another DSD post...so close but..

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KA2ZEY

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So I installed Windows 7 via Bootcamp on my new MacBook Pro (very current spec). SDRSharp and HDSDR work great but still can't get DSD to decode anything intelligible. Obviously I've gotten the virtual cables routed correctly because DSD is trying to decode something and I can hear audio. Everything is at 48K as the instructions recommend. I've messed with the AF output on SDRSharp as well as the system volume. The higher the volume the higher the percentage of decoding. I've also messed with the RF Gain of my RTL dongle to make sure the signals were nice and strong. I live on the 15th floor of an apartment in NYC so signal strength is not a problem. I've also experimented with changing -XR -MA and -FR in DSD. Does anyone have any other parameters that I might be missing? Perhaps something with the Filters?
 

KA2ZEY

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I should also add that I am using the free VBCable and not Virtual Cable. Not sure if that might be the problem.
 

mtindor

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DId you uncheck "Filter Audio"? If not, then you'll have tremendous difficulty. Leave "Filter Audio" unchecked and set bandwidth between 8000 and 10000.

Mike
 

Boatanchor

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So I installed Windows 7 via Bootcamp on my new MacBook Pro (very current spec). SDRSharp and HDSDR work great but still can't get DSD to decode anything intelligible. Obviously I've gotten the virtual cables routed correctly because DSD is trying to decode something and I can hear audio. Everything is at 48K as the instructions recommend. I've messed with the AF output on SDRSharp as well as the system volume. The higher the volume the higher the percentage of decoding. I've also messed with the RF Gain of my RTL dongle to make sure the signals were nice and strong. I live on the 15th floor of an apartment in NYC so signal strength is not a problem. I've also experimented with changing -XR -MA and -FR in DSD. Does anyone have any other parameters that I might be missing? Perhaps something with the Filters?
You don't mention what you are trying to decode, but if P25 Phase 1 then try this command line in your DSD batch file:

dsd160 -i/dev/dsp -o/dev/dsp -f1 -mc -u1

I run SDRSHARP. DSD1.60 and VB Cable on a cheap 1Ghz Windoze XP laptop and it decodes P25 just fine on the above settings. Obviously, there is something odd going on because you are forcing DSD to run in GFSK mode instead of C4FM, but it works for me.

I get very poor decode with C4FM and nearly perfect decode on GFSK.

I have a feeling that DSD's GFSK mode is a little more resilient to the 48K sample rate conflicts that are going on between SDRSharp and DSD. Then again, I have found that GFSK also works very well on direct/discriminator taps, so who knows..

BTW, set your main filter bandwidth to about 7000Hz-8000Hz for best results on P25 and make sure you center your received signal in the middle of the receivers bandpass window (the light grey area in the spectrum analyzer window). This will probably require you to calibrate your USB receiver dongle by using the frequency calibration setting in the receiver config window of SDRSHARP.

Good luck..
 
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