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Digital Radio Mondiale (DRM) without modifications

The usual DRM solutions require a modification of the receiver. But this will cost some money and if you only want to get a short impression of DRM there is a better solution.

What you need is:



The AR5000 must be set to:
  • AGC SLOW
  • USB
  • 30 K bandwidth
  • 10 KHz (Shortwave) or 9 kHZ (Medium Wave) below the center frequency of the DRM transmission (6085 for RTL)

    Connections:
  • Connect the AR5000-Phones-Plug with Line-In of soundcard#1
  • Connect the output of soundcard#1 with Line-In of soundcard#2
  • Connect the output of soundcard#2 with the speakers (phones, home stereo or whatever you like)

    Start SR5 and configure the settings:
  • Tools > DSP and other settings > Highest frequency must be 22.050
  • Tools > Setup Audio Devices > choose soundcard#1 for in- and output and "line" for source
  • Start processing (F12 or )
  • Use Filter (F2 or )
  • Toggle filter window (right click on )
  • Shape out the DRM signal in the filter window while pressing the left mouse-button
    Now the signal is digitally pre-filtered.


    You can start the DReaM software now.
  • It must be configured for soundcard#2. (Settings > Sound Card Selection)
  • Adjust volumes with both sound card mixers to improve the signal quality.

    I could decode strong DRM signals like Deutsche Welle, Radio Kuwait, RTL, VoRussia and BBC over most of the time with this solution, using an average PC (2 GHz). Once a minute the signal usually interrupts, but it comes back again.

    Watch the SNR (View > Evaluation Dialog): Values of about 10dB are required for a station ID, 15dB is necessarry for audio reception. I rarely got an SNR of more than 20 dB.

    Some experience: No problems were caused by
  • Surprisingly, there were no big problems with heavy noise caused by an electric fence close to my antenna.
  • Two DRM signals close to each other (5800-5810 and 5810-5820 KHZ) don't cause problems

    Big problems with unwanted carriers:
    Any interfering carrier will lower the signal quality rapidly.
  • notch that carrier out with the SR5 software:
  • Some carriers apprear from the other side band. Vary the frequency!

    15 K bandwidth
    This filter works when you use only a spectrum like 0-10 KHz and boost the higher frequencies:

    Questions? Corrections? Ideas? Comments?
    Mail me: PeerAxel@aol.com

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