Since the first time I heard about DRM for about 2 years, I decided to follow the developpment. DRM ist a digital transmission system for radio broadcast on shortwave. The transmitted information is not only sound (MPEG4-AAC coded) but also datas and pictures can be sent.

First Attemp

Burkhard Kainka developped a 2 transistors receiver. I could not wait on my receiver, so I decided to build this easy hardware on a Week-end. Everyone should be able to build his own piece. The receiving frequency is 3995khz. To be able to demodulate both sidebands, the receiver must be tuned a few khz above the receive frequency (~4002khz). Do not forget to invert the receive spectrum in the decoder software.
The first receive attemp was done with a W3DZZ shotwave antenna, I had many probles to receive something looking like DRM. I only heard some transmodulated Broadcast service. The second attemp was a litte bit better. As antenna I used about 30cm wire. In this case it was possible to hear DRM with 7dB Signal-Noise Ratio. It was not possible to hear some sound, only datas were decoded as shown on the pictures.


The receiver and the schematic


DReaM is working

Computer