Trying to decode MOTOTRBO--Need lots of help

[W4UVV]

I think I can do that

Can you record a .wav sample of your discriminator output and post it here or post a link to it?

Ok....I installed Audacity on my XP desktop. I connected the unfiltered audio output from the R7000 to the "line in" on my desktop. Using Audacity I created somel MOTOTRBO recordings centered on 461.5135 mhz. The R7000 is an analog receiver. Is it required that I use an unfiltered audio output signal from a digital scanner? I attempted to modify my 996XT scanner for unfiltered audio but the "DISC" pc board location markings are inoperative. I don't wish to experiment trying other pc board tap points.

RR will allow only about 2 seconds of wav file to upload. I have renamed the "WAV" file to "TXT". Rename it to "WAV"

If anyone is interested send me an email to "w4uvv@amsat.org" and I will send the wav files I have recorded on different polarities to the return email address.

John
W4UVV

 

[W4UVV]

very confusing to me

Ok John, we are now making some progress.

From your post earlier with 4 sreenshots, I can clearly see that pictures 1 and 2 are decoding correctly as MotoTRBO with the CORRECT polarity. Pictures 3 and 4 are the WRONG polarity. How do i know this...because wrong polarity will sound like a constant machine gun of 'voice' decodes even though the data will be a mix of voice and data. For most MotoTRBO systems, the vast majority of packets sent are signalling data, not voice. For the correct polarity you will see lots of data (like RATE 3/4 DATA, CSBK, UNKNOWN TYPE etc etc) and relatively speaking little VOICE. I know it's confusing to begin with as the minute you get voice coming out of the speakers, you think you've cracked it. It took me several days to work out that I needed to change polariy in some cases. So you need to run as +DMR for this system on this PC. And just to clarify, in my experience the decision to use +ve or -ve polarity depends on the decoding scanner/PC combo, NOT the system you're trying to decode.

The bad news is that if you are running +DMR and you still hear 'parceled up' time segment decodes, you are more than likely decoding encrypted or Privacy enabled MotoTRBO. The way to find out for sure is to run this great java program from Ian Wraith: https://github.com/IanWraith/DMRDecode/downloads. You should be able to run this program at the same time as DSD.

There are lots of details here:
http://forums.radioreference.com/digital-voice-decoding-software/191957-java-program-decode-dmr.html

Note again there is an ability to invert the polarity in DMRDecode so you will need to get this right.
WRONG polarity decodes will show lots of the same message, something like:
<timestamp> DMR Voice FRAME
CACH: TACT Ch1 First Segment of CSBK

CORRECT polarity will show text including stuff like:
Slot Type: Colour Code x Idle
Short LC: Nul_Msg
Group Voice Channel User LC
Service Options: Non-emergency/No Priority
Group Address : x Source Address : x
etc

So when you see/hear VOICE decodes in DSD, what does DMRDecode say:
For group calls that don't have privacy enabled, you'll see something like:
Service Options : Non-emergency/No priority

With privacy it'll look like:
Service Options : Non-emergency/Privacy Enabled/No priority

If DMRDecode is too challenging for you, post a wav file of the raw capture of the TRBO signal and I'll try and unpick it from there.

Jim

ok...You did good at explaining one problem is I am not intimately familiar with digital modes therefore MOTOTRBO is a new subject and difficult for me to grasp everything you mentioned. Using Audacity I created a couple of MOTOTRBO wav files for 461.5135 mhz. If you could email me at
< w4uvv@amsat.org > I can send them for you to analyze further.

Pictures 1 and 2 were positive polarity signals. You are correct that most transmissions are system data.
I did not hear parceled time segmented mushy audio on the positive polarity only on the negative polarity.. The positive polarity audio although mushy was constant with no interrupts.

I will download the DMRDecode program and see what results I get.

 

[woodpecker]

Ok....I installed Audacity on my XP desktop. I connected the unfiltered audio output from the R7000 to the "line in" on my desktop. Using Audacity I created somel MOTOTRBO recordings centered on 461.5135 mhz. The R7000 is an analog receiver. Is it required that I use an unfiltered audio output signal from a digital scanner? I attempted to modify my 996XT scanner for unfiltered audio but the "DISC" pc board location markings are inoperative. I don't wish to experiment trying other pc board tap points.

RR will allow only about 2 seconds of wav file to upload. I have renamed the "WAV" file to "TXT". Rename it to "WAV"

If anyone is interested send me an email to "w4uvv@amsat.org" and I will send the wav files I have recorded on different polarities to the return email address.

John
W4UVV

The sample is too short, I've sent you an email.

 

[W4UVV]

MOTOTRBO/P25 Decode Success!!!!!!

Success at last! You guys(JHampton2000, ilgrant and woodpecker) are geniuses!!!! I cannot think of a lesser description. All your help and advice little by little helped me get successful reception. Andy's recommendation to increase the line in resistance made the difference.

Jerry helped me get better Audacity sample captures and Jim's examples of what good MOTOTRBO should look like and what bad MOTOTRBO looks like really helped educate me on a new area of monitoring.

Where has dsd been all my life? It is great! l love it! I know now the basic commands and how to use them.

I received excellent MOTOTRBO audio reception on 461.5100 mhz. positive and quickly tuning I received another excellent MOTOTRBO audio signal on 461.7885 mhz. inverted.

Curious I tuned vhf beginning at 150 mhz. Moving up the band I thought I heard a digital audio. Retuning I did hear audio....P25 audio! I was hearing the Dinwiddie Co., VA SO on a non-trunked frequency of 151.0850 mhz. On 154.4375 mhz. I heard the Dinwiddie Co., P25 F/R dispatch on 154.4375 mhz.
It gets better. Tuning several of the VA. vhf frequencies for the statewide digital STARS radio system I heard P25 audio on several active voice repeater systems.

Imagine MOTOTRBO and P25 reception not using a digital scanner or pc card! Amazing! Hopefully we all benefited now knowing what works! I know I did.

I cannot thank you guys enough for your time and unselfish assistance. If there ever is a Hall of Fame for digital reception experimeters you guys should be in it.

Again profound thanks for your patience for tolerating me trying various configurations. I hope I can keep in touch with youall in the future if I need help....which I probably will.

Sorry for the delay in not answering your earlier emails but I was testing and wanted to confirm my reception before responding.

My next project is to see if I can get my setup to work in XP.

John
W4UVV

 

[woodpecker]

Glad we could help, for anyone else having similar problems make sure your input to the sound card is not clipping, if it is add a pot or potential divider on the input.

 

[ilgrant]

Glad that we were all able to help, John. Give yourself a pat for not giving up!

 

[eaglehigh]

Hi all,

I've the same problem, the decoding give me SSB like voice.
Could i sent someone a link to the captured .wav file? but i would to do in private message, not on this post.

Could someone help me?

 

[W4UVV]

I'll try

I'll try. PM me and include a name, phone contact number and non-RR email address.

John

W4UVV

 

[eaglehigh]

Hi W4UVV,

I can not send you en PM, the site says :

"eaglehigh, you do not have permission to access this page. This could be due to one of several reasons:

Your user account may not have sufficient privileges to access this page. Are you trying to edit someone else's post, access administrative features or some other privileged system?
If you are trying to post, the administrator may have disabled your account, or it may be awaiting activation.
"

 

[W4UVV]

It appears you cannot send PMs because you have not created a user profile which you need to do. To save time send me the previously requested info now to my trash email account
< wj3921@hotmail.com >.

John

 

[eaglehigh]

Hi W4UVV,
I sent you an email, but perhaps it is in spam trahs of your hotmail account?

 

[W4UVV]

Sorry I cannot help you

Hi W4UVV,
I sent you an email, but perhaps it is in spam trahs of your hotmail account?

I received and responded to your email in which you stated you did not speak or understand much English and do not live in North America. Due to anticipated language barrier difficulties involving technical subjects I recommend you request help from someone who speaks your native language. Good luck.

 

[Tweekerbob]

Hi all,

I've the same problem, the decoding give me SSB like voice.
Could i sent someone a link to the captured .wav file? but i would to do in private message, not on this post.

Could someone help me?

Try "-xr Expect inverted DMR/MOTOTRBO signal" option on DSD. When the signal is inverted the decoded audio will sound like Darth Vader suffocating underwater.

 

[eaglehigh]

Hello,

Yes it try -xr, i try all explained in this post. Do you have an email account on which i could sent you a link to my mototrbo capture?

 

[Tweekerbob]

tweekerbob at gmail

 

[Tweekerbob]

The sample you sent does not contain any voice packets and is inverted, so do you the -xr option.

 

[Tweekerbob]

Also, where is this signal coming from? Directly from a discriminator chip on a scanner? I noticed that in between the data bursts there is no audio. If it is coming directly from a discriminator, there should be white noise in between signals.

 

[Tweekerbob]

Also, where is this signal coming from? Directly from a discriminator chip on a scanner? I noticed that in between the data bursts there is no audio. If it is coming directly from a discriminator, there should be white noise in between signals.

 

[eaglehigh]

The signal come from an RTL SDR : DVB T Black stick and the windows soft SDRsharp.

Then i play the wav file with audacity with a jack cable from output of the sound card (line) into input of the sound card (mic)

For you there is no voice in this sample? : because without -xr a lot of voice packets appears.

If i use -xr, there is no more voice packets, only a lot of unknown burst type : 1101

 

[SCPD]

In SDRsharp, turn off filtering in Audio options.