Test and Measurement News

Prism Sound Tests 'Smart' in-car RDS FM receivers for Blaupunkt

Cambridge, UK -October 2006: Blaupunkt is now using the Prism Sound dScope Series III audio analyzer for production quality control of Radio Data System (RDS) car radios.

The dScope Series III generator's bandwidth is over 90 kHz, which not only allows the system to generate FM stereo multiplex (MPX) signals, but also RDS data. Thanks to the ability to describe generator waveforms as Visual Basic Scripts, dScope III can generate the complete multiplex signal.

The audio stimulus used at Blaupunkt is a stereo multi-tone test signal that enables ultra-fast simultaneous measurements of audio amplitude, total distortion, frequency response and stereo crosstalk using the dScope Series III audio analyzer. The stereo multi-tone signal is encoded to the FM MPX along with the RDS subcarrier and data with a user-programmable text message to test the RDS decoder. The entire multiplex waveform is loaded to the generator of the dScope Series III system in the form of a wavetable and transmitted continuously in a looped mode.

Using this script, the test engineer can drive an FM transmitter directly from dScope Series III with the complete stereo MPX with RDS. The transmitter can then be connected directly to the receiver under test.

The script can be modified by the user, for instance, to change measurement frequencies or the RDS content shown on the receiver's display.

The necessary script and set-Up for dScope III Audio Analyzer are available for free download here.

FM radios that are equipped with RDS decoders are often called "Smart Radios" because they allow the user to select programmes and to only consider stations with a specific style without constantly using the station search button. Commuters or travellers can automatically receive traffic information even when listening to another programme. In peripheral locations with poorer reception of the preferred station, RDS will always ensure reception of the selected programme's stronger station.

An RDS receiver can also receive and show radio station text messages and compare the vehicle clock with the radio transmitter's exact time.

The Prism Sound dScope III audio analyzer has been the preferred measurement instrument of numerous audio equipment manufacturers for many years. In addition to multi-tone measurements, dScope Series III provides comprehensive coverage of more traditional test methods such as swept sine frequency response, THD+N etc. Using dScope Series III, it is also possible to perform CD drive tests, if one is included. This FM-MPX/RDS Test Script offers added value to car radio manufacturers and can be further customized either by the user or by Prism Sound's applications team.

You can download the FM MPX Script (Zip 1.5MB) - including documentation - here from the Prism Sound homepage. The documentation can be downloaded separately via this link (PDF 753KB).