Rohde & Schwarz UPD Installation and operating instructions

Loudspeaker measurements
with Audio Analyzers
UPD or UPL
Application Note 1GA16_1L
replaces 1GPAN16L Subject to change
M. Schlechter 07.97
Products:
Audio Analyzer UPD
Audio Analyzer UPL

1GA16_1L.DOC ROHDE & SCHWARZ1
Content
1 INTRODUCTION 3
2 PREPARATIONS 3
2.1 HARDWARE AND SOFTWARE REQUIREMENTS 3
2.2 SOFTWARE INSTALLATION 4
2.3 STARTING THE APPLICATION SOFTWARE 4
2.4 CONFIGURING THE APPLICATION 4
2.4.1 SETUP AND CONFIGURATION FILES 5
2.4.2 PRELIMINARY CONFIGURATION OF SETUP FILE 5
2.5 CONVERTING THE SETUP FOR SOFTWARE UPDATES 6
3 OPERATING CONCEPT 6
3.1 OVERVIEW 7
3.2 SOFTKEY LEVELS 7
3.3 SOFTKEYS COMMON TO ALL LEVELS 7
3.4 ENTRY OF PARAMETERS 7
3.5 COMMON SOFTKEYS FOR POST-PROCESSING 8
4 MEASUREMENT MODES 9
4.1 MODES OF FREQUENCY RESPONSE ANALYSIS 9
4.2 FREQUENCY SWEEP 10
4.2.1 ADVANTAGES 10
4.2.2 SETUP AND PROGRAM SETTINGS 10
4.3 FFT NOISE 10
4.3.1 ADVANTAGES, LIMITS AND MAIN FIELDS OF APPLICATION 11
4.3.2 SETUP AND PROGRAM SETTINGS 11
4.4 SWEPT BURST MEASUREMENT 12
4.4.1 ADVANTAGES AND MAIN FIELDS OF APPLICATION 12
4.4.2 PROGRAM SETTINGS 12
4.5 GO/NOGO TESTS 12
4.6 SELECTING THE MEASUREMENT MODE 13
5 MEASUREMENTS 13
5.1 IMPEDANCE AND ASSOCIATED PARAMETERS 14
5.1.1 TEST SETUP 14
5.1.2 SPECIAL NOTES ON ENTRY OF PARAMETERS 15
5.1.3 DC IMPEDANCE 15
5.1.4 IMPEDANCE FREQUENCY RESPONSE 16
5.1.5 RESONANCE FREQUENCY AND RESONANCE IMPEDANCE 17
5.1.6 ABSOLUTE MINIMUM AND MAXIMUM IMPEDANCE 17
5.1.7 TUNING FREQUENCY 17

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5.1.8 Q FACTOR 18
5.1.9 EQUIVALENT VOLUME 18
5.1.10 GO/NOGO TEST 19
5.2 SOUND PRESSURE MEASUREMENTS 19
5.2.1 TEST SETUP 19
5.2.2 ADJUSTING THE OUTPUT POWER 21
5.2.3 ENTRY OF MICROPHONE AND ROOM PARAMETERS 22
5.2.4 SELECTING THE SOUND PRESSURE UNIT 22
5.2.5 SENSITIVITY MEASUREMENT AND RADIATION ANGLE 23
5.2.6 FREQUENCY RESPONSE OF SOUND PRESSURE LEVEL AND TRANSMISSION RANGE 24
5.2.7 SELECTING THE COMBINED NEAR/FAR-FIELD MEASUREMENT 26
5.3 PHASE AND ASSOCIATED PARAMETERS 27
5.3.1 TEST SETUP 27
5.3.2 FREQUENCY RESPONSE OF PHASE 28
5.3.3 LINEARITY DEPARTURE AND GROUP DELAY 29
5.4 POLARITY 30
5.4.1 MEASUREMENT FUNCTION POLARITY FOR ELECTRICAL SYSTEMS 30
5.4.2 POLARITY CHECK BY COMPARISON TO REFERENCE PHASE MEASUREMENT 30
5.4.3 POLARITY CHECK BY COMPARISON TO REFERENCE SOUND PRESSURE CHARACTERISTIC 31
5.5 DISTORTION 32
5.5.1 SPECIAL FEATURES OF THD+N MEASUREMENT (WITH POST-FFT) 33
5.5.2 SPECIAL FEATURES OF ZOOM FFT 33
6 COMBINING SEVERAL MEASUREMENTS 33
6.1 MACRO OPERATION 34
6.1.1 RECORDING A MACRO 34
6.1.2 RUNNING A MACRO 34
6.1.3 PREDEFINED MACROS 35
6.2 CREATING AND USING DIFFERENT CONFIGURATION FILES 36
6.3 LABELLING OF MACRO AND CONFIGURATION MEMORY LOCATIONS 36
7 PROCESSING OF MEASUREMENTS 38
7.1 CHANGE OF TASK APPLICATION/USER INTERFACE 38
7.2 PRINTOUT 38
7.2.1 PRINTOUT AT USER INTERFACE 39
7.2.2 PRINTOUT DURING RUNNING APPLICATION 39
7.3 RESTART 39
7.3.1 RESTARTING A MEASUREMENT 39
7.3.2 RESTARTING THE APPLICATION 39
8 TERMINATING THE APPLICATION 39
11

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1 Introduction1 Introduction
Audio Analyzers UPD and UPL with their large variety of functions provide practically all measurement
procedures required in audio technology. Thanks to the Universal Sequence Controllers UPD-K1 and
UPL-B10, which are available as options, the user is able to considerably expand the range of functions to
suit his particular requirements. It is possible, for instance, to add complete measurement functions - eg
measurement of ohmic resistance - and to read out, convert or reload sweep results or to add new scale
labelling (eg group delay). Another example is the analysis of sweep curves and the display of results in a
window next to the curve. As far as softkey labelling and functions are concerned, operation of the
sequence control programs is analogous to the softkey control of the UPD/UPL graphics display.
This application contains a BASIC program permitting automatic measurements of loudspeaker
parameters with the aid of the features described above. The program can be run on UPD with UPD-K1
and on UPL with UPL-B10. The application software supports the following measurements or
measurement sequences:
• Measurement of impedance characteristic with calculation of tuning frequency, resonance frequency
and resonance impedance, DC resistance, minimum and maximum impedance, Q factor and
equivalent volume.
• Measurement of sound characteristic with calculation of transmission range as well as measurement
of sensitivity and peak sound pressure.
• Measurement of intermodulation products at fixed frequencies or of harmonic distortion as a function
of frequency using a variety of measurement procedures and displays
• Measurement of phase linearity and group delay as well as
• Various methods for checking the polarity
The software not only yields highly accurate results for the development of loudspeakers but also
supports measurements in production testing:
• Impedance- and frequency-response curves can be referenced to a "golden unit" so that a GO/NOGO
decision can be made for each tested device.
• Control of measurement sequences can be stored (learned) by the program so that whole sequences
can be performed by a keystroke without any further intervention being required. Thus several
measurements can be combined to a series of measurements (macro operation).
The measurements and calculations described in this Application Note are in line with DIN IEC 268,
part 5.
22 PreparationsPreparations
22.1.1 Hardware and Software RequirementsHardware and Software Requirements
The accompanying floppy disk holds BASIC program modules and one complete setup (SPEAKER.SCO),
so that the application software can be run immediately under the UPD/UPL universal sequence controller
(UPD-K1 or UPL-B10). As regards the hardware, an UPD/UPL of basic configuration will be sufficient. An
external keyboard is required for operating the automatic sequence controller.
The following software requirements must be met:
• UPD software version 3.03 or higher, UPL software version 1.01 or higher,
• Universal Sequence Controller UPD-K1 or UPL-B10,
• configuration 3 (64-Kbyte program and 32-Kbyte data memory), for very long sweeps (more than 400
sampling points) or combined near/far-field measurements possibly configuration 5 (64-Kbyte data
memory).
Note: UPD and UPL are configured with the aid of service programs UPDSET and UPLSET,
respectively.

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22.2.2 Software InstallationSoftware Installation
Same as the UPD/UPL software, the application software is installed with the aid of the installation
program APPINST.BAT:
• quit UPD/UPL (press SYSTEM key or Ctrl F9,
• insert the supplied floppy disk,
• select floppy disk drive (A:),
• call up the installation program (APPINST).
The installation program creates a subdirectory with the name SPEAKER (if not yet available) and then
copies the BASIC program modules and setups required for the application into this subdirectory.
After the installation, the SPEAKER.SCO setup can be adapted to specific user requirements and to the
external hardware (printer, monitor). See also section 2.4.2, Preliminary Configuration of Setup File.
22.3.3 Starting the Application SoftwareStarting the Application Software
The application software is loaded and started under the universal sequence controller. So the device
software has to be started first (either by switching the instrument on or by calling up the UPD/UPL at
DOS level) and then the universal sequence controller is selected with key F3 (external keyboard).
Note: Before selecting the universal sequence controller make sure that the logging mode is switched
off ("logging off" displayed at the very right of the command line) as otherwise commands
entered in the manual mode are added to the application program and this might cause the
BASIC program memory to overflow. The logging mode is switched on and off by means of key
F2.
The application software must be started from the path
⇒ \SPEAKER
as it searches for all program modules in the current path. Therefore, either the path has to be changed or
the application setup \SPEAKER\SPEAKER.SCO be loaded.
The path can be changed in one of the following ways:
• in the device software under "Working Dir" in the FILE panel
• in the automatic sequence controller with the BASIC command line
⇒ UPD OUT "MMEM:CDIR '\SPEAKER'".
Note: UPL OUT and UPD OUT are synonymous, the BASIC program always uses UPD OUT.
• at the DOS level with CHDIR (via the SHELL of the automatic sequence controller)
The BASIC program SPK.BAS can now be loaded and started. To do so the following entries have to be
made:
• press the LOAD softkey,
• enter SPK (confirm with "return"),
• press the RUN softkey.

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22.4.4 Configuring the ApplicationConfiguring the Application
2.4.1 Setup and Configuration Files
The application software uses two different sources for device setting:
SPEAKER.CFG: Configuration file holding all user entries (see section 3.4, Entry of Parameters) or
default values on initial call-up. When the application is started, this file is loaded; when the application
is left using the EXIT softkey (see section 7, Terminating the Application) the file is stored with updated
values so that the entries made by the user during the last run are reinstated on starting the application
again. If as an exception user entries should not be stored, the application should be quit with CTRL
BREAK.
SPEAKER.SCO: Setup file used as the basis for all commands of the application software. Most of the
settings in this file have to remain unchanged or are overwritten by the application software. A few
settings only may be (or have to be) updated by the user. The program reads the setup but does not
change it. The final version of the setup may be protected against inadvertent overwriting by assigning
the attribute READ ONLY.
Note: Alternative configuration files can be stored and loaded under the menu item UTILITY ->
CONFIG. This capability is particularly important when macros are used (see section 6,
Combining Several Measurements).
The SPEAKER.SCO setup also includes settings that are identical for all procedures and measurements:
FIG 1: Generator, analyzer and display panel of SPEAKER.SCO setup

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2.4.2 Preliminary Configuration of Setup File
The following modifications of the SPEAKER.SCO setup file are permissible:
• selection of printer interface (SCREEN HARD COPY in OPTIONS panel),
• defining a maximum generator voltage for protecting DUTs,
• driving an external monitor (Extrn Disp in OPTIONS panel),
• changing the X axis from log to linear (Spacing LIN POINTS in GENERATOR panel and X-AXIS-
>Spacing LIN in DISPLAY panel),
• changing the Y1 axis from lin to log (TRACE A->Spacing LOG in DISPLAY panel), applies to
impedance measurements only,
• selection of commands to be displayed in the status panel ("tick off"),
• comments in plain text in the graphics display (DISPLAY panel) and info text (FILE panel)
• comments in plain text for printout (dialog box of hardkey HCOPY),
• defining tolerance curves/values and checks (LIMIT CHECK in DISPLAY panel).
The application software is tailored to the audio range, ie to the 25-kHz generator and a 22-kHz analyzer.
In the UPD instruments for higher frequencies may also be selected but in this case the following aspects
have to be considered:
• the lower limit frequency of the analyzer is higher,
• the resolution of the 8k FFT is only 41.67 Hz (100-kHz analyzer) or 125 Hz (300-kHz analyzer),
• the measurement speed is lower.
With the preliminary configuration terminated, the setup has to be stored (as complete setup) under the
same name and may be assigned the attribute READ ONLY.
IMPORTANT: Only the listed settings may be modified, as otherwise proper function of the software
cannot be guaranteed.
22.5.5 Converting the Setup for Software UpdatesConverting the Setup for Software Updates
If the device software is updated, the SPEAKER.SCO - and all other setups - may require to be
converted. This is done automatically when the setup is loaded but to avoid unnecessary delays during
loading, SPEAKER.SCO should be stored as converted setup. This can be done in two ways:
• at the DOS level by calling up the batch converter:
⇒ UPD_CONV \SPEAKER\SPEAKER.SCO or
⇒ UPL_CONV \SPEAKER\SPEAKER.SCO,
• at the UPD/UPL level by loading and storing SPEAKER.SCO.
IMPORTANT: with setups set to READ ONLY, the "r" attribute has to be deleted at the DOS level:
⇒ ATTRIB -r \SPEAKER\SPEAKER.SCO

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33 Operating ConceptOperating Concept
33.1.1 OverviewOverview
The application is operated by means of softkeys which are organized in 4 hierarchical levels. When the
application software is started, the first (highest) softkey level is displayed; pressing a softkey triggers an
action and/or causes another softkey level to be entered. Each level may have up to eight active softkeys;
unassigned softkeys are blank. Same as in the UPD/UPL device software, function keys F5 to F12
correspond to softkeys #1 to #8.
Each time a softkey is pressed, the displayed softkey are cleared. No entries can be made while the
application program carries out setting sequences or calculations or waits for the end of a measurement.
The softkeys are blank. Only after the softkeys have been assigned new (application) functions can
further entries be made.
33.2.2 Softkey LevelsSoftkey Levels
Functions of the four hierarchical softkey levels:
• Level 1 (main level): selection of measurement; implicit loading of a specific measurement module
• Level 2: selection of measurement mode (frequency sweep or FFT noise; see section 4, Measurement
Modes) with implicit (re)-loading of SPEAKER.SCO setup;
• Level 3: entry of parameters and start of measurement;
• Level 4: post-processing and restart of measurement.
DRUN
EXIT
BACK
BACK
BACK START
START
(RE)ZOOMGOTOUPDHARDCOPY
IMPEDANCSOUNDPHASE
FFT RANDFRQSWP
VOLTAGEFREQRNGSWPPNTS
Veq/Vb
RUNAWAYS
THD
D
FIG 2: Operation of application software via softkey menus
33.3.3 Softkeys Common to all LevelsSoftkeys Common to all Levels
Two of the altogether eight softkeys are assigned the same function at all levels and are always located at
the same position:
• the lefthand softkey (#1, F5) is used for returning to the next higher level (BACK); at the top level the
application is quit (EXIT; see section 7, Terminating the Application),
• the righthand softkey (#8, F12) is only active at levels 3 and 4 and used for starting the measurement;
at the end of the measurement the application is always at level 4.

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33.4.4 Entry of ParametersEntry of Parameters
All parameters are entered at level 3 and initiated by softkeys. Strings, integer and floating-point numbers
are entered in a dialog, a 1-out-of-N selection is made at another softkey level.
For dialog entries the following applies:
• The designation of the parameter (eg voltage) is displayed in the entry line, possibly together with the
unit (eg V).
• The currently set value is displayed at the right of the cursor. It may be overwritten or confirmed by
means of the RETURN key.
• Floating-point numbers are entered in the specified unit; only the value is entered.
• If the permissible upper or lower limit is exceeded, the entry is limited to this value or a new entry is
requested.
For 1-out-of-N entries the following applies:
• Selecting a 1-out-of-N entry opens up a 1-out-of-N selection level at which selectable values are
assigned to the softkeys.
• When the desired softkey is pressed the selected value becomes valid immediately and the 1-out-of-N
selection level is closed.
Since the parameters to be entered in this way are the same for most of the measurements, they will be
explained in brief below. Special parameters shall be dealt with together with the respective
measurement. The mentioned measurement modes FFT noise and frequency sweep are explained in
detail in section 4.
- VOLTAGE (F6, level 3): total voltage (FFT noise) or sinewave voltage (frequency sweep), at the same
time DC voltage for measuring the DC resistance.
- FREQ RNG (F7, level 3): Lower Freq (in Hz) and Upper Freq (in Hz): frequency range within which
sinusoidal lines are generated (FFT noise) or sweep points set (frequency sweep). With FFT noise
mode, reducing the frequency range also reduces the number of sinusoidal lines and therefore
shortens the time required for generating the noise signal. If frequency sweep is used the resolution is
improved (constant number of sweep points).
- SWP PNTS (F8, level 3): number of sweep points (frequency sweep only). Reducing the sweep points
shortens the sweep time, an increase improves the resolution.
- FFT SIZE: number of FFT lines determining the FFT resolution and therefore the FFT noise. Reducing
the lines causes the resolution to deteriorate but shortens the time for generating the noise signal and
the FFT measurement time.
33.5.5 Common Softkeys for Post-ProcessingCommon Softkeys for Post-Processing
The softkeys for post-processing are at softkey level 4. Some of them are available for all measurements
and always assigned the same function (and label):
• Softkey #2 (F6): o <--> O changes from partial to full graphics display and vice versa.
• Softkey #3 (F7): GOTO UPD changes temporarily to the UPD operating software (see section 7.1,
Change of Task Application/User Interface)
• Softkey #4 (F8): HARDCOPY outputs the screen content to a printer or file (see section 7.2.2, Printout
during Application Run)

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44 Measurement ModesMeasurement Modes
44.1.1 Modes of Frequency Response AnalysisModes of Frequency Response Analysis
Measuring the frequency response of various parameters is particularly important in development and
production testing. Such parameters are for instance:
• electrical transfer function of crossover units,
• acoustic transfer function of loudspeakers,
• impedance characteristic,
• sound pressure characteristic,
• phase characteristic and group delay,
• distortion.
These parameters can be measured by the frequency sweep of a sinewave signal and displayed in a
tabulated or graphical form. Each curve may contain of up to 1024 single measurements with linear or
logarithmic scaling as required.
Frequency sweeps are very time-consuming because of the generator setting time, DUT settling time,
measurement time and, for acoustic measurements, the signal travel time involved. Particularly at low
frequencies, settling time and measurement time may be too long when it comes to alignments or
production testing.
All measurements based on voltage measurements may also be carried out with a noise generator and an
FFT analyzer. The (quasi)-noise generator of the UPD/UPL uses discrete sinusoidal lines and may be
synchronized to the FFT, ie the sinusoidal audio signals produced by the generator are of the same
frequency spacing as the FFT (called FFT noise in the text below). Consequently the measurement signal
at the display edges of the FFT can be continued without any transitions that no window function is
required for suppressing the FFT continuation error and an optimum frequency and level accuracy of the
FFT is obtained.
Measurement time and frequency resolution depend on the selected FFT size or on the frequency
stepwidth of the noise generator.
The smallest step of the 25-kHz generator is 5.86 Hz. This is therefore the maximum permissible
resolution for the FFT analyzer although a much better resolution could be obtained in the analyzer (with
the aid of ZOOM FFT). It is advisable to use 8 k FFT where the measurement speed still allows several
measurements per second to be made. The measurement speed can be further increased by reducing
either the frequency resolution or the FFT size.
At the generator side, generation and phase optimization of the noise signal involves much more
computation work than the generation of a simple sinewave signal. If all available sinusoidal lines are
used, the noise signal is available after about 1 minute. However, this time is only required once and any
number of highly accurate measurements can be carried out thereafter. By reducing the FFT size
(analyzer) or the frequency range (generator) the number of discrete sine tones can be reduced and the
signal generation time drastically shortened.
Note: The highest resolution (2.9296875 Hz at 8 k zoom FFT) makes only sense in the UPL, as the
UPD is not able to track a resolution of < 5.859375 Hz because of its higher internal generator
clock rate.
The frequency sweep and the FFT noise mode each have their pros and cons so that both modes are
employed (as far as possible) for the measurements described in the Application Note.