Trouble with Unitrunker and DSD+ voice

[bama9999]

I'm having a bit of trouble trying to hear a Provoice system while using Unitrunker and DSD+. I'm using a BC355N with a discriminator tap for my signal source, and everything is ok with that, and it's trunking the system like it should. I'm using one of the RTL dongles for the voice receiver and that seems to be where the problem is. I tried the dongle as the signal receiver, and it receives the control channel fine, with a health of 98 to 100 most all of the time. It's just when it's used in the voice receiver roll that it doesn't seem to work right.

The audio is not decoding good at all in DSD+, and also there's a lot of what sounds like static between voice calls, and I've tried maxing out the squelch and it doesn't help.

Also, if I just scan the voice channels of this system conventionally, and pipe it into DSD+ from the discriminator tapped BC355N, it sounds great, but when going through Unitrunker with the dongle, I get the bad decoding and the static noise, which is present with the garbled decode.

I hope I was clear enough, but I'll be glad to add more info if needed, if anyone has any ideas or suggestions. Attached in a pic of the waveform of the static/interference/whatever, and also two shots of my audio receiver in Unitrunker.

Any help appreciated.

 

[bama9999]

Also to add, I've tried adjusting the gain settings from 0 to 500 in increments of 10, and that doesn't help, and when I use auto gain it doesn't seem to make much, if any, difference.

One kind of odd thing that I did notice, is that when checking and unchecking either the baseband AGC or the auto gain boxes, it seems to be a good bit clearer, but just for a fraction of a second and then it's still bad.

I'm using the latest version of Unitrunker and DSD+, but have tried earlier versions of both with no difference noted.

Thanks again.

 

[rosecitytransit]

One idea is try using SDRSharp (or similar) with the dongle and see if DSD+ will decode audio piped from it.

 

[bama9999]

Thanks for the post. It being a Provoice system, it's hard to be quick enough to click on a voice call before it changes frequencies, using SDR#, but on the ones I was able to click and listen to, they didn't decode fully either. I notice also that the voice frequencies are not quite as strong as the control channel frequencies while viewing them on SDR#, so maybe that's the problem.

 

[rosecitytransit]

There's plugins out there for SDRSharp that will scan through a list of frequencies so you don't have to play whack-a-mole.

 

[bama9999]

On SDR#, the signals I am trying to decode are showing to be received at the -15 level. Should that be strong enough for DSD+ to decode them successfully? The FD's that transmit in analog sound fine, but no joy on the digital stuff.

 

[SCPD]

What command tail do you use to run DSD+?

Try "-mp -fp" plus whatever input and output options you normally use.

 

[bama9999]

Rick,

I've just been running DSD+ with the defaults, except for setting my input to the virtual cable.

I tried your suggestion above, and oddly enough, it wouldn't decode anything, but loading the default settings and trying it, it was at least attempting to decode voice traffic.

 

[DSDPlus]

-mp is for P25 CQPSK.

Can you upload raw recordings from voice channels? From FMP and UT would be best.

 

[bama9999]

Ok, I hate to ask this and look like a total idiot, but what exactly do you mean by raw recordings? How would I go about that?

 

[SCPD]

what exactly do you mean by raw recordings? How would I go about that?

From the dsdplus.txt readme file ...

Active keys:
R Start/stop recording of raw source audio to wav file

-mp is for P25 CQPSK.

Thanks. I was thinking of a switch to enabling GMSK in that *other* program.

 

[bama9999]

Thanks Rick. Although that was staring me right in the face, obviously I somehow missed it.

Much appreciated, and I sent the file to DSDPlus by email, so hopefully he'll be able to see what's happening.

 

[bama9999]

Problem resolved. Decided to uninstall, then reinstall VB Audio cable, and now it is trunking and decoding the voice channels just fine.

Thanks to all who offered assistance.

 

[dooshorama]

interesting.
i had a working setup with P25 and then suddenly ended up with a lot of voice breakups in DSD+. i falsely attributed the problem to the new version of SDR#; however the problem gradually got worse regardless of the tuner-software and was finally fixed by reinstalling the VB audio cable driver.

 

[DSDPlus]

Listen to the file you submitted. Use Windows Media Player. You will hear raw ProVoice data AND synthesized audio. You had the DSD+ output looped back to the DSD+ input. This degrades decoding very much.

This may be a common problem for new users. Maybe DSD+ should do a loopback test at startup?

 

[bama9999]

No idea how I did that, as I thought I was following the directions I read. But thanks for the replies, and I'm glad it's working as well as it is now. It's still not 100% perfect, but at least I can listen to it now, as I try to further improve it.