DRM (Digital Radio Mondiale) is the universal, openly standardised digital broadcasting system for all broadcasting frequencies, including the AM bands, as well as VHF Bands. The great flexibility of DRM supports all types of coverage needs – from local, regional, nation-wide to international. If you want to listen to DRM broadcasts, you need a dedicated receiver or a software radio. This post will focus on the cheaper method, the software defined radio (SDR).
SDR performs demodulation in software. The RF signal is sampled by a high speed ADC (analog-digital converter) and sent to a computer which does the filtering, amplification, demodulation and decoding of the signal. The cheapest hardware for SDR is the popular RTL2832U based DVB-T stick.
Most DRM broadcast can be found in SW bands. Here comes an important issue. The tuner from the DVB-T stick can't receive this band. One of the solution is to add a frequency downconverter. Or you can simply disable the tuner and feed RF straight to the ADC. I wrote about RTL2832U direct sampling in this post. This method has some limitations, but nevertheless it should provide satisfactory results.
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| Dream decoding a DRM broadcast |
