GENERAL PURPOSE Audio analyzers

44187

FIG 1 The Audio Analyzer R&S ® UPV shows what is possible today in audio measurements.

Audio Analyzer R&S ® UPV The benchmark in audio analysis

High-resolution digital media such Up to the limits tortion. It can perform fast and accurate measurements and as audio DVD place extremely high The Audio Analyzer R&S ® UPV (FIG 1) is simultaneously display the signals in a new compact instrument for any type the frequency and time domains. More- requirements on T&M equipment. The of audio measurement. If you work in over, it can replay audio signals via a a studio or develop and produce hi-fi and perform a wide range new Audio Analyzer R&S ® UPV meets and audio equipment, the R&S ® UPV of other tasks. A digital filter bank with can handle any measurement task up to weighting filters and user-definable fil- these requirements across the board – the limits of what is technically feasible. ters can handle virtually any require- High-resolution digital media such as ment. and also sets new standards in audio DVD can thus be mastered as perfectly as analog measurements up to 250 kHz. The generator in the R&S ® UPV pro- analysis. The analyzer’s outstanding technology duces all signals up to 80 kHz required in is easy to operate and ready for future the audio field, ranging from sinewave applications. For example, future audio and signals up to interfaces can easily be added via plug- signals and multisine signals with sev- in cards. eral thousand single lines. If you need more, you can use the built-in arbi- The analyzer in the R&S ® UPV mea- trary waveform generator or replay sig- sures level, frequency, phase and dis- nals in WAV format from the hard disk.

16 News from Rohde & Schwarz Number 183 (2004/III) All these signals can be output by using Numerous highlights Analyzer operation and measurement an additional digital equalizer with user- methods are always the same no matter definable nominal frequency response or ◆ Measurement bandwidth up to whether measurements are performed filtered in the time domain. 250 kHz on analog or digital interfaces. This is ◆ Dual-channel signal processing for truly a benefit for a variety of applica- With the Digital Audio I/O R&S ® UPV-B2 maximum measurement speed tions. For example, you can directly com- option, this variety of signals is also ◆ Simultaneous performance of pare measurement results obtained in available at the digital audio interfaces several measurements front of or after a converter. All mea- (AES/EBU, S/P-DIF and optical). In addi- ◆ Graphical representation of all surement functions and test signals are tion, physical parameters such as level, measurement results (FIG 2) available on both the analog and digi- jitter or sample frequency can be ana- ◆ FFT analysis up to 256 k points tal interfaces, enabling you to perform lyzed. ◆ Generator for all audio signals up measurements at any point on a mixed to 80 kHz analog/digital transmission path. This ◆ Dual-channel analog generator ensures efficient and comprehensive Landmark analysis concept ◆ Sinewave up to 200 kHz troubleshooting. ◆ Filters for analyzer and generator The entire analog measurement path ◆ Digital audio interfaces with sam- Since digital measurement routines can from the input to the A/D converter and pling rates from 30 kHz to 200 kHz continuously adapt their measurement the DSP is truly dual-channel. In stereo ◆ Plug-in cards for additional audio speed to the current input frequency, far measurements, this eliminates time-con- interfaces, e. g. for I2S higher measurement speeds than those suming switchover and settling opera- known for analog measurements are tions. The R&S ® UPV performs all mea- achieved. surements using digital signal process- ing. Signals to be measured are first sub- jected to complex preprocessing (fine- allows a higher dynamic range than that Wide range of measurement resolution levelling and fundamental offered by the internal 24-bit converter. functions rejection for measurements) It also ensures a level of performance ◆ Level, both selective and wideband using analog measurement modules and versatility that is far superior to that with rms, peak or quasi-peak weight- before they are digitized and fed to dig- offered by pure analog or digital measur- ing. ital measurement routines. This concept ing instruments. ◆ S/N ratio ◆ (harmonic distortion, THD+N, SINAD). The individual har- FIG 2 The R&S ® UPV displays measurement results in easy-to-read numeric values and graphs. monics can be displayed as a bar- graph, or the complete frequency spectrum of distortions can be dis- played. ◆ Intermodulation (modulation distor- tion, difference frequency distortion, dynamic intermodulation). The indi- vidual noise components can be dis- played as a bargraph. ◆ A digital prefilter can be looped into the signal path irrespective of the measurement function. One example is an A-weighting filter for acoustic weighting. Up to three further filters can be looped into the measurement path depending on the measurement function.

17 News from Rohde & Schwarz Number 183 (2004/III) GENERAL PURPOSE Audio analyzers

◆ Frequency, phase and group delay. measurements on the analog interfaces. ◆ Stereo sine. Frequency, level and ◆ Complex FFT (magnitude and phase) You merely have to select the type of phase are user-selectable in any up to 256 k points. filter (e. g. highpass/lowpass filter, band- channel. With the R&S ® UPV-B3 ◆ Post FFT for level, distortion and stop filter, etc) as well as frequency and option, this function is also available intermodulation measurements. attenuation in order to loop a new filter on the analog outputs. ◆ Waveform function for displaying into the measurement channel of the ◆ Two-tone signals. These signals are the measurement signals in the time analyzer or into the path of the gener- useful for intermodulation measure- domain. ator signal. In addition to these user- ments (amplitude ratios and frequen- definable standard filter functions, the cies can continuously be adjusted). Several measurement functions can be R&S ® UPV of course offers all common ◆ Test signal. You can use this signal performed simultaneously. For example, weighting filters (e.g. A-weighting, to measure dynamic intermodulation you can measure the output level, fre- CCITT-weighting or CCIR-2k-weighting) distortion (DIM). quency and phase as well as distortions for standard-conforming measurements. ◆ Multitone signals of up to 7400 fre- on a DUT and, at the same time, graph- quencies with selectable amplitude ically display the output signal in the distribution can be generated. You time domain (waveform analysis) and in Test signals for any application can couple the frequency spacing the frequency domain (FFT analysis). to the analyzer resolution of the fast ◆ Sinewave signals. You can insert an Fourier transform and thus quickly equalizer with user-selectable nom- and accurately determine the fre- Every filter is digital inal frequency response after these quency response of the DUT in a signals in order to compensate the single shot. The digital implementation of filters used frequency response of the test setup, ◆ Arbitrary signal. The R&S ® UPV can in the R&S ® UPV makes a virtually infi- for example. generate any voltage characteristic of nite number of filters available, even for up to 16384 points.

Superb operating concept

The R&S ® UPV is based on the Windows XP® Embed- ded operating system and thus offers a modern and intuitive user interface. When developing the instru- ment, Rohde & Schwarz kept its long-standing cus- tomers in mind. We retained many important fea- �������� tures of the R&S ® UPL operating structure as well as ������������� the names of parameter fields and functions. Users familiar with the R&S ® UPL will therefore quickly ����� master the new instrument. ���������������� ◆ All settings are made in panels that contain all relevant functions and settings. They can be arranged and scaled as desired (and minimized or closed) on the colour SVGA LCD. ◆ To get a better overview, you can distribute the ������� ��� panels on up to five virtual screens and quickly switch from one screen to another by simply

FIG 3 Convenient: You can select up to five virtual screens in no time by pressing a key.

18 News from Rohde & Schwarz Number 183 (2004/III) ◆ Sine burst and sine2 burst. The Excellent specifications Measurements at digital audio R&S ® UPV enables you to set the interfaces interval and on-time and to select the ◆ Level uncertainty 0.05 dB low level. ◆ Frequency response 0.01 dB The R&S ® UPV-B2 option provides the ◆ Noise. You can generate noise with ◆ Input noise typ. 1 µV instrument with balanced, unbalanced different amplitude distribution func- ◆ SINAD typ. 115 dB (analog), and optical inputs and outputs for con- tions. 145 dB (digital) necting professional studio and con- ◆ AM and FM. You can set AM and FM ◆ Analog sinewave signals with har- sumer equipment. Additional inputs and for sinewave signals. monic suppression of typ. 120 dB outputs on the rear panel allow you to ◆ DC voltage. You can set the DC volt- ◆ Noise floor for FFT typ. –140 dB synchronize operation to audio reference age, including an offset for the other (analog), –170 dB (digital) signals, to word clocks or to bit clocks signals. ◆ Maximum frequency resolution of and to generate such synchronization ◆ Dither. You can generate dither at fast Fourier transform of 0.2 Hz signals. The generator and analyzer can the level and amplitude distribution be operated independently of each other you need. Dither can be applied to with variable clock rates from 30 kHz to the digital audio signals. 200 kHz.

In addition to the audio content, the Linear or logarithmic sweep function of the analyzer, which makes R&S ® UPV can also analyze physical sweeps as fast as possible. Also, a time interface parameters. This enables you The frequency and level of signals grid (fixed or variable, read from a file) to display the jitter spectrum, to mea- can be swept with linear or logarith- can be set or the swept parameter can sure the jitter amplitude and frequency, mic sweep stepping. The generator can be manually stepped by using the rotary to generate output signals with jitter be synchronized to the measurement knob. and to unjitter input signals.

Moreover, the new analyzer can mea- sure the phase between the audio input and reference input and generate a phase shift between the audio output and reference output. The common- pressing a key (FIG 3). Thus, for example, you can mode signal at the balanced input can place infrequently needed configuration panels all be analyzed (frequency, amplitude, spec- on one screen and use another screen to display a trum), and a common-mode signal can fast Fourier transform in full-screen mode. be superimposed on the output signal. ◆ The instrument can be operated entirely from the front panel. The rotary knob (FIG 4) plays an impor- The R&S ® UPV measures the input pulse tant role. You can navigate within the panels by amplitude and the sampling frequency. using only one hand and select the desired func- ����� Since you can select the output level, tion by pressing the rotary knob. You can vary you can analyze the sensitivity of digi- numeric values directly by using the rotary knob. tal audio inputs. A cable simulator can This is of enormous advantage when making be added to the generator to simulate adjustments. long cables. ◆ Softkeys at the bottom of the screen give you fast access to changing functions. The contents of a selection field are displayed in this area, enabling Integrated PC you to also select the parameter without having to open the field. FIG 4 The rotary knob, which can also Neither a keyboard nor an external mon- be pressed, enables you to conveniently navigate within the panels. itor is required for analyzer operation but can be connected. In addition to a hard disk, the R&S ® UPV features a DVD drive and a CD burner. Large volumes of data

19 News from Rohde & Schwarz Number 183 (2004/III) GENERAL PURPOSE Audio analyzers

FIG 5 analysis are fast. Since these mea- Comprehensive surements are very frequent, total information: Min time is significantly reduced. and Max values, tolerance limits, ◆ Due to digital signal processing, the etc. internal setting and settling times are shorter than those obtained with purely analog instruments. ◆ An integrated program generator which, in the logging mode, gener- ates a complete and syntactically cor- rect IEC/IEEE-bus program line from each manual operating step mini- mizes the time required for creating control programs. ◆ Calibration intervals are lengthy due to the large number of digital compo- nents, yielding high instrument avail- can be transferred conveniently and graphical windows and thus simultane- ability. quickly by using a USB stick. Software ously visualize a sweep, the fast Fourier updates are child’s play owing to the transform and the waveform, for exam- familiar Windows®concept: you simply ple. If you change the size of the display Ready for the future start the required installation file from field, the analyzer automatically adapts the USB stick, CD or a network drive. legends, font sizes, gridlines, etc. As digitization progresses, it will bring about changes in audio technology The R&S ® UPV can be remote-controlled You can measure the graphical display and produce new measurement meth- via IEC/IEEE bus, RS-232-C and LAN, as of a trace with vertical and horizontal ods and interfaces. The Audio Analyzer well as from a detached PC via LAN by cursors. You can also superimpose limit R&S ® UPV is ready to meet these chal- using Windows®Remote Desktop. All lines and stored measurement results on lenges. Since all of its measurement common interfaces are provided: a trace and perform comparisons. You functions are implemented digitally, ◆ Four USB connectors for mouse, can display, store or evaluate groups of they can easily be adapted to chang- external keyboard, USB stick, etc traces for both measurement channels. ing requirements by simply updating the ◆ Connector for external monitor software. Two plug-in cards at the rear ◆ Parallel interface for connecting a of the instrument can accommodate printer Valuable tool in production additional hardware, e. g. new digital ◆ LAN interface for connecting a net- audio interfaces. work and for remote control Many of its features make the R&S ® UPV Walter Nestler ◆ IEC/IEEE bus and RS-232-C interface particularly useful in production: ◆ All measurement functions run simul- taneously on both channels. Com- Effective visualization of pared to other instruments on the measurement results market, this alone cuts the measure- ment time required for stereo mea- The numeric display panel shows up to surements in half. eight results in realtime for one or both ◆ In distortion and intermodulation channels and for several measurement measurements, the R&S ® UPV pro- functions. If a measurement function is vides digital methods that combine switched off, its display field will also be high accuracy with high measure- deactivated. Any representation can be ment speed. visualized with bars and limit value vio- ◆ Frequency response measurements More information and data sheet at lations, and you can also add Min/Max which are performed using the spe- www.upv.rohde-schwarz.com values (FIG 5). You can open several cial multitone signal and coupled FFT

20 News from Rohde & Schwarz Number 183 (2004/III)