Audio Precision uncrates PDM interface for MEMS microphone test

May 2, 2012 – PRNewswire — Audio test tool supplier Audio Precision (AP) released a pulse density modulation (PDM) audio interface option on its APx500 for direct I/O, modulation, and decimation for designers of micro electro mechanical system (MEMS) microphones and other PDM devices.

Learn more about the APx PDM interface here.

PDM is a one-bit, high rate data stream that conveys a signal by modulating the density of the pulses. AP’s PDM option supports 4th and 5th order modulation; interpolation ratios of 32, 64, 128, and 256; and the ability to analyze an undecimated PDM bitstream.

A 50x interpolation ratio will be available in Summer 2012.

The PDM option includes a built-in power supply for devices under test (DUT), and can directly measure power supply rejection (PSR) in PDM devices. Users must have APx500 v3.0 software, which may be downloaded free of charge.

AP’s audio test instrument APx500 also includes a new PESQ software option for fully automated testing of speech quality with any audio interface, generating MOS (Mean Opinion Score) results. The APx PESQ software option allows the results of many tests to averaged, and may be used with any audio interface, including analog, DSIO, Bluetooth and PDM. In addition to support for PDM and PESQ, APx500 v3.0 enhances the DSIO (Digital Serial In/Out) with support for up to 16 channels of TDM at 96 kHz, variable TDM word length and accommodations for TDM variations used in a wide range of DSP products.

Audio Precision makes audio test instruments and applications. For more information, visit

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