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Mission Europe

DW Presenter Builds DRM Receiver

DRM receivers with which you can listen to Update Europe are still expensive and the choice is limited. DW's Mark Caldwell solved the problem by picking up a soldering iron and converting to Linux.

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DW Radio Presenter Mark Caldwell

The receiver Mark built is described in the March 2004 edition of the German language electronics magazine Elektor. It can tune into stations between 500 KHz and 20 MHz, taking in most of the medium- and short-wave bands.

The Elektor receiver (March 2004) as built by Mark Caldwell Picture mark caldwell

The Elektor DRM receiver (March 2004) as built by Mark Caldwell. Bottom left: Power input 9v DC. Above left: cable to serial port. Top right: antenna. Middle right: line-in

It picks up a DRM short-wave signal, for example, Deutsche Welle on 5975 kHz, and mixes it down to an IF (intermediate frequency) of 12kHz. This is then fed to the line-in of a PC equipped with DRM Dream decoding software. Mark downloaded the software (Dream 1.0.6) from Darmstadt’s Technical University, and then compiled and installed it using Linux SUSE 9.1 Professional Edition.

The DRM signal carries information about the station you are tuned to (see below). The name of the station will appear before you can hear it. The signal is either there, or it isn't. There is none of the fading, distortion or interference that plagues analogue transmissions. However, if the signal falls in strength below a certain level, it cuts out altogether.

The main panel: Dream is decoding a signal from Deutsche Welle's transmitter at Wertachtal Picture mark caldwell

The main panel: Dream is decoding a signal from Deutsche Welle's transmitter at Wertachtal Picture mark caldwell

The three green markers light up when the decoder is fully operational

Input signal seen by Dream. Note the typical elongated top hat DRM waveform Picture mark caldwell

Input signal seen by Dream. Note the typical elongated top hat DRM waveform Picture mark caldwell

A DRM signal displayed by the Dream software

How does the receiver perform? The sound file of Deutsche Welle’s German Service on this page was recorded with just a meter of wire as an antenna. "It copes well with strong signals in the evening, but I'm going to improve reception by connecting a better antenna" Mark says. "I’m delighted with the whole installation and if - like me - you’re interested in the technology, then it's difficult to imagine a better introduction to DRM."

Please see the links below for more information

WWW links

Downloads