DRM without modifications on the AR5000 (and other scanners)

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:

a PC with 2 soundcards
a scanner with SSB and IF filters wider than 10 K
DSP software like SR5 (free)
DRM decoding software like DReaM (free, compiled)
If you cannot find the compiled version under that link ask Google

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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radiovibrations.com/aordrm.htm