DSD+ setup help needed

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kkomarica

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Hello everyone

I'm new to this forum and I am here because am interested in SDR and I'm trying to set up DSD.
I have problems with DSD. I have read and followed some of the tutorials online and double checked everything but still no luck in decoding ... hope that you guys can help me.

I use SDR#, Virtual cable and DSD+. In SDR# output is set to virtual cable line1, and output sample rate is set 48000.
Virtual cable line 1 is set as the default recording device.
DSD+ is installed according to instructions, and when started it shows that the input device is Line 1 Virtual Audio Cable.
The last line is in DSD+ is: "Mono audio decoding initiated;"
Here is where i get stuck, DSD doesn't show any data being received and/or decoded despite the SDR# being active and receiving what I believe to be some DMR/Mototrbo transmissions (if needed I can provide samples).

I hope that someone can look at this and help me in finding my mistakes ... thanks!

Kris
 

frazpo

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Are you running the audio "unfiltered" ?
You didn't mention that.
 

n4yek

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Try moving your frequency up or down by 100 Hz increments. I found that even though everything on my setup looked ok, i had to actually move off the frequency a little for decoding to start. Not sure why my setup is like this but it is the only way I can use SDR# and DSD Plus together.

Just something to try.
 

kkomarica

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I have tried both filtered and unfiltered audio, I have tried different bandwidths, a also tried fine tuning the frequency ... no luck.
A question ... would there be any visual activity in the dsd (dsd+) if the received signal was not DMR modulation, but something else (fm, am, tetra)? My guess is that it should show some activity ...
 

frazpo

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Find a p25 control channel to mess with. Its constant and usually are easy to pickup and decode. At least this will let you see if your getting good audio to DSD+
 

mm

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another thing,

Set your sdr dongle gains with dsd+ bypassed at first, enable your PC speaker audio in sdr sharps AUDIO section under OUTPUT, and listen to the digital data thru the speakers while adjusting the dongles gains as described below.

You want to adjust for a clear digital signal without any overloading present.

Also Set the dongles frequency correction, in sdr sharps configuration, by tuning to a known broadcast such as a weather channel and center the signal on sdr sharps spectrum display, then adjust the ppm correction.

To get fine spectrum display resolution for centering the exact frequency, set the sdr sharp FFT DISPLAY resolution to 65536 or higher and zoom in with the spectrum displays up/down ZOOM slider.

You will probably also need to experiment with the dongles RTL AGC AND TUNER AGC, in the CONFIGURATION menu, to find the optimum setting of your particular dongle by listening in speaker mode, bypassing dsd+, to a off air weak station.

Don't be afraid to disable both of these AGC settings either and set the AGC manually by using the RF Gain slider and you don't really need to set to maximum dongle gain either, you really want the clearest/strongest possible signal without any Intermod distortion and also set the SAMPLE RATE TO 2.048 MSPS or less and make sure QUADRATURE SAMPLING is set.

In sdr sharp, under RADIO menu try enabling CORRECT IQ, AND TURN OFF SQUELCH and for digital set the FILTER BANDWIDTH around 9000 to start.

do not turn on FILTER AUDIO and do not turn on UNITY GAIN, leave these off.

Next set your audio path back to use Dsd+ and watch for a valid known digital signal on the sdr sharp spectrum display and at the same time adjust the sdr sharp AUDIO sections AF GAIN slider so that dsd+ shows a LVL =, on the top of the dsd+ screen, between 30 and 70% which I found perfect for 2 different model of dongles tested.

Try these items and let's see what the outcome is?

I'm listening to a P25 station 75 miles away with a downstairs quarter wave antenna with a 98% decode rate on my E4000 dongle.

No matter what the digital signal is, and within the capability of dsd+ capability, you will see a scrolling indication of the digital signal if it's present.

Mike
 
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kkomarica

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Thank you all for your messages and your help!

Mike, since i'm using sdr# for a while now I have it already setup correctly, but I have tried your suggested settings and nothings changed.
The real problem is that I don't know if any kind of signal is getting to DSD! Regardless of settings, and fine tuning I don't get any feedback in the DSD window.

My conclusion is that it's something to do with audio/recording settings, and that the signal from the sdr# is not getting to dsd+.

Can someone in detail describe their audio settings.
 

mm

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ok,

it sounds like the audio in/out is not set correctly.

in SDR sharps Audio section set 'Input' to 'Windows direct' or something similar sounding as every pc is slightly different.

In SDR sharps 'Audio section' under 'Output' look for '[MME] CABLE INPUT (VB-AUDIO VIRTUALL)' or whatever selection is closest.

Also your pc audio needs to be set up also, in CONTROL PANEL SOUNDS LOOK FOR 'Playback and set 'Cable input' VB-AUDIO virtual cable as default.

For audio/Sound Recording set 'Cable Output' VB-AUDIO Virtual Cable as default.
 

foxtail

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I have sat on dmr channels that did not transmit till it was time too. So there are times that there may be no noice coming from the chl. your trying to hear. Keep that in mind...
 

EricCottrell

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Hello,

Also some DMR repeaters will transmit data idle messages every minute or so. This allows the radios to select the repeater with the strongest signal when multiple repeaters are linked together.

73 Eric
 

kkomarica

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Thanks to everyone ... dsd+ is working now.
I guess that the problem was in the receiving channel ... I don't get a lot of dmr traffic here, and when I did the dsd+ started working. Also I installed a sdr# plugin that controls dsd+ directly from sdr#
 

stanogs68

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i had this problem ,well its not really a problem you just need a strong signal and it will start decoding ,i was stuck like this for ages then i found a constant strong signal ,and bingo ! good luck
 

stanogs68

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im having the same problem under windows 10 ive set the dongle up set sdr ti vb cable input ,playback vb cable and set that on the widows settings as well ,the sdr works when speakers set as defaut but dsd wont decode ,set the winows settings to vb cable and sdr works mdsd decodes but know sound ,lost were to do next
 
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