M9260A PXIe Audio Analyzer Module

M9260A PXIe Audio Analyzer Module

Data Sheets

M9260A PXIe Audio Analyzer Module

What is an Audio Analyzer? An audio analyzer is a test and measurement instrument that is used to quantify the audio quality of electronic and electro-acoustical devices, including but not limited to the following:

  • Radio
  • Mobile phone
  • Bluetooth® audio device
  • Broadcasting system
  • Home theater
  • Speaker
  • Microphone
  • ADC/DAC
  • Audio/Low-frequency amplifier
  • Automotive infotainment system
  • Hearing aid

Typically, audio quality metrics comprise the level gain, total harmonic distortion (THD), total harmonic distortion plus noise (THD+N), crosstalk, relative phase of signals and frequency response, among others. The three important characteristics in the selection of an audio analyzer. It’s cost and technically difficult to improve these characteristics.

  • Purity of signal generation: How certain are you that the signal received by the DUT is the

signal generated by the audio analyzer?

  • The residual total harmonic distortion and noise (THD+N): If your device under test has

excellent performance it will just generate very low noise and distortion. To test your device

you need an audio analyzer with very residual low THD+N.

  • Test speed: How fast can the audio analyzer test multiple device under tests (DUTs) in the

production line?

The M9260A PXIe Audio Analyzer is Not your Traditional Digitizer

The Keysight Technologies, Inc. M9260A PXIe audio analyzer module is designed for fast, high performance audio measurement, unlike traditional general-purpose digitizers. The M9260A build includes two audio generator channels and two audio analyzer channels in a single 3U height PXIe module.

Key features that make the M9260A uniquely fast and accurate include:

  • Large 1-million-sample arbitrary waveform buffer that speeds up signal generation
  • Large 1-million-sample input buffer that speeds up signal acquisition and analysis
  • Gain of 5 amplifiers that increase signal sensitivity, leading to accurate replication of signals

to and from the DUT

  • Super-linear, low-noise analog-to-digital converters (ADC) and digital-to-analog converters

(DAC)

  • Signal generation with ultra-low residual distortion of -106 dB and 1% amplitude accuracy

Additional built-in features of the M9260A PXIe audio analyzer that make it a worthy investment:

  • Built-in loopback system helps with self-calibration of the “generator” and “analyzer” blocks,

hence ensuring the quality and accuracy of signal used for test

  • Built-in multiple impedance selection allows convenient impedance matching to avoid errors

due to mismatched impedances in the test system

Pure Audio Signal Generation

A pure or clean audio signal is defined by a signal with very low distortion and noise. One of the common contributors to signal distortion in traditional digitizers is phase discontinuity. Traditional digitizers typically come with relatively small arbitrary waveform buffers that can only house a maximum of 1K to 2K samples. For complex test signals that exceed this capacity, usually several hundred thousand samples, the signal needs to be ‘chopped’ up into multiple pieces and then ‘stitched back’ together to recreate the entire waveform. The ‘stitching back’ is where phase discontinuity inevitably happens. With the M9260A PXIe audio analyzer module, you can transmit up to 1 million samples of signal all at once, owing to its large arbitrary waveform buffer, which avoids the issue of distortion due to phase discontinuity. Distortion in audio signal generation can also be caused by the non-linearity of output amplifiers. Typically, this can be resolved by using an amplifier with a higher gain. While a traditional digitizer module typically has only three ranges (gain of 3), the M9260A PXIe audio analyzer module has five, resulting in an output that’s relatively more linear and accurate. With the M9260A, you can achieve:

  • THD+N (20 Hz to 20 kHz): –103 dB (≥ 1 Vp)
  • THD (20 Hz to 20 kHz): –106 dB
  • Amplitude accuracy: ± 0.087 dB (± 1%)

High-Performance Audio Measurement

Leveraging the design of the high performance Keysight U8903B audio analyzer, the M9260A PXIe audio analyzer module provides reliable audio measurement capabilities that matches its pure signal generation.

  • Amplitude accuracy: ± 0.58% for AC, ± 1% for DC
  • Low input residual distortion and noise: –95 dB at1 kHz, 20 Hz to 20 kHz BW
  • Residual THD: –101 dB at 1 kHz, 20 Hz to 20 kHz BW
  • Max input amplitude: 46 Vp
  • Flatness: ± 0.08 dB (20 Hz to 88 kHz BW, ≤ 10 Vp)
  • Ultra-low crosstalk for multi-channel measurement: –123 dB (20 kHz BW)

High-Speed Production Testing

In high-throughput production testing, speed is critical. The M9260A PXIe audio analyzer module is designed to optimize testing speed in two ways: fast signal generation and fast signal analysis. Figure 1 illustrates the blocks within the M9260A that define its unique high[1]throughput capability.

Fast audio signal generation

There are two ways for a signal to be generated by the M9260A. The first method is to have the test signal created via the PC software and then loaded to the M9260A arbitrary waveform buffer. The M9260A PXI module then generates the test signal according to the arbitrary waveform description, to the Device Under Test (DUT).

Large 1-million-sample arbitrary waveform buffer

Traditional digitizers typically come with relatively small arbitrary waveform buffers that can only house a maximum of 1K to 2K samples. For complex test signals that exceed this capacity, usually several hundred thousand samples, the signal needs to be first ‘chopped’ up into multiple pieces, and then sequentially sent to the PXIe module. The total processing time can be significantly reduced with the M9260A PXIe audio analyzer module, as it comes with a large 1-million-sample arbitrary waveform buffer. This means you can transmit any waveform of up to 1 million samples, to the M9260A module once, without having to face buffer and speed limitations that are common with traditional digitizers.

Built-in waveforms

In addition to the large arbitrary waveform buffer, Figure 1 also shows that the M9260A PXIe audio analyzer module comes with built-in waveforms that speed up the signal generation process further. Commonly used waveforms that are built into the M9260A include the sinewave, dual-sinewave, variable-phase sinewave, DC, Gaussian noise, rectangular noise and pink noise. Having these waveforms built in means you do not need to generate the test signal with a PC software. All you need to do is send a software command to the PXIe module and indicate which of the built-in waveforms you would like to generate. The PXIe module then sends the signal almost immediately to the DUT, reducing significant signal generation time.

Fast audio signal analysis

For signal measurement, the M9260A receives the incoming test signal from the DUT, after which the signal goes through signal conditioning and the analog-to-digital converter before it is sent to the input buffer where the signal ‘waits’ to be streamed back to the PC for analysis. Large 1-million-sample input buffer As with its large arbitrary waveform buffer for signal generation, the M9260A PXIe audio analyzer has a large 1-million-sample input buffer, which means a virtually ‘limitless’ memory for acquisition and seamless streaming to PC. This is unlike traditional digitizers that typically provide a smaller 1K input buffer size that limits the signal measurement capability to just 1 thousand samples at any one time. With the M9260A module, you can achieve fast audio signal acquisition and analysis for high-speed production testing.