DSD+ Single Frequency Decoding

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rkillins

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Is it possible to decode single MOTOTRBO non encrypted frequencies using DSD+. There are several local businesses using MOTOTRBO and I'm hoping to be able to monitor them.

I have managed to get DSD+ working on a local DMR trunked system, but unsure how to go about doing it for a single VHF non trunked frequency.
 

Markb

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Enter the frequency of what you want to listen to and it should decode. Nothing special required.

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rkillins

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That simple? No configuring of FMP or VC batch files?
The frequency is being tuned via a discriminator tapped radio and the voice going out by rtl-sdr.
 

Markb

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I run the trunked batch file and the VC side sits idle while the CC side works to decode non-trunked voice and data. Should work regardless of what mode you are monitoring.

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Markb

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Wait......hold the phone.

Not sure about that one. Haven't tried it that way. I don't believe that will work, but someone else might be able to steer you in the right direction.

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rkillins

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I'm missing something ....
I have my radio tuned to the MotoTrbo frequency, which is inactive currently. Periodically I get a burst of noise.

I run DSDPlus.exe. It's comes alive but busy trying to decode the DMR system I was playing with earlier.
Strangely, the DSD+ source audio scope is showing a signal, yet the radio source is quiet.
 

Forts

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Are you feeding it with a tapped radio? If so the signal meter will always show some sort of signal (background noise basically) but will lock onto the DMR signal when it's present. You should see a significant change in the signal meter when this happens.

And as already mentioned, a conventional frequency doesn't require anything special. If you have it working for trunked systems you shouldn't have any issue with conventional.
 

Markb

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Yeah, retract my last post. I dont know what I was thinking. [emoji15] [emoji15] [emoji15]

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slicerwizard

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That simple? No configuring of FMP or VC batch files?
The frequency is being tuned via a discriminator tapped radio and the voice going out by rtl-sdr.
No. For a conventional (non-trunked) single-frequency DMR signal, you feed DSD+ with *either* a tapped radio or an rtl-sdr dongle, not both.

Sounds like you want to feed DSD+ from your tapped scanner, which you will tune to some digital transmissions. The tap's audio is being fed into a line or mic input on your PC? DSD+ has to have its input directed to that audio source. To do that, you need to have the <number> part of the -i<number> parameter on the DSD+ command line pointing to that audio source.

I'd suggest copying your VC.bat file to a new file - Discriminator.bat; just use Notepad to create the new file as well as to copy the text from VC.bat

Then just edit the new batch file; you don't need -rc so get rid of that, and change the -i number to the right number for your mic/line in input. You can get better performance out of DSD+ if you limit its decoding to the type of signal you're monitoring, i.e. add -fr to the command line for DMR-only decoding, but then DSD+ won't recognize any other digital signals, like NXDN, P25 - so your call on that.

Any time you want to feed DSD+ from your scanner, just run your Discriminator.bat file. No other programs are involved - no FMP, Unitrunker, etc. required.
 
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