Rcv$[Ypos+1,LEN(Rcv$)] ! delete the read XY pair from string
1200 Xpos=POS(Rcv$,"/") ! find next X/Y separator
1210 PRINT "Bin# ",X,"Meas: ",Y
1220 END WHILE
1230 RETURN
1240 END
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3 SYSTEM DESCRIPTION
Multitone Signals
Traditionally, audio testing stimulates the device under test (DUT) with a sinusoidal signal.
This type of signal is relatively easy to handle and distortion measurements may be
performed by simply notching out the sing le frequency.
Fig. 9 Time Plot of Sinusoidal Signal Fig. 10 Spectrum of Sinusoidal Signal
More advanced tests like intermodulation distortion measurem ents stimulate the device with
a pair of sinusoidal signals to come closer to t he real situation of audio signal transmission.
In the presence of nonlinear transfer char acteristics, the DUT generat es new harmonic and
intermodulation frequencies.
However, in practice the device is normally stimulated by music or speech which is a far
more complex signal than any single or twin tone test. Many frequencies with non-correlated
phase relations exist in such a real-world signal.
Therefore, multit one testing is a much more realistic approach for audio testing, emulating
the complex structure of natural sound. A mult itone signal typically contains 2 to ~31 signal
frequencies, each with a certain phase relation, distributed over the frequency band of
interest. Obviously, sophisticated test inst ruments are necessary to analyze all these signals
with their interactions on each other.
Fig. 9 and Fig. 10 show a typical multitone signal in the time- and frequency domain. It is
important to know that the waveform of the time plot strongly correlates with the phase
relations between its single frequencies. Since t he max. amplitude of the t ime signal directly
determines the dynamic range of both t he DUT and the analyzer, a low peak value is both
important and desirable.
0 10 20 30 40 50 60 70 80 90
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Tme [ms]
Ampli tude
2
0.5 1
1.5
Frequency [kHz]
Amplitude [ dB ]
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
1.5
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Obviously, it is necessary to characterize the time signal by an appropriate value in order to
allow the optimization of its phase relations. The most suitable value for this purpose is the
Crest factor
, which is defined as
Crest factor
Peak Value
RMS Value
=
_
_
Equation 1 Crest Factor
For any (multitone) signal with g iven RMS value, the Crest factor will change with the peak
value, which in turn depends on t he phases of the signal components. An optimal dist r ibut ion
of the phases result s in a low peak value of the resulting time signal and theref ore a low
Crest factor (refer also to chapter Phase / Crest Factor Optimization).
NEUTRIK provides in its RT -EVAL software package a sophisticated algorithm to optimize
the phases of a mult itone signal. Please contact your local r epresentative to get a f ree copy
of this software
.
Multitone Parameter
>@9 is a digital processing system that analyzes the transmitted signal by using Fast
Fourier Transformation (FFT) and calculates with its DSP all desired results out of the
digitized samples.
For proper use and programming of
>@9 it is vital to understand the core param eter of this
analysis as well as their relationships. Consequently, the most important definitions and
formulas are explained below.
Sampling Rate
Every digitization process, i.e. conversion of an analog signal into a digital bit stream and
vice versa, has to be accomplished at a certain
sampling rate
(number of samples per
second). The sampling rate deter m ines t he analog bandwidth of the converter.
In
>@9, the sampling rate is 48k Hz, thus providing an analog bandwidth of up to 20kHz.
0 0.002 0.004 0.006 0.008 0.01
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Amplitude
Time
[ms]
0 4 8 12 16 20
Fre
q
uency [kHz
]
-400
-350
-300
-250
-200
-150
-100
-50
0
Amplitude [dB
]
Fig. 11 Time Plot of a Multitone Signal Fig. 12 Spectrum of a Multitone Signal
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Blocklength
The number of samples, t hat are actually used f or one FFT, is called
blocklength
. This value
determines both the duration & the f requency resolution of a multitone signal. In
>@9, the
blocklength may be selected by the user in five steps f r om 512 t o 8192.
[]
MT Block Duration
Blocklengt
h
Sampling Frequency
s=
_
Equation 2 Duration of One Multitone Signal Block
Note A
>@9 multitone burst always comprises several multitone signal blocks,
thus resulting in a far longer duration than the
’MT Block Duration’
.
The blocklength also defines the lowest detect able frequency of the incoming spectrum. For
example, with a blocklength of 512 @ 48kHz sampling rate, a multitone block duration of
10.7ms results, corresponding to a m in. frequency of ∆f = 93. 75Hz (see Equation 3).
Furthermore, it is important to know that only signals with an integral number of periods
(reciprocal value of the signal frequency) fitting into one blocklength may be properly
analyzed by the FFT.
0 100 200
300
400 500
Sample Number
Fig. 13 The 5 Lowest Possible Time Periods @ Blocklength 512
In other words, only frequencies with an integral m ultiple of the lowest detectable frequency called frequency spacing ∆f - m ay be tr ansm it t ed.
Frequency Spacing
The frequency spacing ∆f corresponds to the lowest frequency that can be generated &
analyzed. It defines the spectral resolution of t he FFT and is calculated by following formula.
∆f
Sampling frequency
Blocklength
Hz
Blocklength
==
_’48000
Equation 3 Frequency Spacing
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>@9
Multitone Audio Test System
User Manual
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Only frequencies with an integ ral multiple of ∆f m ay be defined as
signal bins
(see below) of
a multitone burst.
Example
Blocklength = 512 @ 48kHz sampling rate
⇒ ∆f = 93.75Hz
⇒ available frequencies =
n
* 93.75Hz (n = integral number)
Bins
The frequencies, that may be transmitted in a multitone burst, are called
bins
. For a better
understanding, three types of bins have been introduced.
•
Signal bins
are those bins (frequencies) t hat actually build the multitone signal.
•
Even bins
are all the bins (freq uencies) that emerg e from Equati on 3, i.e. the f requencies
that may be used as signal bins in a multitone signal.
•
Odd bins
are an effect the internal FFT computation of >@9. They represent all bins
halfway between the even bins, i.e. as if the freq uency spacing would equal ∆f/2.
The subsequent relations indicate the min. and max. available frequencies (
bins
) in a
multitone signal at 8kHz / 48kHz sampling rate (
f
s
).
{}
f f Hz may be generated onlymin =≥∆20
Equation 4 Minimum Signal Bin Frequency
{}
ff
kHz
f
kHz may be displayedmax *=≤∆
∆
20
20
Equation 5 Maximum Signal Bin Frequency
Besides the above equations there are no other constraint s for the definition of a multitone
signal. This means you can use any bin representing a fr equency below or equal to 20kHz
as a signal bin. I t is up to the operator what the intention of t he signal bins is. Please refer
also to chapter Signal Table.
Phase / Crest Factor Optimization
In order to achieve a low Crest factor, RT-EVAL – an evaluation PC-program provided free
of charge by NEUTRIK - of fers a special feature that allows to optim ize the phases of any
multitone signal. The results can be loaded dir ectly from or back into the
>@9 Generator.
Low Crest factors ar e important for two reasons. First , the peak level of the m ultitone signal
raises the necessary input range for the analysis and ther eby reduces sensitivity for the lowlevel signal components. Second, the low energy content of a multitone signal with high
Crest factor may barely stimulate the DUT.
A non-optimized multitone signal may show Crest factors of up to 10 (20dB), while with a
proper minimization algorithm, Crest factors as low as ~2 (6dB) can be found. This
difference of 14dB can directly enhance or decrease the dynamic range of the analyzing
system.
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Multitone Audio Test System
User Manual
20 / 71 V 3.32
Comparability of Multitone Measurements
One has to be aware that the results of multitone testing cannot be compared directly with
conventionally acquired results. For instance, dist ortion products m ay appear over the entire
band due to the fact that each signal bin produces harm onics and intermodulates with other
signal bins. The strict separation bet ween harmonic distortion and inter modulation cannot be
guaranteed, since at certain signal bins some intermodulation products and harmonic
frequencies may fall to gether, thus influencing t he Distortion as well as the SINAD results..
However, a multitone signal comes much closer to a "r eal-world“ signal than any single tone
test signal. T he results are in qualitative ter ms comparable with conventional measurement
results as long as the specific theory behind multitone testing is considered. With a single
tone stimulus, the achieved results are directly comparable t o conventional analyzers.
Please refer to the corresponding applicat ion note, filed in the appendix of this manual.
Signal Table
>@9 supports five different blocklengths. According to Equation 3 to Equation 5, each
blocklength results in the paramet er of Table 1. Please observe that the minimum signal bin
frequency is ≥20Hz and that the overall duration of a burst always is longer than of a block.
Blocklength Min. Burst Durat ion
(without Header)
Typical Burst
Duration
Generator
Resolution
Analyzer
Resolution
512 154 ms 260 ms 93.8 Hz 46.9 Hz
1024 284 ms 390 ms 46.9 Hz 23.4 Hz
2048 344 ms 450 ms 23.4 Hz 11.7 Hz
4096 684 ms 790 ms 11.7 Hz 5.9 Hz
8192 854 ms 960 ms 5.9 Hz 2.9 Hz
Table 1 Available Blocklengths
Blocklength 512
Frequency spacing ∆f 93.75 Hz
Analyzer resolution 46.875 Hz
Bin_Min (f
min
) 1 (93.8 Hz)
Bin_Max (f
max
) 213 (19.969 kHz)
Table 2 Signal Parameter with Blocklength 512 @ fs=48kHz
0 0.005 0.01 0.015 0.02 0.025
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Crestfactor=7.87
Fig. 14 Non-Optimized Multitone Signal
0 0.005 0.01 0.015 0.02 0.025
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Crestfactor=2.71
Fig. 15 Optimized Multitone Signal
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Multitone Audio Test System
User Manual
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Blocklength 1024
Frequency spacing ∆f 46.875 Hz
Analyzer resolution 23.4375 Hz
Bin_Min (f
min
) 1 (46.9 Hz)
Bin_Max (f
max
) 426 (19.969 kHz)
Table 3 Signal Parameter with Blocklength 1024 @ fs=48kHz
Blocklength 2048
Frequency spacing ∆f 23.4375 Hz
Analyzer resolution 11.71875 Hz
Bin_Min (f
min
) 1 (23.4 Hz)
Bin_Max (f
max
) 853 (19.992 kHz)
Table 4 Signal Parameter with Blocklength 2048 @ fs=48kHz
Blocklength 4096
Frequency spacing ∆f 11.71875 Hz
Analyzer resolution 5.859375 Hz
Bin_Min (f
min
) 2 (23.4 Hz)
Bin_Max (f
max
) 1706 (19.992 kHz)
Table 5 Signal Parameter with Blocklength 4096 @ fs=48kHz
Blocklength 8192
Frequency spacing ∆f 5.859375 Hz
Analyzer resolution 2.9296875 Hz
Bin_Min (f
min
) 4 (23.4 Hz)
Bin_Max (f
max
) 3413 (19.998 kHz)
Table 6 Signal Parameter with Blocklength 8192 @ fs=48kHz
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User Manual
22 / 71 V 3.32
Generator
>@9 comprises a completely independent two-channel 16bit arbitrary g enerator. The digital
section has its own high level microprocessor enabling the system to react flexibly to
external events, communicate with various interfaces and reprog ram the sample counter f or
the arbitrary generator
Block Diagram
MEM 1
MEM 2
MEM 3
MEM 4
ARBITRARY
LOGIC
LED INDICATORS
IEEE-488
INTERFACE
18 BIT D/A CONVERTER
18 BIT D/A CONVERTER
AMP
IMPED.
MUTE
IMPED.
MUTE
AMP
ISOLATION
ISOLATION
CPU
Fig. 16 Block Diagram Generator
Digital Section
The CPU reads the samples out of a non-volatile memory. The memory block provides
capacity for four independent test signals, each with 16 bit resolution and any length def ined
in Table 1. Space is also provided for the header of each signal. The master clock is derived
from a high precision crystal.
Analog Section
The two-channel analog output signal behind the D/A convert ers is fed into a reconstruction
filter, cutting off all freq uencies above 20kHz. On its way the signal also passes through an
electrical isolation to keep the complete analog output section floating. The programmable
output amplifier of fers a balanced signal with 150Ω output impedance (unbalanced 75Ω) at
any level in steps of 0.1dB between -60dBVp to +20dBVp.
Analyzer
The >@9 analyzer consists of a two channel analog input stage, prepar ing the input signals
for the conversion into digital format. With the converted signals an FFT analysis with the
Page 23
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Multitone Audio Test System
User Manual
V 3.32 23 / 71
same blocklength as of the generated signal is perf ormed. Further analysis of the acquired
result may be done through individual programming .
Additionally, the analyzer also provides facilities to weight an input result with different
weighting curves.
Block Diagram
LED INDICATORS
CLOCK
SYNC
IEEE-488
INTERFACE
A/D CONVERTER
A/D CONVERTER
AMP
AMP
DSP MEMORY
DSP
CPU
Fig. 17 Block Diagram Analyzer
Analog Section
>@9 features two independent analog input stages with completely independent ranging
facilities. The inputs ar e balanced with BNC and 4mm banana connectors at the front and
rear panel. Input impedance is 100kΩ at all inputs. Levels can be handled from 60dBVp to
+20dBVp with full dynamic range.
Filtering
>@9 provides a set of software weighting and Emphasis f ilters. The filters have a gain of 1
and can be disabled or enabled. Only one weighting filter and the Emphasis filter may be
engaged at a time. The curr ent filters implemented are listed on the next page.
Page 24
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User Manual
24 / 71 V 3.32
Filter type Softw are
C-Message
ã
CCITT
ã
750µs Emphasis
ã
The commands INPut[1-2]:RANGe <Range> <Unit> and INPut:DEEMphasis
allow to select
them.
Digital Section
The digital section consists mainly of the DSP and a logic circuitry progr am m ed into a FPGA.
The DSP is used f or all calculat ions - especially the FFT - and to control t he range sett ing of
the analog input amplif iers. The DSP is connected via a bus to the central pr ocessing unit
which manages all communication to the PC and controls the system bus.
Definition of Multitone Signals
>@9 may store up to four independent two-channel multitone signals with up to 31
frequencies in a non-volatile memory. This ensures that no programming or parameter
loading is required before the g enerator can be operated. New signals can easily be loaded
into one of the memory blocks using an IEEE output command. For the correct syntax
please refer to OUTPut:MTONe:PARameter?.
New signals must contain following informat ion
•
>@9 memory-location to store the signal
• Name of the sig nal
• Blocklength (number of samples)
• Number of signal bins for channel 1
• Number of signal bins for channel 2
• Signal bin numbers of channel 1
• Signal bin numbers of channel 2
• Phases of the signal bins for channel 1
• Phases of the signal bins for channel 2
The
memory location
may be defined by a number from 1 to 4.
Name
is a user defined
ASCII string with up to 8 characters. The
blocklength
has to be set to one of the values
defined in Table 1. The
number of signal bins
defines how many frequencies shall appear in
the multitone sig nal for CH1 and CH2; t he minimum is 1 (sinusoidal) sig nal, the maximum is
31 bins. The
signal bin numbers
have to be calculated according to Equation 7. T wo blocks
of
phase
values for CH 1 and CH 2 terminate the definition of a multitone sig nal.
All signal bins have identical am plitudes. The user has the choice either to set the
overall
output level
of the multitone sig nal or, alternatively, the
signal bin level
. Regardless of this
choice, these values may be expressed as peak or RMS levels in linear or logarithmic units
(Vp, V, dBVp, dBV).
The overall output level of a multitone sig nal may be queried at any time. The same goes for
the actual Crest factor, t hat may be queried with the command OUTPut[1-2]:M TONe:CRESt?
Page 25
>@9
Multitone Audio Test System
User Manual
V 3.32 25 / 71
or calculated by using Equation 1. With these two values, the signal bin level may be
calculated according to
U
U
n
with n total number of signal binsbin
out
RMSF
RMS
= =
Equation 6 Bin Amplitude
Following example shall illustrate the signal definit ion procedure. The multitone signal shall
have three signal bins at 300Hz, 1kHz and 3kHz. Both channels ar e identical. The name of
the signal is "Telefon“. Since the three frequencies are fairly wide apart, we may use a
blocklength of 512, result ing in a frequency spacing of 93.75Hz. T o calculate the signal bin
numbers, refer to Equation 7
Bin Round
f
f
Hz
Hz
n
n
===()
.
min
300
93 75
3
Equation 7 Bin Number
Consequently, the bins equaling 300Hz, 1KHz and 3KHz have the numbers 3, 11 and 32.
The definition of the phases can be done manually or by using the Crest fact or optimizer of
RT-EVAL. Finally, the table may look as follows.
1,“Telefon“,512,3,3,3,11,32,3,11,32,-3.141,1.234,0.707,0,0.810,0.111
The duration of this multitone signal (not considering the header explained below) is the
reciprocal value of 93.75Hz which is 10.67ms.
ATTENTION Do never define
exclusively
the three signal bins @ 562.5Hz, 1406.25Hz
and 3.0kHz as multitone signal since these three frequencies form the
trigger of a multitone burst header.
Header
Each multitone burst is preceded by a header comprising tr igger and clock synchronization.
The standard
trigger
signal has a
duration of 42ms and consists of 5 f ixed
frequencies in the voice band with
different levels. By receiving this
frequency / level pattern a listening
analyzer recognizes a
>@9 multitone
signal and wakes up. The pattern has
been selected in a way that the falsetriggering rate due to voice, music or
other synthesized signals, interpreted as
multitone signal, is < 10
-6
.
Additionally, a
pretrigger
signal may be added in order to allow the DUT to stabilize before
transmission of the rest of the multitone signal. See also command OUTPut[1-2]:LEVel
<Level> <Unit>.
During the
Clock Sync
period (SYNC block) with a fixed length of 64ms, the analyzer may
adjust its sampling freq uency to the transmitted clock frequency (3kHz). This ensures that
100
50
Trigger
Clock sync.
3x Multitone
Time [ms]
Fig. 18 Multitone Signal with 5 Bursts as Example
Page 26
>@9
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User Manual
26 / 71 V 3.32
frequency shifts, g enerated by the DUT (modulators / demodulators or tape machines with
speed differences) or slight ly different clock frequencies of a separated generat or / analyzer
pair are eliminated automatically.
Multitone Signal
Right after the header information follows the
multitone signal
itself, i.e. tr ansmission of the
signal bins. The duration of t he multitone signal depends on the block length as defined in
Table 1. The multitone signal is transm itted at least 3 t imes and may be repeat ed by applying
the command OUTPut:MTONe:MTONele ngth. For instance, several multitone block s may be
transmitted before the analysis starts, in order to stabilize the DUT and to let transients
disappear. The analysis itself req uir es a minimum of two blocks.
Data Acquisition
Wake-up Sequence
The >@9 analyzer continuously executes a FFT of the input signal. As long as there is no
signal or any non-correlated audio information, no action is started. But as soon as the
analyzer detects a header, i.e. the
>@9-specific freq uency / level pattern in the input sig nal,
it wakes up and records the incoming multitone signal.
Please notice that the trigger signal can be detected up to -20dB below the set range. That
means for example with an input range set to -6dBu t he trigger can be detected from levels
as low as -26dBu.
Synchronization Mode
Normally, the analyzer of >@9 uses t he internal sample frequency clock of the generat or.
This mode should be used f or all applications where no freq uency shifts occur on the signal
transmission path.
However, in cases where the device under test (DUT) changes the frequency of the
transmitted signal, the analyzer has to synchronize itself ont o the incoming signal itself. For
this purpose, each header of a multitone burst contains a SYNC block, providing a fixed
frequency, onto which the analyzing DSP may synchronize its sampling clock. This feature
and the choice, whether a header shall be transmitted at all, may be activated with command
INPut:SYNC [INTernal¦INTNoheader¦EXTernal¦EXTNoheader], offering the four following
modes.
INTernal
The analyzer is linked to the generator clock of the same unit and the multitone signal is
preceded by a header (t rigger & SYNC block). This mode may be chosen if the m ultitone
burst is generated in the same unit where it is analyzed and if no major frequency shifts
occur in the DUT. The burst is initiated with command OUTPut:MTONe:STARt and
transmission must not show a delay of more than 1s.
INTNoheader
Again, the analyzer is linked to the generator clock of the same unit, but no header is
transmitted. The benef it of t his mode appear in noisy environments, where the trigg er cannot
be detected, and for analysis of signals being generated by the DUT itself. However, the
max. allowable transmission duration is 50ms, i.e. the multitone burst must ’arrive’ at the
analyzer at latest after this time from the moment of it s init iat ion.
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Multitone Audio Test System
User Manual
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EXTernal
In case of expected clock frequency differences between the generator and analyzer the
user has to activate the EXT mode. Freq uency shifts appear e.g . in combination with analog
tape recorders, where t he r ecording and the playback speed are not ident ical, or due to local
separation of generator and analyzer. Up to 1s t ransmission time is allowed.
EXTNoheader
This mode may be used after transmission of several multitone burst transmissions in mode
EXT only. The analyzer synchronizes itself onto the SYNC blocks of these preceding
multitone bursts, before it eventually gathers the burst in mode EXTnoheader .
Gathering Data
After trig gering and synchronization, the analyzer waits one period of the m ultitone burst to
let the transients of t he DUT disappear bef ore it st arts with a two-block FFT . T his calculation
takes - depending on the block leng th - between 48ms and 190ms. The analysis includes
• Decoding of the bit st ream to get two stereo signals
• W indowing with Hanning window (where necessary)
• Organization of bits (bit reverse organization of r esults)
• Calculation of level and phase from the complex spectrum
The calculated vector is placed in the result area of t he m em ory and the DSP is ready for the
next acquisition.
If the user queries for measurement results, the CPU reads these stored data from the
internal memory and computes the required results out of them. This process requires
considerable computations since all the bins have to be read, squared and sum med up for
the results calculation. As soon as this process is finished, the results are transmitted and
thus available for further processing.
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User Manual
28 / 71 V 3.32
Signal Analysis & Result Queries
Level
One core requirement of audio testing is the analysis of the
frequency response
of the DUT.
With the multitone approach, this goal is achieved in one step by measuring the returned
signal bin levels instead of sweeping a single sine signal through the frequency band of
interest.
In practice, the freq uency response can be obtained from a transmitted multitone signal by
plotting the received signal bin level values. Please notice that this analysis considers the
energies of the sig nal bins only, but not
the distortion + noise energy in the bands between
the signal bins.
Fig. 19 Level Plot
Keep in mind, that the
overall input level
, i.e. the total energy of all received
signal bin +
(unused) bin levels
would correspond to the RMS level of the received multitone signal
(signal bin levels + distortion + noise).
However, this value is of almost no interest for t he charact erization of a DUT, since it reflects
its overall attenuation / amplification only, but not the frequency response.
Distortion
Basically,
distortion
is a measure to characterize the nonlinear behavior of a DUT, i.e. the
degree of how it generates new signal components at other frequencies than the one(s) of
the stimulating signal. T herefore, The
>@9 returns as distortion result s the
total distortion +
noise energies
(TD+N) for the bands between the sig nal bins of a multitone signal.
Remains the question, in which way
>@9 actually calculates the TD+N values in the
frequency bands of interest. The answer can be given by considering the equat ions for the
RMS and RSS value.
RMS and RSS Value
Purely analog test instruments evaluate the distor tion energy as
RMS
voltage (Root Mean
Square) by summing up all received signal components
V
i
according to following equation.
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Multitone Audio Test System
User Manual
V 3.32 29 / 71
V
V
n
with n number of signal components
RMS
i
in
==
=
∑
()
..21
Equation 8 RMS Calculation
Unfortunately, when applying this f ormula on the discrete spectrum of a FFT analysis, the
result correlates in inverse proportion to the block length / number of bins in the respective
band. Therefore, to calculate the TD+N result out of a dig itized signal, the
RSS
value (Root
Sum Square) has to be used.
V V withi counter over all bins n m
RSS i
inm
==
=
∑
() (..)
..
2
Equation 9 RSS Calculation
The accuracy of this approach can be proved with any spectral analyzer. The better the
resolution (i.e. the higher the block length), the lower is the amplitude of a single bin, since
the total energy of the band is constant . Consequently, the summing-up of the bins always
result in the same value, regardless of the chosen resolution (blocklength).
Interpretation of TD+N
To interpret the T D+N value correctly, it has to be considered that this result slig htly differs
from a conventionally measured
THD+N
value. With conventional T HD+N analysis, a single
tone stimulates the DUT. This f requency component is subtracted from the received signal
after transm ission. The ratio of the remaining level to the to tal input level gives the THD+N
and
SINAD
result respectively.
On the other hand, the transmission of a multitone stimulus will result in the appearance of
many harmonics and intermodulation products. However, it is neither possible to relate any
of these signal components to a certain signal bin of the original multitone signal, nor to
differentiate the r eceived signal between harmonics and intermodulation products.
Distortion Plot
Fig. 20 shows a typical distortion plot, derived from the retur ned distortion results of >@9.
• The first value in the plot
D1
equals the RSS result (TD+N value) of the band between the
first bin ≥20Hz up to the last bin < SignalBin#1.
• All further r esults
Dn
represent the bands between the first bin > SignalBin#n up to the
last bin < SignalBin#n+1.
• The last distortion result represents the band between the first bin above the highest
signal bin up to the last bin ≤ 20kHz.
Please notice, that both the even & odd bins of t he received signal are considered for the
TD+N calculation.
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30 / 71 V 3.32
Frequency [Hz]
Amplitude
Signal
Bin 1
Signal
Bin 2
Signal
Bin n
Signal
Bin 3
Bin
Max
Bin
Min
D1
D2
D..
Fig. 20 Distortion Plot
Full Band TD+N Measurement
To evaluate the TD+N value in the full freq uency band (20Hz-20kHz), following equat ion has
to be applied.
TD N D V D V D V
FullBand n
+= +++
1
2
2
22
[] [] ... []
Equation 10 Full Band TD+N
wherein
D1-D
n
are the returned distortion results, expressed in [ V] .
THD+N Calculation
To evaluate the THD+N value of a DUT, the following requirements have to be met.
• Stimulation of the DUT with a single bin
signal.
• Calculation of the THD+N value (in %) according to
THD N
DV DV
DV LV DV
+=
+
++
[%]
[] []
[] [] []
*
1
2
2
2
1
2
1
2
2
2
100
Equation 11 THD+N Calculation
with
D
1
= distortion between 20Hz and the signal bin,
D
2
= distortion between the signal bin
and 20kHz and
L
1
= received signal bin level.
MT-SINAD
For some applications, the SINAD result - being the reciprocal of THD+N - is r equired.
SINAD
Signal Noise Distortion
Noise
Distortion
=
++
+
Equation 12 SINAD Definition
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Obviously, to get a true SINAD result , it is necessary to stim ulate the DUT with a sing le sine
tone only. Otherwise, i.e. if a multitone signal is applied, intermodulation products would
appear, thus increasing the
Noise+Distortion
value. Nevertheless, it is also possible to
calculate the SINAD re sult out of a transmitt ed multitone signal. However, in order to avoid
misunderstandings, this result is called MT-SINAD herein.
Actually, with >@9, just use the query command MEASurement[1¦2]:MTSinad?, to get the
calculated value.
In practice, the MT-SINAD result m ay differ slightly from a conventionally measured SINAD
value, due to intermodulation products between the signal bins. However, in qualitative
terms, the results are eq ual as pr oven in numerous setups.
RSS Selective Measurement
The
MEASurement[1-2]:SELectiverss? <binstart> <binstop> command allows to query the TD+N
result of a user-defined band anywhere between 20Hz and 20kHz. Both the lower and the
upper border of this band may be set freely to any bin number - they don’t have to be
identical to the signal bins of the transmitted multitone sig nal.
Frequency [Hz]
Bin_Start Bin_Stop
Amplitude
Signal
Bin 1
Signal
Bin 2
Signal
Bin 3
Bin
Max
Bin
Min
Fig. 21 RSS Selective Plot
NOTE Be aware, that if a signal bin is within the band of interest, the RSS
selective result will represent the
signal bin level + distortion + noise
.
The RSS selective feat ure is especially helpful, if a certain component of a received signal
shall be investigated. For instance, after transmission of a single tone signal, it allows to
evaluate the individual harmonics of the fundamental frequency.
Noise
As for distortion analysis, the noise measur ement divides the frequency band in subbands,
split by the signal bins, and calculates the noise values of these subbands.
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Frequency [Hz]
Amplitude [dB]
20k
Signal 1
Bin a
Signal 2
Bin b
Signal n
Bin x
Signal 3
Bin c
Bin
Max
Bin
Min
a+1
Noise
Band 1 Band 2 Band 3 Band n
Band (n+1)
b-1
Fig. 22 Noise Plot
Consequently, a multitone measurement with
n
signal bins results in
n+1
noise values, each
calculated internally by
>@9 according to the following formula.
()
Noise U RSS value of all odd bins in a band
ii
ia
b
==
−
=+
−
∑
2
21
2
1
1
*
Equation 13 Noise Calculation
NOTE Equation 13 describes the internal
noise calculation of >@9, i.e. the actually
returned noise results must not be re-calculated in any w ay.
Full Band Noise
MeasurementTo evaluate the noise value in the full frequency band (20Hz-20kHz), following
equation has to be applied.
NNVNVNV
FullBand n
=+++
1
2
2
22
[] [] ... []
Equation 14 Full Band Noise
wherein
N1-N
n
are the returned noise results, expressed in [V], of any multitone
measurement.
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Crosstalk
The Crosstalk Plot m ay be calculated only if a st ereo sig nal is tr ansmitt ed. T his ster eo signal
must have separate bins set in the 2 channels in a way that the respective bins remain
unused in each other channel. In case of bad channel separation of the DUT, the unique
frequencies of channel "A" talk into channel "B", i.e. they appear in the received signal of
channel "B" and vice versa.
The crosstalk value is the ratio of t he unused bin level in channel "B" and the active bin level
of channel "A" at the same frequency. It is expressed in % or dB.
Crosstalk
Unused Bin ChB
Set Bin ChA
i
LEFT
i
i
=
__
__
Equation 15 Calculation of Crosstalk
As an example, we may assume that a signal bin with 10dB @ 1kHz is transmitted via
channel "A", while at channel "B" the received bin level @ 1kHz equals -30dB.
Consequently, the crosstalk f r om channel " A" to channel "B" @ 1kHz is 1% or -40dB.
Please note that noise increases the crosstalk value and thereby falsifies the measurement.
Frequency [Hz]
Amplitude
20
20k
Transmitted
Signal
Bin 1a
Received
Signal
Bin 1b
Transmitted
Signal
Bin 2a
Transmitted
Signal
Bin Xa
Received
Signal
Bin 2b
Frequency [Hz]
Amplitude
20
20k
Received
Signal
Bin 1a
Transmitted
Signal
Bin 1b
Received
Signal
Bin 2a
Received
Signal
Bin Xa
Transmitted
Signal
Bin 2b
&KDQQHO$
&KDQQHO%
Fig. 23 Crosstalk Plot
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Phase
Since the analyzer knows all information about the transmitted multitone signal from the
generator, also the phases of t he signal bins ar e available for furt her analysis. Theref or e, the
analyzer may calculate any changes of inter-channel phase relations at each common signal
bin of the 2-channel test signal.
ϕϕ ϕ
ii
Left
i
Right
UU=−()( )
Equation 16 Phase Calculation
However, the exact phase shift between generator output and analyzer input cannot be
calculated due to the unknown time delay of the DUT.
DTMF Mode
The DTMF option extends the measuring capabilit ies of >@9 in the field of phone t esting. It
allows to receive & analyze the standardized DTMF (Double Tone Multiple Frequency) tones
on channel 1.
Every key of a standard 4x4 phone keypad is represented by a dual tone. These tones
comprise the indicated frequencies as shown in Table 7.
1209Hz 1336Hz 1477Hz 1633Hz
697Hz
1 2 3
a
770Hz
4 5 6
b
852Hz
7 8 9
c
941Hz
* 0
#
d
Table 7 DTMF Signal Coding
For instance, the DTMF tone for key #6 is put together of the two frequencies 770Hz &
1477Hz.
The meaning of the f our ’empty’ keys
a-d
in the last row may be user-defined.
The DTMF mode of >@9 may be started and reset by using command
MEASurement1:DTMF:STARt. From then on, the unit continuously monitors the input
channel 1 in parallel to any other operation, and stores all received DTMF tones in an
internal buffer.
This 32 keys wide buffer may be queried by command MEASurement1:DTMF?. To clear t he
contents of the buffer, command MEASurem e n t 1 : DTM F: STARt has to be sent to the unit.
The input range of channel 1 must be adjusted to the level of the DTMF tones to be
analyzed. Please notice that an overload, caused by an incoming DT MF signal, will not be
detected, i.e. the unit will not generate an error message. Furthermore, no DTMF tone
analysis will be possible in such a case.
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Broadcast Mode
The broadcast mode allows to let the analyzer of a >@9 unit wait f or an incoming multit one
burst that has been generated by another, remote >@9 unit (generator & analyzer are
physically apart). By this, it becomes possible to measure e.g. the characteristics of a
transmission line.
Following restrictions have to be considered on behalf of the br oadcast mode.
• The measurements under the broadcast mode can be done in one direction only at a
time. In order to return a multitone burst in the opposite direction, i.e. from the previously
used analyzer to the generator, the operation m ode of both units has to be changed.
• The generator & analyzer must be cont rolled each by a PC through a GPIB interface.
• The transmitt ed m ultitone signal must be defined identically on the generator & analyzer.
• In order to avoid false t riggering, it is vital to thoroughly understand and apply the trigg er
configuration as well as the setting of a proper output level and input range in the
generator and analyzer.
Mode of Operation
The broadcast mode of >@9 is based on the com mand INPut:TRIGger:ARMed. If sent to the
unit, this instruction sets the analyzer to a st ate where it waits until it detect s an incoming >@
9 trigger and receives the connected multitone signal.
The trigger must have been generated by another >@9 instrument and has to match the
trigger conditions defined in t he analyzing unit.
Setup
The complete procedure to set up a broadcast transmission test with >@9 may be
summarized as follows.
1. Install the generator and analyzer at the intended locations and control each of them
with an own PC through GPIB IEEE interf aces.
2. Connect the two units with the ends of the transmission line to be measur ed.
3. W rite an appropriate program to control the unit s. Optionally, you may also install RT-
EVAL V1.60 or higher on both host PCs.
4. Define a multitone signal according to the specific demands of the test (available
bandwidth, number of bins, signal duration etc.) identically
on both the generator and
analyzer. Don’t forget to optimize the Crest factor of the signal (e.g. by using the Crest
optimizer of RT-EVAL).
5. In the analyzer, set the trigger configuration to TIGHT by using command
INPut:TRIGger:CONFiguration [LOOSE¦TIGHT¦USER].
6. Set the SYNC mode of the generator to INTernal with command INPut:SYNC INTernal.
7. Set t he output level of the generator approximately to the level of the broadcast signal.
Make sure that no clipping occurs.
8. Set the SYNC mode of the analyzer to EXTernal with command INPut:SYNC EXTernal.
9. Adjust the input range of the analyzer to the incoming signal level. To do this, connect
the analyzer to the transmitted broadcast signal and reduce the input range until the
Overload LED lights up. Increase the input range by +6dB from this value in order to
provide enough headroom.
10. Set the analyzer to the armed mode with command INPut:TRIGger:ARMed.
11. Interrupt the broadcast signal and transmit the multitone burst with command
OUTPut:MTONe:STARt.
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12. It is recommended to transmit the burst at a defined time, so that the operator of the
analyzer realizes immediately, whether the trigger has been detected or not.
If no successfull line measurements are possible, read the chapter Application Hints /
Troubleshooting (p. 37) to check possible causes and work out solutions.
Trigger Configuration
The most important t opic of broadcast mode measurements with >@9 is the definit ion and
application of an appropriate trigger. For this purpose, three trigger configurations are
provided.
•
LOOSE
- standard configuration for industrial applications (noisy signals with a poor
dynamic range, or internal link between generator & analyzer). The trigger condition is
met rather easily, i.e. false triggerings have to be expected if the multitone signal is
introduced into an ordinary broadcast program et c.
•
TIGHT
- special configur ation for broadcast applications. The tr igger condition has been
tightened by far vs.
LOOSE
in order to avoid false triggerings. Requires an accurate
setting of the generator output level and analyzer input range.
•
USER
- this parameter allows to define the trigger condition according to user-specific
demands. However, since this application requires a very thorough and detailed
understanding of t he whole triggering complex, this approach is f or very advanced users
only, who have a profound understanding of all possibilities and their consequences.
ATTENTION Improper configuration of the USER trigger may result in a ’always’ or
’never’ condition, where the analyzer triggers on almost every incoming
signal (music, speech etc. ) or never recognizes any trigger, even if i t i s a
correct one.
The trigger signal of a >@9 multitone burst comprises three signal bins at different
frequencies and with individual levels. In order to avoid false trigg erings, the receiving >@9
permanently monitors the input signal on strictly this pattern. Furthermore, the analyzer
checks whether two more, predefined signal bins ar e ’empty’, i.e. whether no level can be
detected at these two
frequencies. If this is the
case, the analyzer
recognizes the incoming
signal as a >@9
multitone burst and
triggers to it.
Fig. 24 visualizes the
characteristic of a >@9
triggersignal. The bottom
bars (
T ) at the fre-
quencies 1, 3 and 5 represent the set signal bins
and their amplitudes, defined against the ground
level of the generator,
whereby signal bin 1 and 5 have identical amplitudes. The f requencies 2 & 4 represent the
empty bins.
Amplitude [ dB ]
Frequency
a
12345
cc
b
0dB
a
Fig. 24 Trigger Definition
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Obviously, the levels of the five signal bins, together with their frequencies, make the
uniqueness of the >@9 trigger signal.
The application of the User tr igger allows to individually define the ’headroom’ between the
0dB line and the bottom bars (
T ). However, this is a very delicate operation, and therefor e
not recommended for new users of >@9. Anyway, in case that this feature truly has to be
used, please refer to the explanations of the commands INPut:TRIGger:CONFiguration ...
and INPut:TRIGger:USRConfiguration ... as well as to the helpfile of t he RT-EVAL software
package.
Remains the question about the reference level of the analyzer, since especially for longdistance transmission lines, this instrument cannot use the same reference voltage potential
as the generator.
The solution is to assume the currently set input range of the analyzing >@9 unit as
reference level. This level equals the m ax. detectable amplitude of all incoming signals (all
higher levels would be clipped), and is represented by the 0dB line on top of Fig. 24.
Consequently, all received signals will be analyzed against 0dB. Applied on the trigger
detection criteria, this means that t he level pattern of an incoming multitone trig ger must be
within a certain range, defined by the trig ger configuration of the analyzer.
Application Hints / Troubleshooting
To execute measurements in the broadcast mode is pr obably one of the more demanding
procedures when working with >@9, mainly because of the remote location between the
generator and analyzer, i.e. the sender and receiver of the multitone burst.
Nevertheless, by considering both the instructions listed in chapter Setup (p. 35) and
following hints, it shouldn’t become a major problem to est ablish a pr operly working set up.
• The most effective approach to successfully execute a first test run, is to place the
sender & receiver not too far apart (e.g. in the same room), however, with both units
already being controlled by individual PCs. Such a setup may probably not include a long
transmission line, but is ideally suited to adj ust t he req uired set ting s of t he major ity of the
involved systems to allow a proper measurement.
• For the first signal transmissions / measurem ents, reduce the num ber of involved stages
to a minimum, to simplify the search f or possible errors. As soon as the first successful
tests are completed, the number of systems in the signal path may be increased
stepwise, and the respective settings may be optimized to the actual demands.
• A very helpful tool to find out possible problems is to use a monitor speaker to make the
transmitted multitone bur st audible at the different stages of the line. Consequently, by
listening to the sound of the burst, the operat or may simply localize critical components
and optimize their transmission behaviour.
The most frequent obstacle in the br oadcast m ode is the ’refusal’ of the analyzer to tr igg er to
the incoming multitone bur st. This effect is usually caused by improper adjustments of the
involved >@9 generator / analyzer, or by sound enhancing instruments (e.g. equalizer,
compressor, limiter, com pander etc.) on the transmission line, which modify the trigger signal
in a way, that it can’t be recognized anymore.
Consequently, the efforts to overcome missing triggerings have to focus on the proper
adjustment of the sending and the receiving >@9, as well as on the mutual optimization
between the trigger signal and the sound enhancing systems.
Possible Cause Effect Suggested Solution
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Generator output level too low
and/or
Analyzer input range too high
The incoming trigger signal level
doesn’t match vs. the analyzer
sensitivity, so that the trigger can’t
be recognized
Increase the generator output
level or decrease the analyzer input range stepwise
Generator output level too high The trigger signal is modified by
sound enhancing units in a way,
that it can’t be recognized any
more by the analyzer
Reduce or attenuate genera-
tor output level
Analyzer input range too low The input stage of the analyzer is too
sensitive, i.e. overloaded, and
therefore can’t recognize the incoming trigger
Increase input range of ana-
lyzer stepwise
Very strong sound enhancing
effects or a low quality of
the transmission line
Distortions, noise or sound enhanc-
ing effects modify the trigger signal in a way, that it can’t be recognized any more by the analyzer
Switch Off all sound enhanc-
ing systems during the
transmission of the multitone burst
Multitone signal not identical
on generator & analyzer
Analyzer triggers correctly, but can’t
acquire a reasonable result
Set the identical signal bins in
the active multitone signal
of the generator & analyzer
Table 8 Broadcast Mode Troubleshooting
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4 PROGRAMMING
Communication via the IEEE-488 interface allows complete remote cont rol for all functions of
>@9.
Command Structure
IEEE-488.1 Compatibility
The IEEE interface function set implemented in >@9. The compatibility level is given in
Table 9
.
Function Implemented Notes
Source handshake SH1 Complete capability
Acceptor handshake AH1 Complete capability
Talker T6 No talk - only mode
Talker (extended) TE0 No capabilit y
Listener L4 No listen-only mode
Listener (extended) LE0 No capability
Service request SR1 Complete capabilit y
Remote local RL0 Only local lockout
Parallel poll PP0 No capability
Device clear DC1 Complete capability
Device trigger DT0 No capability
Controller C0 No capability
Table 9 IEEE 488.1 Compatibility
IEEE-488.2 Commands
>@9 currently does not suppor t all IEEE-488.2 commands. These might be implement ed at
a later state.
Command Summary
Following commands are currently available to control >@9 system. The commands are
divided into four subsystems.
Subsystem Function in RT-1M
SYSTEM Control of RT-1M
INPUT Control of analyzer input section
OUTPUT Control of generator output section
MEASUREMENT Quer y for measurement results
* Device Status
Table 10 Subsystem Definition
Most of the Parameter have to be completed with channel or signal information.
SYSTem:
RESet
MEASurement: LEVel: UNIT
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SYSTem: ERRors? MEASurement: LEVel?
SYSTem: INFormation? MEASurement: DISTortion: UNIT
MEASurement: DISTortion?
INPut: FRONt MEASurement: MTSinad?
INPut: LINK MEASurement: SELectiverss: UNIT
INPut: RANGe MEASurement: SELectiverss?
INPut: SYNC MEASurement: NOISe: UNIT
INPut: SWFilter MEASurement: NOISe?
INPut: DEEMphasis MEASurement: PHASe: UNIT
INPut: TRIGger: ARMed MEASurement: PHASe: SCALe
INPut: TRIGger: ARMed? MEASurement: PHASe?
INPut: TRIGger: BREak MEASurement: CROSstalk: UNIT
INPut: TRIGger: CONFiguration MEASurement: CROSstalk?
INPut: TRIGger: USRConfiguration MEASurement: DTMF: STARt
INPut: TRIGger: USRConfiguration? MEASurement: DTMF?
INPut: STATus?
*STB?
OUTPut: MTONe: PARameter *OPC
OUTPut: MTONe: ACTive *OPC?
OUTPut: LEVel *CLS
OUTPut: BINlevel *ESE
OUTPut: MTONe: PRETriggerlength *ESE?
OUTPut: MTONe: MTONelength *SRE
OUTPut: FLOAT *SRE?
OUTPut: MUTe *ESR?
OUTPut: MTONe: STARt *PSC
OUTPut: MTONe: CONTinuous *PSC?
OUTPut: MTONe: PARameter? *IDN?
OUTPut: MTONe: NAME? *RST
OUTPut: MTONe: BLOCklength? *TST?
OUTPut: MTONe: CRESt? *WAI
OUTPut: STATus?
Descriptive Symbols
Following terms are used in the command description.
Symbol Description
[ ] Used to enclose one or more optional Parameter to control RT-1M. Omitting
the default Parameter causes the system t o use the default action.
{ }
Used to enclose one or more Parameter that may be included several times.
? Indicates a query by appending the question mark to the last keyword in a
command. Not all commands have a query; some are only query comm ands.
¦ Read this signal as an “OR“. It is used to separate alternative Parameter.
< > Used to enclose an SCPI defined parameter
: Used to separate elements of a RT-1M command
; Used to separate commands in a command list
, Used to separate arguments in an arguments list
( ) Used to indicate a range of suffixes available
: →
String is sent from t he cont r o ller t o RT-1M
→ :
Returned string from RT-1M to the controller
Table 11 Symbol Description
>@9 accepts only the short or the exact and full form of the statements. Sending a
command that is neither will generate an error. In following command list, the CAPITAL
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letters indicate the short f orm to help reduce the required typing. However, the >@9 parser
accepts both lowercase and UPPERCASE commands, i.e. it is not case sensitive.
Command Notation
In the listing of >@9 commands, descriptive headings are used to divide the inf ormation into
easily readable parts. The used heading s and the contents are shown below. If a heading
does not apply on a command, it is not listed.
Use
What the command does and additional information is given in the heading.
Answer
Lists the possible answers on a query and their types (integer, float, boolean, string).
Parameter
Description of the Parameter to be set and their types (integer, float, boolean, string).
Range
List of the available Parameter and their types (integer, float, boolean, string).
Default
Description of the default parameter. After a RESET, all Parameter in an instrument are set to
their default values.
Unit
Specification of the available parameter units.
Resolution
Definition the step size of a <Numeric_Value>
Query
Indicates the query command, corresponding to the described command.
Example
Command examples are provided here. The short form and lowercase characters are used as a
reminder that both forms are allowed.
Explanation
Additional explanations and hints.
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Command Set
SYSTem Subsystem
SYSTem:RESet
Use
Initiates a software RESET. All set Parameter in the instrument are re-set to their default
values. Error queue is cleared.
Example
: →
: →
SYST:RES
System:reset
Explanation
The RESET command initializes the complete instrument including the IEEE interface.
Commands, that are in the command buffer, or those which are entered shortly after the
RESET, may be deleted by the RESET command and are therefore not executed.
SYSTem:ERRors?
Use
Queries the number and types of errors since the last Query ¦ Startup ¦ System:Reset
command.
Answer
<Error_No> integer
Range
100 No subsystem separator found (':')
101 No subsystem found
102 No command separator found (':')
110 No SYSTem command found (e.g. RESET)
120 No INPut command found (e.g. LINK)
121 No INPut[1-2] command found (e.g. RANGE)
130 No OUTPut command found (e.g. FLOAT)
131 No OUTPut[1-2] command found (e.g. LEVEL)
132 No MTONe command found (e.g. START)
133 No TRIGger command found (e.g. ARMed)
140 No MEASurement command found (e.g. LEVEL)
141 No MEASurement[1-2] command found (e.g. TDN)
145 No device status command found (e.g. *OPC)
149 TRIGger configuration parameter expected (e.g. LOOSE)
150 No parameter expected
151 Float parameter expected
152 Float parameter out of range (e.g. INP:RANG -5E3)
153 Integer parameter expected
154 Integer parameter out of range
155 String parameter expected (e.g. "ON")
156 "ON" or "OFF" string expected
157 Filter parameter expected (e.g. "CCITT")
158 Location parameter expected (e.g. "FRONT")
159 Sync parameter expected (e.g. "EXTERNAL")
160 String too long
161 Wrong number of samples (512,1024,2048,4096,8192)
162 Corresponding frequency to bin number out of range
163 Phase value out of range
164 Wrong number of MT Parameter
165 IEEE bus error
166 Output buffer overflow
167 Bins must be in increasing order
168 Too many parameter
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169 Integer parameter must be in increasing order
170 Illegal unit
180 Option not installed (e.g. FLOAT)
182 Command not executable during input trigger armed mode
190 Not available in this hardware version
191 Not available with this firmware version
199 Unexpected error occurred – please report to NEUTRIK
200 No parameter in list for start multitone signal in generator
201 No parameter in list referring to received data in analyzer
202 Output 1&2 muted while multitone is started
203 No trigger detected
204 No stereo trigger detected (e.g. for phase measurement)
205 Measurement function needs ≥1 identical bins on both channels
206 Measurement function needs ≥1 different bins on both channels
210 Analyzer overload
220 Battery low (memory backup)
230 Hardware and software revisions do not match
240 Minimum one external measurement required beforehand
246 Measurement not possible – Signal bins defined too close to each other
(chose higher block length o r change signal bins)
250 DTMF receive buffer overflow
255 RS232/GPIB Interface Output Buffer overflow
256 RS232/GPIB Interface Input Buffer overflow
600-716 Please report to NEUTRIK
Example
: →
→ :
: →
→ :
System:Errors?
130,203,204
SYST:ERR?
0
Explanation
If no errors occurred, a "0" is returned. In any other case the list of error numbers in the queue
is returned. All errors are cleared in the instrument after the query.
SYSTem:INFormation?
Use
Query for serial number, hardware revision and firmware version of RT-1M system.
Compatible with SCPI <*IDN?> command.
Answer
<Manufacturer>
<Instrument_type>
<Serial_number>
<Firmware_Revision>
string
string
string (4 digits)
float
Example
: →
→ :
System:Information?
NEUTRIK,RT1M,0456,3.20
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INPut Subsystem
INPut:FRONt [ON¦OFF]
Use
Activates either front or rear panel input connectors (output connectors are always active at
front & rear panel).
Range
OFF ¦ ON boolean
Default
ON (front input connectors are active)
Query
Use command INPut[1-2]:STATus?
Example
: →
Inp:Fron OFF
INPut[1-2]:LINK [OFF¦ON]
Use
Links internally the generator output of RT-1M to the analyzer input. The input connectors of
the selected channel are physically disconnected at front and rear.
Range
OFF ¦ ON boolean
Default
OFF
Query
Use command INPut[1-2]:STATus?
Example
: →
: →
Input2:Link ON
INP1:LINK OFF
Explanation
This command allows e.g. to check the proper operation of RT-1M.
INPut[1-2]:RANGe <Range> <Unit>
Use
Defines the input range & unit for an input channel.
Parameter
<Range>
<Unit>
float
string
Unit
[dBVp ¦ Vp]
Range
-60 to +20 dBVp
0.001 to 10 Vp
(rounded to nearest 0.1dBV)
Default
0 dBVp
Query
Use command INPut[1-2]:STATus?
Example
: →
: →
INPUT1:Range 0 dBVp
Inp2:Rang 0.5 Vp
Explanation
Insert a white space between the value and the unit. The allowed units are peak level units
only, since the Crest factor of the input signa l is unknown.
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INPut:SYNC [INTernal¦INTNoheader¦EXTernal¦EXTNoheader]
Use
Defines the synchronization mode of the instrument.
Range
INT ¦ INTN ¦ EXT ¦ EXTN boolean
INT
INTN
EXT
EXTN
Analyzer sampling clock is derived from the generator crystal. No frequency shift
correction is performed. Use this mode if analyzer and generator are located
together and no frequency shifts are expected. Max. allowable time delay is 1s.
Analyzer sampling clock is derived from the generator crystal. No frequency shift
during transmission must occur. The multitone signal is sent out without any
header. The analyzer expects the multitone signal without trigger and SYNC
block. Use this mode if analyzer and generator are located together but no header
information can be transmitted (e.g. muted measurements) or for analysis of
externally generated signals. Max. allowable time delay is 50ms.
The analyzer clock is synchronized to the frequency of the SYNC block in the
header of the received multitone burst. Frequency shifts are compensated. This
mode is recommended if notable frequency shifts are expected. Max. allowable
time delay is 1s.
No synchronization is transmitted or performed at all. Analyzer clock runs at the
frequency synchronized to the last transmitted multitone burst in Sync Mode
EXT. No further tuning will be performed. Analyzer expects the signal with no
trigger information and generator is set to transmit the multitone signal only. No
major time delay must occur in that mode. This mode requires at least one
measurement in EXT mode before to ensure that the analyzer crystal is tuned.
Default
INT
Query
Use command INPut[1-2]:STATus?
Example
: →
: →
Inp:Sync Internal
INPUT:SYNC INTN
Explanation
Any multitone burst transmission & sampling must be initiated by OUTPut:MTONe:STARt.
INPut:SWFilter [OFF¦CWE¦CCITT]
Use
Activates one of the implemented software weighting filters. Filters are selected for both
channels simultaneously. The filters may be engaged also after the measurements has been
performed. This allows to get first unweighted and afterwards weighted results.
Range
OFF ¦ CWE ¦ CCITT boolean
Default
OFF
Query
Use command INPut[1-2]:STATus?
Example
: →
: →
INPUT:SWFILTER OFF
Inp:SWF CWE
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INPut:DEEMphasis [OFF¦ON]
Use
Activates the 750µs deemphasis, which applies on both channels, regardless of other filters.
Range
OFF ¦ ON boolean
Default
OFF
Query
Use command INPut[1-2]:STATus?
Example
: →
: →
INP:DEEM ON
Input:Deemphasis OFF
INPut:TRIGger:ARMed
Use
Puts RT-1M into the armed mode, where the analyzer waits for an externally generated
incoming multitone burst with trigger.
Query
Use commands INPut:TRIGger:ARMed? and INPut[1-2]:STATus?
Example
: →
Inp:Trigger:Armed
Explanation
This command allows the analyzer to receive multitone bursts that have been generated by
a remote RT-1M unit, i.e. to run the analyzer in the so-called Broadcast Mode.
In the armed status, the Trigger LED will be flashing until a trigger is detected (LED is lit).
Keep in mind that for broadcast applications it is necessary to set the synchronization mode
of the generator / analyzer to INTernal / EXTernal, while the trigger configuration for both
units must be TIGHT (see p. 3-36).
INPut:TRIGger:ARMed?
Use
Queries whether RT-1M is in the armed mode.
Answer
<Trigger_Status>
Range
ARMED ¦ STOPPED string
ARMED
STOPPED
As long as RT-1M is in this mode, it will wait until an incoming multitone
burst is detected or until the unit is re-set into the normal operation.
This status indicates that RT-1M is not armed (i.e. waiting for a trigger),
but in the normal mode. In this status, the Trigger LED will be dark.
Example
: →
→ :
Inp:Trigger:Armed?
ARMED
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INPut:TRIGger:BREak
Use
Disables the armed mode of RT-1M, i.e. re-sets the unit into the normal mode.
Query
Use commands INPut:TRIGger:ARMed? and INPut[1-2]:STATus?
Example
: →
Inp:Trigger:Break
Explanation
This command returns RT-1M into the normal operation, after it has been in the armed
mode.
In the normal mode, the Trigger LED will be dark.
INPut:TRIGger:CONFiguration [LOOSE¦TIGHT¦USER]
Use
Sets the trigger configuration.
Range
LOOSE ¦ TIGHT ¦ USER string
LOOSE
TIGHT
USER
Applies the normal trigger condition on an incoming multitone burst. This
configuration is especially suited for industrial applications, where both
multitone generator and analyzer are located in the same housing.
Applies the tight trigger condition on an incoming multitone burst. This
configuration should be used for broadcast applications, where the signal is
inserted into a shortly interrupted broadcast signal.
This configuration allows the user to define the trigger condition
individually. However, since this requires a highly sophisticated finetuning, it is strongly recommended to be used by very advanced users only.
Default
LOOSE
Query
Use command INPut[1-2]:STATus?
Example
: →
Inp:Trigger:Configuration Tight
Explanation
It is recommended to change the trigger configuration for broadcast operation only, and to
select the TIGHT condition in such cases. As soon as RT -1M is used again for industrial
applications, the trigger configuration should be re-set to LOOSE.
INPut:TRIGger:USRConfiguration
<setbin1(dB)>,<setbin2(dB)>,<emptybin(dB)>
Use
Allows to custom-design the trigger configuration by defining the trigger bins.
Parameter
<setbin(1)>
<setbin(2)>
<emptybin>
integer
integer
integer
Range
<setbin(1)>
<setbin(2)>
<emptybin>
-10 to -50 dB
-10 to -50 dB
0 to -80 dB
Query
Use command INPut:TRIGger:USRConfiguration?
Example
: →
Inp:Trigger:Usrconfiguration -20,-40,-80
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Explanation
This command requires highly sophisticated handling for proper operation!
It shall not be applied as by very advanced users only!
INPut:TRIGger:USRConfiguration?
Use
Queries the defined trigger configuration.
Answer
<setbin1>
<setbin2>
<emptybin>
integer
integer
integer
Range
<setbin1>
<setbin2>
<emptybin>
-10 to -50 dB
-10 to -50 dB
0 to -80 dB
Example
: →
→ :
Inp:Trigger:Usrconfiguration?
-20,-40,-80
Explanation
See chapter Broadcast Mode.
INPut[1-2]:STATus?
Use
Queries the complete input channel status.
Answer
<Range_Unit>
<SW_Filter>
<Front_Conn>
<Link>
<SYNC_Mode>
<Deemphasis>
<Trig_Config>
float & string
boolean
boolean
boolean
boolean
boolean
string
RANGE [-60 to +20 dBVp ¦ 0.001 to 10 Vp]
SWFILTER [OFF ¦ CWEighting ¦ CCIT]
FRONT [OFF ¦ ON]
LINK [OFF ¦ ON]
SYNC [INT ¦ INTN ¦ EXT ¦ EXTN]
DEEMPHASIS [OFF ¦ ON]
TRIGGER [LOOSE ¦ TIGHT ¦ USER]
Example
: →
→ :
: →
→ :
Inp2:Status?
RANGE -3.5000E0 dBVp,SWFILTER CCITT,FRONT OFF,
LINK ON,SYNC INTERNAL,DEEMPHASIS ON,TRIGGER:
CONFIGURATION LOOSE
INPUT1:STAT?
RANGE 1.0000E1 Vp,SWFILTER OFF,FRONT ON,LINK
OFF,SYNC EXTERNAL,DEEMPHASIS ON,TRIGGER:
CONFIGURATION TIGHT
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OUTPut Subsystem
OUTPut:MTONe:PARameter <Parameter>
Use
Defines a multitone signal.
Parameter
<Sig_Number>
<Sig_Name>
<No_Of_Samples>
<No_Of_Bins_CH1>
<No_Of_Bins_CH2>
{<Bin_X_CH1>}
{<Bin_X_CH2>}
{<Phase_X_CH1>}
{<Phase_X_CH2>}
integer
string
integer
integer
integer
integer
integer
float
float
target memory of RT-1M
user-defined signal name
blocklength
total number of bins set in channel 1
total number of bins set in channel 2
bin numbers set in Chn1
bin numbers set in Chn2
phases of bins set in Chn 1
phases of bins set in Chn 2
Range
<Sig_Number>
<Sig_Number>
<No_Of_Samples>
<No_Of_Bins_CH1>
<No_Of_Bins_CH2>
<Bin_No_X_CH1>
<Bin_No_X_CH2>
<Phase_X_CH1>
<Phase_X_CH2>
1 ¦ 2 ¦ 3 ¦ 4
(up to 8 ASCII characters, no spaces allowed)
512 ¦ 1024 ¦ 2048 ¦ 4096 ¦ 8192
1 to 31
1 to 31
Bin_Min
1)
to Bin_Max2)
Bin_Min
1)
to Bin_Max2)
-π to +π
-π to +π
1)
48 000
20Bin Min
Hz
Hz_
’
*=
NoOfSamples
2
48 000
20
)
_
’
*Bin Max
Hz
kHz=
NoOfSamples
Query
Use command OUTPut:MTONe:PARameter?
Example
: →
Output:Mtone:Par
1,’Telefon’,2048,3,3,25,85,256,25,85,256,0,1.5707
,3.14,0,1.5707,3.1415
Explanation
This command defines all compulsory parameter of a new multitone signal.
<No_Of_Bins_CHX> equals the total number of signal bins for channel 1 / 2.
<Bin_No_X_CHY> indicate the bin numbers as calculated with Equation 7 (p. 25).
<Phase_X_CHY> indicate the phases of the signal bins.
OUTPut[1-2]:LEVel <Level> <Unit>
Use
Set the total output level of the multitone signal.
Parameter
<Level>
<Unit>
float
string
Unit
dBVp ¦ Vp ¦ dBV ¦ V
V
dBV
Vp
dBVp
Peak value in logarithmic scale (RMS value is lower by crest factor)
Peak value in linear scale (RMS value is lower by crest factor)
RMS output level in logarithmic scale (peak level is higher by crest factor)
RMS output level in linear scale (peak level is higher by crest factor)
Range
-60 to +20 dBVp
+0.001 to +10 Vp
(rounded to nearest 0.1dBVp)
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Default
0 dBVp
Query
Use command OUTPut[1-2]:STATus?
Example
: →
: →
Outp1:Level -6.2 dBVp
OUTPUT2:LEVEL 3.5 V
Explanation
This command allows to set the output level in either RMS or peak units. The maximum
output level of 10Vp cannot be exceeded..
OUTPut:MTONe:PRETriggerlength <Length>
Use
Definition of the pretrigger duration for the active multitone signal in milliseconds.
Parameter
<Length> float
Range
0 to 30’000
Unit
ms (milliseconds)
Default
0
Query
Not possible.
Example
: →
: →
Output:Mtone:Pret 0
Outp:Mtone:Pretriggerlength 50.5
Explanation
The duration value is rounded to the next possible value. T he duration of the pretrigger
excludes the duration of the trigger, which always occupies some 42ms. The value 0 defines
the shortest possible pretrigger length of 0ms.
The command mainly allows the DUT to stabilize before the multitone signal is transmitted.
OUTPut:MTONe:MTONelength <Length>
Use
Definition of the multitone signal duration for the active multitone signal in milliseconds.
Parameter
<Length> float
Range
0 to 30’000
Unit
ms (milliseconds)
Default
0
Query
Not possible
Example
: →
Output:Mtone:Mton 500
Explanation
The duration value is rounded to the next possible integer multiple of the duration of one
multitone block. The value 0 results in transmission of the min. number of multitone blocks.
The command mainly allows the DUT to stabilize onto the multitone signal before analysis is
started.
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OUTPut[1-2]:BINlevel <Level> <Unit>
Use
Set the bin level of the multitone signal (all bins have equal level).
Parameter
<Level>
<Unit>
float
string
Unit
dBV ¦BV ¦ dBVp ¦ Vp
dBV
V
dBVp
Vp
RMS binlevel in linear scale
RMS binlevel in logarithmic scale
Peak value in linear scale
Peak value in logarithmic scale
Range
-60 to xx dBVp
+0.001 to +yy Vp
(max. binlevel has to be calculated acc. Equation 1 & Equation 6)
Query
Use command OUTPut[1-2]:STATus?
Example
: →
Outp1:Binlevel -6.2 dBVp
Explanation
Be aware that when bin level is set, the total output level is higher as per
Equation 6. The maximum output level of 10Vp cannot be exceeded.
OUTPut[1-2]:MUTe [OFF¦ON]
Use
Mute or unmute a channel output.
Range
OFF ¦ ON boolean
Default
OFF
Query
Use command OUTPut[1-2]:STATus?
Example
: →
: →
Output1:Mute ON
OUTP1:MUT OFF
OUTPut:FLOAT [OFF¦ON]
Use
Sets both output channels to either float or ground mode. In float mode the center tap of the
generator can float to any level. Ground mode is nece ssary for unbalanced outp ut signals.
Range
OFF ¦ ON boolean
Default
OFF
Query
Use command OUTPut[1-2]:STATus?
Example
: →
Output:Float ON
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OUTPut:MTONe:ACTive [1¦2¦3¦4]
Use
Defines the current multitone signal as the active signal used for transmission. All commands
with no signal number refer to the active signal.
Range
1 ¦ 2 ¦ 3 ¦ 4 integer
Default
1
Query
Use command OUTPut[1-2]:STATus?
Example
: →
: →
OUTP:MTON:ACT 2
Output:Mtone:Active 1
OUTPut:MTONe:STARt
Use
Start transmission (i.e. generation & analysis) of the active multitone burst.
Example
: →
OUTP:MTONE:START
Explanation
This command has to be sent either if a multitone burst shall be
• generated and analyzed or
• generated only or
• sampled & analyzed only.
OUTPut:MTONe:CONtinuous
Use
Starts the generator to endlessly send out the active multitone signal.
Example
: →
OUTP:MTONE:CON
Explanation
The signal is sent out in an endless loop. Only the multitone signal is transmitted, i.e. without
header. No measurement may be performed on this signal. This is a generation mode only.
The signal can be stopped by any IEEE command being sent to RT-1M.
OUTPut[1-2]:STATus?
Use
Queries the generator status for channel 1 or channel 2.
Answer
<Active>
<Out_Level>
<BinLevel>
<Mute_State>
<Float_State>
string
string
string
boolean
boolean
ACTIVE [1 ¦ 2 ¦ 3 ¦ 4]
LEVEL [-60 to +20 dBVp ¦ 0.001 to 10 Vp]
BINLEVEL [-60 to xx dBVp ¦ 0.001 to yy Vp]
MUTE [ON ¦ OFF]
FLOAT [ON ¦ OFF]
Resolution
<Out_Level> 0.1dBV
Example
: →
→ :
OUTPUT1:STATUS?
ACTIVE 1,LEVEL -3.5000E0 dBV,BINLEVEL 0.1 V,
MUTE OFF,FLOAT ON
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OUTPut:MTONe:NAME?
Use
Queries the name of the active multitone signal.
Answer
<Name> string
Default
(the active signal name)
Example
: →
→ :
Output:mtone:Name?
Telephon
OUTPut:MTONe:BLOCklength?
Use
Queries the number of samples (i.e. blocklength) of the active multitone signal.
Answer
<Blocklength> integer
Range
512 ¦ 1024 ¦ 2048 ¦ 4096 ¦ 8192
Example
: →
→ :
OUTput:MTONe:BLOCklength
2048
OUTPut:MTONe:PARameter?
Use
Queries the parameter of the active multitone signal. Format is compatible with the command
OUTPut:MTONe:PARameter.
Answer
<Sig_Number>
<Sig_Name>
<No_Samples>
<No_Of_Bins_CH1>
<No_Of_Bins_CH2>
{<Bin_X_CH1>}
{<Bin_X_CH2>}
{<Phase_X_CH1>}
{<Phase_X_CH2>}
integer
string
integer
integer
integer
integer
integer
float
float
1 ¦ 2 ¦ 3 ¦ 4
up to 8 ASCII characters
512 ¦ 1024 ¦ 2048 ¦ 4096 ¦ 8192
1 to 31
1 to 31
Bin_Min to Bin_Max
Bin_Min to Bin_Max
-π to +π
-π to +π
Example
: →
→ :
Output:Mtone:Par?
1,Telefon,2048,3,2,25,85,256,11,102,0.000E+00,1.5
707E+00,3.14150E+00,1.234E+00,0.14170E+00
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OUTPut[1-2]:MTONe:CRESt?
Use
Queries the Crest factor of the active multitone signal.
Answer
<Crestfac> float
Range
(any positive number ≥√2)
Example
: →
→ :
OUTP1:MTONe:CREST?
2.33433E0
Explanation
Refer to chapter Phase / Crest Factor Optimization for further explanations.
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MEASurement Subsystem
MEASurement[1-2]:LEVel:UNIT [dBVp¦Vp¦dBV¦V]
Use
Defines the unit in which the level results shall be expressed.
Range
dBVp ¦ Vp ¦ dBV ¦ V string
Default
dBVp
Example
: →
MEAS1:LEV:UNIT VP
MEASurement[1-2]:LEVel?
Use
Returns the measured signal bin levels of the last received multitone signal for one channel.
Answer
{Set_bin_n}
{Amplitude_n}
integer
float & string
(level value & unit)
Range
Set_Bin_n
Amplitude_n
Bin_Min to Bin_Max (see Equation 4 and Equation 5)
float ¦ NaN & string
Unit
Defined by MEASurement[1-2]:LEVel:UNIT [dBVp¦Vp¦dBV¦V].
Default
NaN (not a number)
Example
: →
→ :
MEAS1:LEV?
3/1.240E0 dBV,23/9.727E-1 dBV,84/8.254E-1 dBV
Explanation
The returned level vector is grouped in result pairs, starting with the first signal bin number, a
"/", the corresponding level value, a white space, and the unit, in which the result is
expressed. Pairs are separated by commas.
If a received level is too low to be measured, ’
NaN’ (not a number) is returned.
MEASurement[1-2]:DISTortion:UNI T [dBV¦V]
Use
Defines the unit in which the distortion result shall be expressed.
Range
dBV ¦ V string
Default
dBV
Example
: →
MEAS1:DIST:UNIT V
MEASurement[1-2]:DISTortion?
Use
Returns the distortion values of all the bands between Bin_Min → Bin_1, Bin_1 → Bin_2,
etc., Bin_n → Bin_Max (see also Distortion).
Answer
Bin_Min
Dist_1
{Set_bin_n}
{Dist_n}
integer
float + string
integer
float + string
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Range
Bin_Min
{Set_Bin_n}
Dist_1,{Dist_n}
Bin_Min
Bin_Min to Bin_Max (see Equation 4 and Equation 5)
float ¦ NaN + string
Unit
Defined in MEASurement[1-2]:DISTortion:UNIT
Example
: →
→ :
Measurement1:Dist?
3/2.23E-2 V,11/8.23E-3 V,27/1.35E-2 V
Explanation
The returned distortion vector starts with the number of the first bin ≥20Hz / the distortion up
to the first signal bin. Second pair is the number of the first signal bin / the distortion result
between this first signal bin and the second signal bin, etc. The last pair is the last signal bin /
the distortion result between this last signal bin and Bin_Max (last bin ≤20kHz; see Fig. 20).
If a band between two signal bins is too narrow to measure a distortion, '
NaN' is returned.
MEASurement[1¦2]:MTSinad?
Use
Returns the SINAD value using the selected Multitone signal in the full bandwidth between
Bin_Min (>20H z) and Bin_Max (< 20kHz). The single va lue calculation considers: Signal
plus Distortion plus Noise to Distortion p lus Noise for any defined multitone signal. (see also
chapter MT-SINAD, p. 30).
Answer
Bin_Max/
MT_Sinad
integer
float ¦ NaN & string
(see Equation 5, p. 19)
(measured MT-SINAD result & unit)
Default
NaN (not a number)
Unit
dB
Example
: →
→ :
Measurement1:MTSinad?
214/5.2235E+01 dB
Explanation
The returned MT-SINAD value considers all signal components, starting with the lowest
possible frequency in the signal at the first bin ≥20Hz up to the highest fr equency bin below
20kHz. It calculates from the distortions and the signal components the single SINAD value.
If a band between two signal bins is too narrow to measure a distortion, the error 246 is
returned.
MEASurement[1-2]:SELectiverss:UNIT [dBV¦V]
Use
Defines the unit in which the RSS (root sum square) selective result shall be expressed.
Range
dBV ¦ V string
Default
dBV
Example
: →
Meas1:Sel:Unit dBV
MEASurement[1-2]:SELectiverss? <binstart> <binstop>
Use
Returns the RSS value for the band from <binstart> to <binstop> (including both levels).
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Parameter
<binstart>, <binstop> integer
Range
Bin_Min to Bin_Max
Units
Defined by
MEASurement[1-2]:SELectiverss:UNIT [dBV¦V].
Default
NaN (not a number)
Example
: →
→ :
MEAS2:SEL? 11 32
32/-1.01352169+02 dBV
(RSS value from Bin #11 to Bin #32,
including levels of Bin # 11 + #32)
Explanation
The RSS selective measurement (see p. 3-30) allows to measure the total distortion + noise
in any frequency band between 20Hz - 20kHz. <binstart> defines the lower border of this
band, while <binstop> defines the upper border of the band.
Please notice, that if the selected band comprises a signal bin, the RSS selective result will
include this signal bin level in addition to the distor tion + noise value of the band.
MEASurement[1-2]:NOISe:UNIT [dBV¦V]
Use
Defines the unit in which the noise measurement results shall be expressed.
Range
dBV ¦ V string
Default
DBV
Example
: →
MEAS1:NOISE:UNIT V
MEASurement[1-2]:NOISe?
Use
Returns the noise values of all the bands between 20Hz → Bin_Min, B in_Min → SigBin_1,
etc., SigBin_n → Bin_Max, Bin_Max → 20kHz (see also chapter Noise).
Answer
Bin_Min
Noise_1
{SigBin_n}
{Noise_n}
Integer
float + string
integer
float + string
Range
Bin_Min
{Set_Bin_n}
Noise_1,{Noise_n}
Bin_Min
Bin_Min to Bin_Max (see Equation 4 and Equation 5)
float ¦ NaN + string
Unit
As defined by command MEASurement[1-2]:NOISe:UNIT [dBV¦V]
Default
NaN (not a number)
Example
: →
→ :
Measurement1:Noise?
3/6.56E-3 V,11/7.32E-3 V,27/6.55E-3 V,
87/5.87E-3 V,2048/4.27E-3 V
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Explanation
The returned noise vector starts with Bin_Min (i.e. the first possible bin ≥20 Hz), followed by
the noise result between this bin and the first signal bin. Second pair is the bin number of the
first signal bin and the noise value between this first signal bin and the second signal bin, etc.
Last pair is the last signal bin with the noise result between the last signal bin and Bin_Max
(i.e. the last possible bin ≤20kHz). See also Fig. 22.
If a band between two signal bins is too narrow to measure noise value, ’
NaN’ is returned.
MEASurement[1-2]:CROSstalk:UNIT [dB¦%]
Use
Defines the unit in which the crosstalk measurement shall be expressed.
Range
dB ¦ % string
Default
%
Example
: →
MEAS1:CROS:UNIT dB
MEASurement[1-2]:CROSstalk?
Use
Returns the measured crosstalk of the last received multitone signal for one channel. The
crosstalk result can be evaluated only if at least one signal bin of each channel is set at an
exclusive frequency.
Default
NaN (not a number)
Example
: →
→ :
MEAS1:CROS?
3/-87 dB,11/-67 dB
Explanation
The returned result pairs indicate the signal bin number, followed by a "/", the corresponding
crosstalk value, a white space, the unit, in which the result is expressed, and a ",".
If the crosstalk value is too small to be measured, '
NaN' (not a number) will be returned.
MEASurement:PHASe:UNIT [rad¦deg]
Use
Defines the unit in which the phase measurement result shall be expressed.
Range
rad ¦ deg string
Default
rad
Example
: →
MEAS:PHASE:UNIT DEG
MEASurement:PHASe:SCALe <Scale>
Use
Defines the lower border of the phase-plot scale, in which the result shall be expressed. The
scale always comprises a full circle, i.e. 2π (rad) or 360° (deg) respectively.
Parameter
<Scale> float
Range
[-2π to 0 ¦ –360 to 0]
Default
0
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Example
: →
: →
MEAS:PHASE:SCALE -180
Meas:Phas:Scal 0
(-180 to +180 deg.)
(0 to +2π rad.)
MEASurement[1-2]:PHASe?
Use
Returns the measured phase-difference between the 2 channels of the last received multitone
signal. The phase value can be calculated only if both channels have recognized a trigger and
if at least one signal bin is identical, i.e. set on both channels.
ATTENTION: In order to get accurate phase values, it is important to set the input
ranges of both channels to the same level.
Answer
{SigBin_1}
{Phase_1}
{SigBin_n}
{Phase_n}
integer
float + string
integer
float + string
Range
{SigBin_n}
{Phase_n}
Bin_Min to Bin_Max (see Equation 4 and Equation 5)
float ¦ NaN + string
Unit
(as defined by command MEASurement:PHASe:UNIT)
Example
: →
→ :
MEAS1:PHASE?
3/1.24E0 deg,23/9.27E-1 deg
Explanation
The returned result is composed of pairs, each starting with the signal bin number, followed
by a "/", the phase result, a white space the unit, in which the phase was measured, and a ",".
MEASurement1:DTMF:STARt
Usage
Resets the DTMF tone receiver buffer (32 keys wide) of channel 1.
NOTE: This command requires installation of the DTMF option for RT-1M.
Examples
: →
Meas1:Dtmf:Start
Explanation
After this command, RT-1M continues to store all incoming DTMF tones in its buffer.
MEASurement1:DTMF?
Usage
Queries the DTMF tone receiver buffer (32 keys wide) of channel 1.
NOTE: This command requires installation of the DTMF option for RT-1M.
Examples
: →
→ :
MEAS1:DTMF?
1/2,2/3,2/2
(3 keys detected: 2,8,5)
Explanation
RT-1M returns pairs of x-/y-coordinates, identifying the DTMF keys in the received order.
The standard 4x4 keypad coding is:
↓
y-coord.
1 2 3 4
→
x-coord.
(unused fields may be user-defined) 1 1 2 3 A
2 4 5 6 B
3 7 8 9 C
4 * 0 # D
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Device Status
*STB?
Use
Fetches the STatus Byte register. See also chapter IEEE Standard Status Data Structure.
Calculation
STB = n7*128 + n6*64 + n5*32 + n4*16 + n3*8 + n2*4 + n1*2 + n0
n7
n
6
n
5
n
4
n
3
n
2
n
1
n
0
Not used
Master summary status (MSS) The MSS message indicates that RT-1M has at
least one reason for requesting service.
Event status summary bit (ESB), indicating whether any of the enabled events
has occurred since the last reading of the standard event status register.
Message available summary bit (MAV). The MAV message indicates whether or
not the output queue is empty. Whenever RT-1M is ready to accept a request by
the controller to output data, MAV summary message will be TRUE.
Not used
Not used
Not used
Not used
Example
: →
→ :
*STB?
32
*OPC
Use
The OPeration Complete command causes RT-1M to generate the operation complete
message in the standard event status register (Bit 0) when all pending selected device
operations have b een finished. The *OPC command allows synchroniza tion between
controller and RT-1M..
Example
: →
*esr?
*ese 1;*sre 32
output:mtone:start, *OPC
(clears previous events)
(enable operation complete event)
(RT-1M will request service [serial poll]
as soon as the measurement is finished)
*OPC?
Use
The OPeration Complete query causes RT-1M to place an ‘1’ into the RT-1M output queue
when all pending selected device operations have been finished. The *OPC command allows
synchronization between controller and RT-1M using the MAV bit in the status byte register.
See also chapter IEEE Standard Status Data Structure.
Parameter
<OPCvalue> boolean
Range
0
1
not finished
finished
Example
: →
→ :
*OPC?
1
Explanation
Use *OPC? with serial polling (e.g. MAV).
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*CLS
Use
The CLear Status command clears status data structures, i.e. standard event status registers, so
that the corresponding summary ESB bit is clear. See also chapter IEEE Standard Status
Data Structure.
Example
: →
*CLS
Explanation
*CLS has same effect as *ESR? query, except it is a command.
*ESE
Use
The standard Event Status Enable command sets the standard event status enable register bits.
The standard event status enable register allows one or more events in the standard event
status register to be reflected in the ESB summary-message bit. See also chapter IEEE
Standard Status Data Structure.
Parameter
<Enable_value> Byte
Range
0 to 255
Example
: →
*ESE 32
(enables command error event)
*ESE?
Use
The standard Event Status Enable query allows the programmer to determine the current
contents of the standard event status enable register. See also chapter IEEE Standard Status
Data Structure.
Parameter
<Enable_value> Byte
Range
0 to 255
Example
: →
→ :
*ESE?
32
*SRE
Use
The Service Request Enable command sets the service request enable register bits. The
service request enabling allows a programmer to select which summary messages in the status
Byte register may cause service request (SRQ). The programmer can select reasons to issue a
service request by altering the contents of the service request enable register. See also chapter
IEEE Standard Status Data Structure.
Parameter
<Enable_value> Byte
Range
0 to 255
Example
: →
*SRE 32
(enables standard event status bit [ESB])
*SRE?
Use
The Service Request Enable query allows to determine the current contents of the service
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request enable register. See also chapter IEEE Standard Status Data Structure.
Parameter
<Enable_value> Byte
Range
0 to 255
Example
: →
→ :
*SRE?
32
*ESR?
Use
The standard Event Status Register query allows the programmer to determine the current
contents of the standard event status register. Reading the standard event status register clears
it. See also chapter IEEE Standard Status Data Structure.
Calculation
ESR = n7*128 +n6*64 + n5*32 + n4*16 + n3*8 + n2*4 + n1*2 + n0
n7
n
6
n
5
n
4
n
3
n
2
n
1
n
0
Power-On event flag, indicating that an Off-to-On power transition has occurred
Not used
Command error event flag, indicating that either a syntax or a semantic error has
been detected. The error-number can be read with the <system:errors?> query
Not used
Device specific error event flag (e.g. no trigger detected). The occurred errornumber can be read with the <system:errors?> query.
Not used
Not used
Operation complete event flag. This event bit is generated in response to the *OPC
command. It indicates that the device has completed all pending operations.
Parameter
<Enable_value> Byte
Range
0 to 255
Example
: →
→ :
*ESR?
32
(command error has occurred)
*PSC
Use
The Power-on Status Clear command controls the automatic power-on clearing of the service
request enable register and the standard event status enable register.
<*PSC 0>
<*PSC 1>
no power-on clearing of the registers.
power-on clearing of the registers and therefore disabling of service request
assertion after power-on
See also chapter IEEE Standard Status Data Structure.
Parameter
<Enable_value> Byte
Range
0 to 1
Default
0
Example
: →
*PSC 0
*PSC?
Use
The Power-on Status Clear query allows the programmer to query RT-1M’s power-on status
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clear flag. See also chapter IEEE Standard Status Data Structure
<*PSC 0>
<*PSC 1>
no power-on clearing of the registers.
power-on clearing of the registers and therefore disabling of service request
assertion after power-on
Parameter
<Power_on_flag> Byte
Range
0
1
not cleared
cleared
Example
: →
→ :
*PSC?
0
*IDN?
Use
The IDentificatioN query gets the unique identification of RT-1M. See also chapter IEEE
Standard Status Data Structure.
Parameter
<Manufacturer>
<Instrument_type>
<Serial_number>
<Firmware_revision>
string
string
string [4]
float
Example
: →
→ :
*IDN?
NEUTRIK,RT1M,0122,3.01
*RST
Use
The ReSeT command performs a device reset. All Parameter are set to default values except
the output- and command-queue. See also chapter IEEE Standard Status Data Structure.
Parameter
No Parameter
Example
: →
*RST
*TST?
Use
The self-TeST query causes an internal self-test and places a response into the output queue
indicating whether or not RT-1M completed the self-test without errors.
Parameter
<Self_test> Byte
Range
0
1
errors occurred
self test OK
Example
: →
→ :
*TST?
1
*WAI
Use
The WAIt-to-continue command prevents RT-1M from executing any further commands or
queries until the no-operation pending flag is TRUE. However, since RT-1M has
implemented only sequential command execution, the no-operation command flag is always
TRUE.
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Example
: →
*WAI
Examples
Use of an *OPC command
The *OPC and *WAI commands and the *OPC? query allow the controller to synchronize
itself to the end of a calculation per formed by >@9.
: →
*esr?
*sre 32;*ese 1
(clears previous events)
(enable operation complete event)
output:mtone:par
1,’telephon’,8192,3,3,600,1000,3000,
630,970,3030,0,0,0,0,0,0,*opc
→ :
(as soon as the calculation is finished,
RT-1M requests service [SRQ] by serially
polling the controller)
Use of MAV bit in the status Byte register
: →
*sre 16
(enable Output queue Not-empty event)
output:mtone:start
(start measurement)
meas1:dist?
(get distortion values)
→ :
(as soon as the output queue has the valid distortion results, RT-
1M requests service [SRQ] via serial poll)
As soon as e.g. a *SRE 16 has been sent to the unit, >@9 is set to the service request
mode. This means that >@9 will send back a service request t o the PC each time t hat it has
a new message (e.g. measurement r esult ) ready.
However, please notice that this message may be transferred to the PC by serial polling
only, since >@9 cannot add any further informat ion t o t he ser vice request.
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IEEE Standard Status Data Structure
76543210
7 6 ESB MAV 3 2 1 0
76543210
7 54321
0
&
&
&
&
&
&
&
&
&
&
&
&
&
&
&
Logical OR
Logical OR
Standard
Event Status Register
*ESR?
Status By t e Register
read by *STB?
read by Serial Poll
Standard
Event Status
Enable Register
*ESE <NRf>
*ESE?
Service Request
Enable Register
*SRE <NRf>
*SRE?
Power ON
Not Used
Command Error
Not Used
Device Dependent Error
Not Used
Not Used
Operation Complete
RQS
MSS
Service
Request
Generation
1)
Queue
Not-Empty
Output Queue
For more detailed information refer to IEEE Std 488.2-1992 (IEEE Standard Codes,
Formats, Protocols, and Common Com m ands).
1)
Service Request clears RQS but not MSS!
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5 APPLICATION HINTS
>@9 is ideally suited to be integrated into industrial environments, having virtually no
switches and buttons. All control is established through IEEE commands, allowing to
introduce Audio tests as a standard part of the entire QC procedure.
Arbitrary Generator
With it s flexibility, ease of operation and its excellent price/perfor mance ratio, >@9 can be
used as a simple arbitrary generator. T his way, after f ew minutes of prog ramming only, >@9
can serve as a sine wave generator with one fixed, extremely stable frequency or as an IMD,
DFD or W&F generator with two frequencies defined. The four dual channel memory
locations also allow to have all these configurations permanently stored.
Alignment and Adjustments for Audio Repair Facilities
With the abilit y to plot two to three f req uency responses every second, alignment sequences
for tapes, where they have to be done manually, or bias adjustm ents of amplifiers can be
speeded up. Repeated phase measurements simplify the alig nment of the azimuth angle of
the playback head of a tape recorder - a procedure that normally has to be repetitively
performed for low-, mid- and high frequencies.
Cellular Phone Testing
Increasing production volume, based on the fast growth of cellular networks and coupled
with the requirement for 100% testing of the units, makes an improvement at production
bottleneck - the audio analysis - necessary. >@9 is ideally suit ed to serve as a high-speed
audio analyzer for production testing. The LF- output signal of the system may be RFmodulated and transmitted through an antenna, to quickly obtain the frequency response
and distortion in the voice band of the whole signal path. Frequency shifts as they may
appear on AM/FM transmissions are eliminated by the synchronization capabilities of >@9.
SINAD measurements with a single bin stimulus are possible down to a value of 1dB. The
trigger detection works reliably if the signal is transmitted on the second channel, too.
The dual channel capabilities of >@9 even makes it possible to perf or m tr ansmit and r eceive
testing simultaneously. One channel g enerates the source signal for the transm itter path of
the phone (Mic input), while an external test demodulator feeds back the signal to the
analyzer of the same channel. The output of the second channel is fed into an external
modulator, that supplies the RF signal for the receiver path of the phone. The phone
demodulates the signal and the feeds into t he second analyzer channel of >@9.
Rub & Buzz Speaker Testing
The multitone featur e of >@9 is ideally suited for Rub & Buzz speaker test ing in production
lines. Most frequently seen defects of speakers are mechanical friction of the moving coil
and the magnet, as well as excentrical alignments leading to a staggering movement of the
coil. In any of these cases, the speak er either starts t o produce nonlinear distortion or adds
additional signal energy to frequencies not being part of the original signal. Both of these
effects can be measured in a fraction of a second. Harmonics and new frequencies will
appear in the distortion-, and in most cases in the noise-plot.
Anyway, the stimulation of a speaker with a multitone signal is more realistic and comes
closer to real-world signals. Actually, the mentioned effects may remain unnoticed when
stimulating with a single freq uency only.
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RT-EVAL Software Package
In order to simplify the operation of >@9 especially for new users, an easy-to-understand
evaluation package has been released. This versatile tool pr ovides not only access to almost
all available features of the unit, but also extends this range by some very useful functions
like a Crest factor optimizer etc.
Fig. 25 RT-EVAL Screenshot
Fig. 25 shows a typical screen shot of the RT-EVAL software with generator, analyzer,
multitone, system configur at ion & m easur ement panel.
Please contact you local representative to get a free copy of this package.
Units & Conversion
Especially in the field of telecommunicat ion, there exists a large number of different unit s to
express a level value, while for practical reasons, >@9 provides a restr icted number of these
units only.
The subsequent table lists the most common units and provides the necessary conversion
formulas and examples for a better understanding.
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Unit Explanation Conversion Formula Examples
dB
Decibel - unit of measure of relative voltag e
level
dB
V
V
= 20
10
1
2
*log ( )
dBV
RMS Voltage in dB referred to 1[V
RMS
]
dBV
V
RMS
= 20
1
10
*log (
[]
)
V
RMS
020
1
1
10
dBV = *log (
[]
[]
)
V
V
RMS
RMS
dBVp
Peak Voltage in dB referred to 1[ V
Peak
]
dBVp
V
Peak
= 20
1
10
*log (
[]
)
V
Peak
020
1
1
10
dBVp = *log (
[]
[
)
V
V]
Peak
Peak
dBm
Power in relative to 1[mW]. Please notice, that
every dBm result refers to the actual input
impedance, as e.g. 600Ω.
dBm
V
WR
RMS
In
= 20
0001
10
*log (
.[]*[]
)
Ω
222 20
1
10
.*log(
[]
)dBm =
V
0.001[W]*600[ ]
RMS
Ω
dBm0
dBm referred to or measured at a point of zero
transmission level.
dBrn
dB above reference noise. Weig hted circuit
noise power in dB referred to 1pW @
600[Ω]which is defined as 0dBrn (-90dBm).
Type of weighting is indicated by next letter
(see dBrnc).
dBrn
V
WR
RMS
In
=−20
1
10
12
*log (
[]* [])Ω
020
0000025
10
dBrn = *log (
.[]
)
V
1 [W]*600[ ]
RMS
-12
Ω
dBrnc
Weighted circuit noise power in dBrn ,
measured on a line by measuring set with ’C’
message weighting.
dBrnc0
Noise measured in dBrnc referred to zero
transmission level point (0TLP).
dBrnc0 dBrnc
R
Load
=−20
600
10
*log (
[])Ω
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6 SPECIFICATIONS
Generator
Number of channels
2
Generator type
multitone arbitrary
Resolution
16bit
Sampling rate
48kHz
Frequency resolution
5.86Hz @ blocklength 8192
Number of signal memories
4 (stereo)
Number of test signal frequencies
1 to 31
Signal Frequencies
20Hz to 20kHz
Multitone burst duration
260ms to 960ms depending on frequency resolution
max. up to 30sec or continuous (programmable)
Residual distortion
< -86dB or 10µV
Output Level Symmetric
-60 to +20 dBVp in 0.1dB steps (for each channel individually)
Level accuracy
< 0.2dB (@ 1kHz)
Flatness
< 0.2dB (20Hz to 20kHz)
Analyzer
Measurement functions
Level, Total Distortion, Noise, Interchannel Phase, Crosstalk
(measured simultaneously)
Number of channels
2
Resolution
18bit
Sampling rate
48kHz
Residual distortion
< -86dB (input signal > -15dBVp)
Frequency resolution
2.95Hz minimum
Input Range (bal.)
-60 to +20 dBVp
Level accuracy
< 0.2dB (@ 1kHz)
Flatness
< 0.2dB (20Hz to 20kHz)
Synchronization
Internal or External
Measurement turn around time
800ms @ blocklength 512 and 3 signal bins
General
Dimensions
483 x 318 x 44 mm (19“ x 12.5“ x 1.75“ - 1 rack unit high)
Weight
7kg
Remote control
IEEE-488
Power requirements
100/120/230V, 50/60Hz, 60VA
Calibration
1 year recommend calibration interval
Operating temperature
5°C to 45°C (40 to 110F) with R.H. < 90% non condensing
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7 INDEX
A
AC Power Connection..........................11
Accessories.........................................10
Address Selection................................12
Analyzer
Block Diagram .........................................23
Filters.......................................................23
Application Hints......................10, 37, 66
B
Balanced Connection.....................12, 13
Battery Low.......................................... 13
Bin
Amplitude.................................................25
Number....................................................25
Types.......................................................19
Blocklength....................................18, 20
BNC Cables.........................................13
Broadcast Mode...................................35
Burst Duration......................................20
C
Calculating LED Indicator.....................14
CE Conformity.......................................4
Cellular Phone Testing.........................66
Command
Notation....................................................41
Communication......................................9
Comparability of MT Signals................20
Connection
Balanced..................................................12
Unbalanced..............................................12
Conversion of Units..............................67
Crest Factor...................................17, 19
Crosstalk Measurement.......................33
D
dB & Related Units...............................68
Descriptive Symbols ............................40
Distortion
Full Band..................................................30
Measurement...........................................28
Plot...........................................................29
Driver Library....................................... 10
DTMF Mode.........................................34
Duration
of Multitone Burst.....................................20
of Multitone Signal ...................................18
E
Error LED Indicator.............................. 14
Evaluation Software.............................10
Even Bins............................................19
EXTernal.............................................27
EXTNoheader......................................27
F
FFT .....................................................17
Filtering...............................................23
Frequency Response .......................... 28
Frequency Spacing .............................18
Full Band............................................. 30
Noise Measurement................................ 32
TD+N Measurement................................ 30
THD+N Measurement............................. 30
Function Test ......................................15
G
Generator............................................ 22
Analog Section........................................ 22
Block Diagram......................................... 22
Digital Section ......................................... 22
Signal Definition ...................................... 24
GPIB Board......................................... 10
Grounding ...........................................13
H
Header ................................................ 25
HT BASIC............................................ 15
I
IEEE
Address Selection ................................... 12
Compatibility............................................ 39
Connection.............................................. 12
Status Data Structure.............................. 65
Installation........................................... 11
Interface LED Indicator........................ 14
INTernal.............................................. 26
INTNoheader....................................... 27
L
LED Indicators.....................................14
Level Measurement.............................28
LOOSE Trigger ................................... 36
Low Battery Indicator........................... 13
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M
Mains Cable.........................................12
Microphones........................................10
MT-SINAD........................................... 30
Multitone
Background..............................................16
Burst Structure.........................................24
Parameter................................................17
Signal.......................................................26
N
Noise
Full Band Measurement...........................32
Noise Measurement.............................32
O
Odd Bins..............................................19
Options................................................10
Overload LED Indicator........................ 14
Overview................................................9
P
Phantom Power Supply........................10
Phase ..................................................19
Phase Measurement............................34
Power LED Indicator............................14
Program Example................................15
Programming.......................................39
R
Rack Mount..........................................11
RMS Value...........................................29
RSS
Selective Measurement ...........................31
Value........................................................29
RT-EVAL .............................................67
Rub & Buzz Testing.............................66
S
Sampling Rate.....................................17
Signal
Bins ......................................................... 19
Definition ................................................. 24
SINAD.................................................30
Software Tools....................................10
Speaker Testing..................................66
Specifications......................................69
SYNC Block.........................................26
Synchronization
Frequency ............................................... 26
Mode ....................................................... 26
System Description..............................16
T
TD+N
Full Band Measurement.......................... 30
TD+N Value.........................................28
Test of Function ..................................15
THD+N Calculation..............................30
TIGHT Trigger.....................................36
Trigger........................................... 25, 26
Configuration........................................... 36
LED Indicator........................................... 14
U
Unbalanced Signals.............................12
Units....................................................67
Unpacking...........................................11
USER Trigger...................................... 36
V
Voltage selector...................................11
W
WARRANTY.............................................3
X
XTALK................................................. 33
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