Listening to chips

17 March 2009

The multichannel APx Digital Serial I/O.
The multichannel APx Digital Serial I/O.

High-speed tester for quality monitoring.

A new range of audio analysers was unveiled by Audio Precision at NAB 2009 in addition to some product updates. The new updates are a Digital Serial I/O, which provides multichannel, chip-level connectivity for designers of HDMI receiver/ transmitter chips, A/D and D/A converters, codecs, and other audio ICs and version 2.0 of its High Speed Tester (HST) application for the 2700 Series and ATS-2 audio analysers.

The High Speed Tester is used by national broadcast organisations to test the quality of their broadcast networks. An analyser is placed anywhere in the broadcast area and HST “listens” for a specific one-second multitone to be transmitted. When HST is triggered, the measurement results are automatically logged in a spreadsheet ready for email back to the station.

In 1.5 seconds, HST measures DC offset, output level, frequency response, interchannel phase, distortion, noise in the presence of signal, and crosstalk, and compares the results against user defined pass/fail limits. HST provides single value results for each measurement in a simplified user interface, but also allows the user to view the FFT spectrum of the acquisition for troubleshooting.

AP has been demonstrating with "Radio Free AP", an iPod with mini transmitter broadcasting the half second HST signal to a consumer radio receiver that's connected to an ATS-2 audio analyser with HST.

The multichannel APx Digital Serial I/O option allows engineers to test audio devices at the level of individual ICs rather than evaluating only the external inputs and outputs of a device. The digital serial option will be of particular interest to HDMI chip developers. When used with AP’s existing HDMI interface option, an APx analyser becomes an HDMI chip-debugging tool. The Digital Serial option allows all normal audio measurements to be carried out on A/D and D/A converters, codecs, DSPs, and sample rate converters.

There’s built-in support for most serial interface formats, including left justified, right justified, DSP and I2S, and the interface can generate and measure up to eight audio channels simultaneously using TDM or multiple data lines. Other innovations include independent input and output clocks, buffered oscilloscope monitors, and presets for testing audio devices.

AP also demonstrated the testing of a four channel automotive head-unit receiving an RDS-encoded audio stream over an FM transmitter using the new four channel APx526 and the APx LabVIEW driver in a simulation of an automated head-unit production test station.

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