DSDforWin with Moto Mobile

[warpedspeed]

Hi all,
I am try out DSD for Win and not having much luck. I am using Windows 7 Pro, x64 SP1.

First question – Has anyone tried with a commercial radio, such as Moto Maxtrac or Spectra with the “Detected” audio line? I have tried a couple of Spectra’s with no success. I have a 16 pin Maxtrac laying around that I could try too.
I am using a DC blocking cap and a 600ohm isolation transformer between the radio and PC.

Is anyone successfully decoding Trbo (+DMR) with DSD Win? We have a Trbo repeater here in town, but I am not able to monitor. RF signal strength is excellent. I am hearing bits and pieces of audio, but nothing usable. I have the audio set so that Inlvl is running about 38 - 44%. I tried –xr but got “unknown burst type”.

Here is a capture of what I am seeing with Trbo.
Sync: +DMR mod: C4FM inlvl: 43% [SLOT0] SLOT1 VOICE e:=======R====R===
===R=====R======R====R======R=======R====R======R
Sync: +DMR mod: GFSK inlvl: 43% [SLOT0] SLOT1 VOICE e:=======R======R=
====R======R======R=====R======R======R
Sync: +DMR mod: GFSK inlvl: 44% [SLOT0] SLOT1 VOICE e:=====R==========
========R==========R=========R==========R=====
Sync: +DMR mod: C4FM inlvl: 44% [SLOT0] SLOT1 VOICE e:====R==========R
=========R=========R========R==========R====
Sync: +DMR mod: GFSK inlvl: 43% [SLOT0] SLOT1 VOICE e:====R======R====
=====R=======R=========R=====R======R=========R
Sync: +DMR mod: C4FM inlvl: 43% [SLOT0] SLOT1 VOICE e:====R=========R=
========R=================R=============
Sync: +DMR mod: GFSK inlvl: 42% [SLOT0] SLOT1 VOICE e:=========R=====R
======R====R======R=====R=========R==========R=====
Sync: +DMR mod: C4FM inlvl: 43% [SLOT0] SLOT1 VOICE e:====R======R====
=R======R====R======R=====R======R====R=========R=====

How about P25? I figured that one would be easy. I get no decode at all and nothing in the errorbars display.

Thanks for your help.

Dean

 

[kma371]

The audio is too high. I think it's supposed to be set between 6 & 7 %

 

[warpedspeed]

I tried that with no luck, in fact sometimes DSD cannot identify the Trbo data at that level.

I have tried walking up the audio level, one increment at a time, bottom to top, with both Trbo and P25 with no success (Inlvl at the bottom of the input range is 2%). In fact it never sees anything for P25 at all. The P25 part is what really

I talked to one of the users of the Trbo system today and he indicates that it is +DMR and not negative.


Dean

 

[warpedspeed]

Got interrupted on the P25 sentence, then lost track.
Anyway, the P25 part is what is really strange to me. I would figure that would have been one of the easier decodes.

 

[KC1UA]

From my experience, the display you show above indicates that you are receiving in the wrong polarity. I realize your source told you that the signal is +DMR but I don't believe that makes a difference to your system. I have seen computer A run +, and computer B run - on the same system when using DSD.

 

[kma371]

Try running reverse polarity

 

[n4yek]

Are you using a discriminator tap or are you trying to pull the audio from the speaker jack?
If you are trying it from the speaker jack, it is filtered audio and you won't be able to receive the complete stream of data.
Just a thought.

 

[warpedspeed]

And this gets back to my original question. It is "detected" audio. Many commercial radios do not have a discriminator in the classic sense. What Motorola calls detected audio is what is usually used when interfacing with equipment that needs raw unfiltered audio / data information that is not filtered or de-emphasized. Hopefully this makes sense.
I know that there are better explanations on the web regarding how Quadrature Detectors are used in Motorola radios.

Regarding the question of + or - DMR on Trbo, last night I had a chance to try the -xr switch while there was some activity on the Trbo repeater in question. Still no luck, from 0 to 100 on the audio input slider. Most of the time there were quite a few “unknown burst type" messages, although that was lessened when inlvl was was around 40%. In the 5% to 7% range of inlvl, it was mostly “unknown burst type". Also, still nothing at all with P25 signals, no matter what the setting for inlvl. That is what has me scratching my head...

Unless "Detected" audio is not usable. That is why I am here asking.

Thanks

Dean

 

[warpedspeed]

Well it appears that the Spectra version of "detected" audio may be a problem. I rigged up a cable for my Kenwood TH-F6A and it is working on the same PC. It is also seeing P25 now, although it is not able to quite lock in on the audio. The Trbo repeater in question was +DMR FWIW.

I think that the Kenwood also uses a Quadrature Detector, but maybe the frequency response is a little better on the output line, since it is designed to work with the Amateur flavor of FSK packet.

If I get a chance sometime in the future, I may try a Maxtrac just for grins, although I suspect that the result will be the same as the Spectra.

I wish I had a few extra hours laying around so that I could put a tap in my trusty old Pro-2006.
Maybe I need to get the Flu one day. ;- >

Dean

 

[mancow]

A spectra has no flat "detected" audio output. I know because I spent hours dissecting the service manual and radio for a flat audio "poor man's P25 repeater" at one time in the past. The receiver board process everything in a manner that the audio is filtered prior to exiting a chip on the receiver board so there is no access to that that portion of the audio chain.

The maxtrac you mentioned should do very well.

 

[warpedspeed]

And we are back...

That only took a couple of months. !

Sometimes it is good to be wrong.
I had a suspicion that a Maxtrac would suffer similar Detected Audio problems that the Spectra had. I finally had a chance to try it tonight and it worked well. A .1 uF cap to block the DC and 33K resistor in series and the sound card was happy. I tried a 10K R, but I could not get the inlvl below about 12% with that one.

P25 IMBE digital sounds relatively good too.


Dean