Interpreting DSD information/unintelligible audio

[alpharaysmax]

I've been attempting to monitor the police department one county over—not very far away—that is using a MOTOTRBO system. Things are almost working, except that I can't understand any of the audio that DSD produces.

Here's a sample of its output when someone speaks:

Sync: -DMR mod: GFSK inlvl: 7% slot0 [slot1] CSBK
Sync: -DMR mod: GFSK inlvl: 6% [slot0] slot1 RATE 3/4 DATA
Sync: -DMR mod: GFSK inlvl: 6% slot0 [slot1] DATA Header
Sync: -DMR mod: C4FM inlvl: 7% [slot0] slot1 RATE 3/4 DATA
Sync: -DMR mod: GFSK inlvl: 7% slot0 [slot1] DATA Header
Sync: -DMR mod: GFSK inlvl: 6% [slot0] slot1 RATE 3/4 DATA
Sync: -DMR mod: GFSK inlvl: 7% slot0 [slot1] RATE 1/2 DATA
Sync: -DMR mod: GFSK inlvl: 7% [slot0] slot1 RATE 3/4 DATA
Sync: -DMR mod: GFSK inlvl: 6% slot0 [slot1] RATE 1/2 DATA
Sync: -DMR mod: GFSK inlvl: 7% [slot0] slot1 RATE 3/4 DATA
Sync: -DMR mod: C4FM inlvl: 6% slot0 [slot1] RATE 1/2 DATA
Sync: -DMR mod: C4FM inlvl: 6% slot0 [SLOT1] F=1 VOICE e:================R======R========R
=======R=====R=====R===
Sync: (-DMR) mod: GFSK inlvl: 6% slot0 [SLOT1] F=1 VOICE e:====R=======R=========R====R=====
======R============
Sync: -DMR mod: C4FM inlvl: 6% [SLOT0] SLOT1 F=1 VOICE e:======R==========================
==R========R====R
Sync: (-DMR) mod: GFSK inlvl: 6% [SLOT0] slot1 F=1 VOICE e:===============R====T====R======R
==========R====R======
Sync: -DMR mod: GFSK inlvl: 6% [slot0] slot1 Unknown burst type: 1101

Is there a guide anywhere that would shed some light on what these various things mean? For example: what are the "R"s and "T"s in the VOICE lines? I've read that fewer "="s is better, but that's all I can find.

All of the audio, when someone speaks, is garbled and choppy. Completely unintelligible. According to other folks who monitor the system, privacy/encryption is rarely or never used.

I've tried:

* two different computers, one a MacBook Pro running Windows XP in VMWare Fusion and a real desktop PC running XP.
* adjusting the audio level so that "inlvl" is anywhere from 0% to 95%, with no apparent difference

My setup:

* E4000 USB dongle
* SDRSharp
* DSD 1.60 beta
* Virtual Audio Cable
* Roof-mounted ST2 antenna

Any ideas are welcome—both on interpreting the information that DSD is spitting out and why the audio is garbled.

 

[Dog]

From another post on the site.

From the DSD readme file:

"e:" is the beginning of the errorbars display. Each "=" indicates a
detected error within the voice data. "R" and "M" indicat that a voice
frame was repeated or muted due to excessive errors.

Link: http://forums.radioreference.com/di...e/227386-dsd-windows-port-12.html#post1770508

I don't know what "T" means.

I am very new with this (just got it working successfully last night. I was getting pretty much the same thing until I found a post listing "commands" for the type of system I was trying to decode.

Hope that helps some.

Here is a site I just found with some more information.

http://ukradioscanning.com/viewtopic.php?f=4&t=312

 

[alpharaysmax]

Thanks! My copy of DSD didn't come with a readme file - or anything other than the binary, actually. Just found a copy of the readme on Github. That's definitely helpful, at least to get a better understanding of DSD.

 

[Dog]

Could you post a link to the read me file? I have been looking for it myself. The 3 copies of DSD I have didn't come with it neither.

 

[alpharaysmax]

This may or may not be the latest version, but it's something - and I'm assuming this is specific to the Linux version and not the Windows port.

https://github.com/szechyjs/dsd/blob/master/README

I'm thinking at this point it may just be too weak of a signal to decoder properly. Which is hard to believe, but...

 

[Dog]

Thanks for posting the link. I have been looking for that for a few days.

 

[matthewn1983]

Try DMRDecode(Java) by Ian Wraith, it will display the traffic on the screen, if Privacy Enabled is displayed then you are out of luck.

 

[dtscho]

You may want to try this VAC alternative:

VB cable Archives - rtl-sdr.com

I was constantly getting garbled voice with VAC (even on non-privacy transmissions), and I switched to this, and now DSD works well.

Dave

 

[Tweekerbob]

I agree with the above poster.

More than likely, there is a mismatch is sampling rates or the number of audio channels (mono v. stereo).

See post #6 http://forums.radioreference.com/software-defined-radio/269569-help-sdrsharp-unitrunker-dsd.html for more info on how to set-up VAC to correctly decode the audio. Note, I have a Win 8 machine that uses slightly different settings, but I eventually got it to work. Or try VB Cable as was suggested and see if that is a better alternative.

 

[alpharaysmax]

You may want to try this VAC alternative

Just went and installed VB Cable, but I don't see any configuration options. Are there any? Out of the box, DMRDecode is reporting mostly errors (see below), and DSD is sitting completely idle.

CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:57:27 PM DMR Data Frame - Error !
CACH : TACT Ch 2 Continuation fragment of LC
4:57:27 PM DMR Embedded Frame - Error !
4:57:27 PM DMR Embedded Frame - Error !
CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:57:29 PM DMR Data Frame - Error !
4:57:29 PM DMR Embedded Frame - Error !
CACH : TACT Ch 2 First fragment of LC
4:57:30 PM DMR Data Frame - Error !
4:57:30 PM DMR Embedded Frame - Error !
CACH : TACT Ch 2 Continuation fragment of LC
4:57:32 PM DMR Data Frame - Error !
CACH : TACT AT=1 Ch 1 Last fragment of LC
4:57:32 PM DMR Embedded Frame - Error !
4:57:32 PM DMR Embedded Frame - Error !
CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:57:34 PM DMR Data Frame - Error !
4:57:34 PM DMR Embedded Frame - Error !
CACH : TACT AT=1 Ch 1 Last fragment of LC
4:57:36 PM DMR Data Frame - Error !
CACH : TACT Ch 2 First fragment of LC
4:57:36 PM DMR Embedded Frame - Error !
4:57:36 PM DMR Embedded Frame - Error !
CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:57:39 PM DMR Data Frame - Error !
4:57:39 PM DMR Embedded Frame - Error !
CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:57:42 PM DMR Data Frame - Error !
4:57:42 PM DMR Embedded Frame - Error !
CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:57:43 PM DMR Data Frame - Error !
4:57:43 PM DMR Embedded Frame - Error !
4:57:44 PM DMR Data Frame - Error !
4:57:44 PM Bad Short LC !
CACH : TACT AT=1 Ch 1 Last fragment of LC
4:57:44 PM DMR Embedded Frame - Error !
4:57:44 PM DMR Embedded Frame - Error !
CACH : TACT Ch 2 Continuation fragment of LC
4:57:45 PM DMR Data Frame - Error !
CACH : TACT AT=1 Ch 1 Last fragment of LC
4:57:45 PM DMR Data Frame - Error !
CACH : TACT Ch 2 First fragment of LC
4:57:45 PM DMR Embedded Frame - Error !
4:57:45 PM DMR Embedded Frame - Error !
Slot Type : Colour Code 1 Idle
CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:57:51 PM DMR Data Frame
CACH : TACT Ch 2 Continuation fragment of LC
4:57:51 PM DMR Embedded Frame - Error !
4:57:51 PM DMR Embedded Frame - Error !
4:57:52 PM Bad Short LC !
CACH : TACT AT=1 Ch 1 Last fragment of LC
4:57:52 PM DMR Data Frame - Error !
CACH : TACT Ch 2 First fragment of LC
4:57:52 PM DMR Embedded Frame - Error !
4:57:52 PM DMR Embedded Frame - Error !
CACH : TACT Ch 2 First fragment of LC
4:57:54 PM DMR Data Frame - Error !
CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:57:54 PM DMR Data Frame - Error !
4:57:54 PM DMR Embedded Frame - Error !
CACH : TACT AT=1 Ch 1 Last fragment of LC
4:58:00 PM DMR Data Frame - Error !
CACH : TACT Ch 2 First fragment of LC
4:58:00 PM DMR Embedded Frame - Error !
4:58:00 PM DMR Embedded Frame - Error !
CACH : TACT AT=1 Ch 1 Continuation fragment of LC
4:58:01 PM DMR Data Frame - Error !
4:58:01 PM DMR Embedded Frame - Error !

More than likely, there is a mismatch is sampling rates or the number of audio channels (mono v. stereo).

See post #6 ... for more info on how to set-up VAC to correctly decode the audio. Note, I have a Win 8 machine that uses slightly different settings, but I eventually got it to work. Or try VB Cable as was suggested and see if that is a better alternative.

I actually saw that post this morning - very helpful to see an actual working configuration, thanks! Unfortunately, I didn't notice any real difference in the resulting audio when duplicating those settings on my machine. (The interface is slightly different with my version of VAC but I think I managed to get all of the settings).

As far as mismatched sampling rates, etc., here's what VB Cable is reporting:

Input:
ch: 8
sr: 62500 Hz
res: 24 bits

Output:
ch: 1
sr: 48000 Hz
res: 16 bits

The sample rate in SDRSharp is 48000 Hz, but otherwise I'm not sure how I would change any of those settings if a change is even required. I don't see any options in the VB Cable control panel and there don't seem to be any relevant options in the Windows Sound panel either.

 

[moonbounce]

You may want to try this VAC alternative:

VB cable Archives - rtl-sdr.com

I was constantly getting garbled voice with VAC (even on non-privacy transmissions), and I switched to this, and now DSD works well.

Dave

Or instead of a VAC, this link maybe informative depending on your OS.

http://forums.radioreference.com/so...o-your-sdr-program-same-pc-picture-heavy.html

Moonbounce