Java program to decode DMR

[SCPD]

Ian;
3/4 rate trellis is supposed to be half rate trellis with half the parity bits thrown away. You may be able to feed 3/4 rate trellis data with pad bits into your half rate trellis decoder. It will correct the errors introduced by the pad bits plus any transmission errors.

 

[jeremym70]

Hello
Looking at your screenshot where a sync sequence but nothing else is being acquired the problem has to be a distorted DMR waveform. This is usually for one of two reasons ..

1) The signal you are monitoring is amazingly strong and is overloading your receiver.

2) There is some kind of a problem with your discriminator tap. I have come across a couple of users with similar problems in the past. Looking at their waveforms they appear to have what I can only describe as a partial discriminator output. It looks as though it is partially being processed somehow. As Forts said this might work with 3600 baud but isn't good enough for 4800 baud signals like DMR,

Also one last thing. You are monitoring the base output side of a DMR repeater aren't you ? DMRDecode won't work with simplex or mobile input sides of DMR signals.

Sorry I can't help more.

Regards

Ian

Ian,
Thanks for the info, I am definitely monitoring the repeater output and the signal should not be too strong. It is 10-15 miles away, so the problem is probably my output. I will do some more tweaking with it.

 

[IanWraith]

Hello

Ian,
Thanks for the info, I am definitely monitoring the repeater output and the signal should not be too strong. It is 10-15 miles away, so the problem is probably my output. I will do some more tweaking with it.

Do you know anyone local who also has a scanner with a discriminator output which you could try ? The problem is either going to be with your discriminator output or your sound cards line input circuitry.

Regards

Ian

 

[riveter]

In re the question for me, it's currently an IP site connect single-repeater-single-channel(per site) system with two towers. We have 6 freqs though, and I believe it is slated to become a Cap Plus system sometime over the next year or so as more departments at UMBC jump on.

 

[IanWraith]

Hello

In re the question for me, it's currently an IP site connect single-repeater-single-channel(per site) system with two towers. We have 6 freqs though, and I believe it is slated to become a Cap Plus system sometime over the next year or so as more departments at UMBC jump on.

Thanks. I see lots of rate 3/4 data PDUs on a local Cap Plus system here and had just presumed they were GPS fixes but am starting to wonder if some of them might be text messages now.

Regards

Ian

 

[IanWraith]

Hello

Ian;
3/4 rate trellis is supposed to be half rate trellis with half the parity bits thrown away. You may be able to feed 3/4 rate trellis data with pad bits into your half rate trellis decoder. It will correct the errors introduced by the pad bits plus any transmission errors.

Thanks for that. There is the added complication that 3/4 rate PDUs in DMR have their own interleaving method which I need to sort out before anything else.

Regards

Ian

 

[riveter]

Hello



Thanks. I see lots of rate 3/4 data PDUs on a local Cap Plus system here and had just presumed they were GPS fixes but am starting to wonder if some of them might be text messages now.

Regards

Ian

I've seen a few float past, and I don't think most of our guys have figured out texting so that confuses me given we don't have GPS in any of our portables.

BTW if it would help to have more material to play with, about next friday or so I can produce more of the same sort of logs.

 

[jeremym70]

Finally got it to work, problem was discriminator tap as Ian and others said. I replaced cap with a 10K resistor and it works great now.

It appears that most of the freqs in this area are a different sites and frequencies of a Connect Plus trunking system. Some frequencies seem to transmit all the time, but I never see any group calls, maybe they are a trunking control channel? I have found a few freqs associated with this system that intermittently transmit, sometimes with group individual or data transmissions. Sometimes those frequencies transmit, but nothing is decoded other than the color code and the Connect Plus site info. Any ideas on what that might be?

I have been able to take the info from DMR Decode and use it to program my XPR6550 to receive, now the fun begins to identify who is using it
Thanks!

 

[mtindor]

It appears that most of the freqs in this area are a different sites and frequencies of a Connect Plus trunking system. Some frequencies seem to transmit all the time, but I never see any group calls, maybe they are a trunking control channel? I have found a few freqs associated with this system that intermittently transmit, sometimes with group individual or data transmissions. Sometimes those frequencies transmit, but nothing is decoded other than the color code and the Connect Plus site info. Any ideas on what that might be?

The 24/7 channels are control channels of a Connect Plus. You may also hear channels that are very busy but which you rarely hear voice on... there is text messaging and, more often, GPS data being passed around. Typically lots of data on TRBO Connect Plus systems.

Is the system you are monitoring documented? If not, please start to document and submit the 24/7 control channels you are hearing and their Network ID. If you can figure out who owns the transmitters [by looking up the freqs in the RRDB FCC records] you can submit all that information and an admin will enter it in so that others in your area can monitor as well.

It's a lot of fun sleuthing out a Connect Plus system.

mike

 

[IanWraith]

Hello

Finally got it to work, problem was discriminator tap as Ian and others said. I replaced cap with a 10K resistor and it works great now.

That's good news. DMR monitoring (and Capacity Plus in particular) takes a little getting used to but is well worth the effort.

Regards

Ian

 

[yo3ggx]

Porting the app to Android

Hi Folks

DMRDecode build 61 is now available for download from the usual place ..

DMRDecode Download

Big new feature in this build is that it allows you to select your audio source from within the program. In addition if you save settings this build saves your audio source choice and then uses it when the program is restarted automatically.
..
Ian

Hi Ian,

There is any way to add selection for the output audio interface too?
I'm trying to use your app to decode a DMR signal received through a WebSDR server,
The WebSDR client does not allow to change audio out, so both WebSDR and your app tries to output the sound to the same default channel.

On the other side, I've developed an Android application named Pocket RXTX which is available for free in Play Store. I would be interested to add DMR support in my app, by porting your Java code to Android.

Thank you,
Dan

 

[IanWraith]

There is any way to add selection for the output audio interface too?

DMRDecode shouldn't be outputting any audio. Do you mean the sound that is coming in via your line in (or other sound source) coming out of your speakers ?

On the other side, I've developed an Android application named Pocket RXTX which is available for free in Play Store. I would be interested to add DMR support in my app, by porting your Java code to Android.

I don't know much about Android development I must admit. However DMRDecode does a bit of maths intensive DSP with a raised cosine filter and as such needs a multi core processor (or one that does threading). So I'm guessing you would need a pretty high end phone to cope with that. If you are interested all of the source code is on Github ..

https://github.com/IanWraith/DMRDecode

feel free to fork.

Good luck.

Regards

Ian

 

[jeremym70]

The 24/7 channels are control channels of a Connect Plus. You may also hear channels that are very busy but which you rarely hear voice on... there is text messaging and, more often, GPS data being passed around. Typically lots of data on TRBO Connect Plus systems.

Is the system you are monitoring documented? If not, please start to document and submit the 24/7 control channels you are hearing and their Network ID. If you can figure out who owns the transmitters [by looking up the freqs in the RRDB FCC records] you can submit all that information and an admin will enter it in so that others in your area can monitor as well.

It's a lot of fun sleuthing out a Connect Plus system.

mike

Mike,
Most of the MotoTrbo systems I am currently listening to are part of the TrboWest system I believe. TRBOWEST Digital Two Way Radio System Oregon and Washington
I see the same group ID's across multiple frequencies. Some are different site ID's, others are different frequencies with the same site ID. Apparently as the primary frequency gets busy it rolls off conversations to alternate repeaters? So far most of the users I have found are not too exciting -- buses, taxis, trucking companies, street sweepers, security. Found about 15-20 active frequencies from my listening post.

 

[mtindor]

Mike,
Most of the MotoTrbo systems I am currently listening to are part of the TrboWest system I believe. TRBOWEST Digital Two Way Radio System Oregon and Washington
I see the same group ID's across multiple frequencies. Some are different site ID's, others are different frequencies with the same site ID. Apparently as the primary frequency gets busy it rolls off conversations to alternate repeaters? So far most of the users I have found are not too exciting -- buses, taxis, trucking companies, street sweepers, security. Found about 15-20 active frequencies from my listening post.

Jeremy,

I don't want to hijack this thread. But, if the TrboWest system isn't in the RadioReference database (and it doesn't look like it is -- I didn't look real close though), then please submit your findings to an appropriate county where you know one of the transmitters is active and ask an admin to start the process of getting that trunked system created.

In DMRDecode you should be able to see the Network ID show up on one of the lines. If you could submit the Network ID (which should be the same for all TrboWest) and then any/all active control channels you've found, the process can be started for an admin in that area to start populating the DB with info.

If you would like to dialog with me about this, feel free to PM me.

Thanks!

Mike

 

[scannerfreak]

Need some help from you more advanced guys

I had a new freq. recently start using what I thought was NXDN based on the FCC license. I ran DMRDecode on it just to see what it would decode and got the following:

12:12:59 AM DMR Data Frame
CACH : TACT Ch 1 Last fragment of LC
Slot Type : Colour Code 1 CSBK
Preamble CSBK : Data content 4 Blocks to follow
Target Address : 64250 Source Address : 407
12:12:59 AM Short LC : Act_Updt - Individual data activity on BS time slot 1 Hashed Addr 126 : No activity on BS time slot 2
12:12:59 AM DMR Data Frame
CACH : TACT AT=1 Ch 2 First fragment of LC
Slot Type : Colour Code 1 Idle
12:12:59 AM DMR Data Frame
CACH : TACT Ch 1 Continuation fragment of LC
Slot Type : Colour Code 1 Data Header
Confirmed Data
12:12:59 AM DMR Data Frame
CACH : TACT AT=1 Ch 2 Continuation fragment of LC
Slot Type : Colour Code 1 Idle
12:12:59 AM DMR Data Frame
CACH : TACT Ch 1 Last fragment of LC
Slot Type : Colour Code 1 Data Header
Proprietary Data : MFID=16 (Motorola)
000100010000000100000000000000000101011100011010
12:12:59 AM DMR Data Frame
CACH : TACT AT=1 Ch 2 Continuation fragment of LC
Slot Type : Colour Code 1 Idle
12:12:59 AM DMR Data Frame
CACH : TACT Ch 1 Last fragment of LC
Slot Type : Colour Code 1 Rate ¾ Data Continuation
0010111011111101111010101011001000100010101111010111001001001000111111000111001000100010110100110100000110101000100110101101001000100010111001010000101011010101010101001101001000100010110111100111

Anyone ever seen the bold part of the above decode before? I can't recall seeing that on anything in DMRDecode before, but I could just not remember seeing it. I take it this is TRBO? DSD won't decode anything in -fi mode, but will try to decode in -fr mode. I think it's using privacy as it sounds encrypted.

 

[grosminet]

maybe Mototrbo network with trbonet

Hello from france and sorry for mistakes

Target Address : 64250 Source Address : 407

64250 is the address of the dispatcher . This is a solution that can monitor, records and manage calls , talkgroups . This is a windows solution based on IP and connected to a DR3000 . DMRdecode can see all conversations as DMR data but it is DMR voice (could be encrypted !!)

See informations on Home - TRBOnet. Dispatcher Console, Data Application, IP Site Connect, Connect Plus, Capacity Plus, Telephone Interconnect, 800 mhz, MOTOTRBO software, motorola, GPS, telemetry, mototrbo system planner

here are some french networks example :

1 GROUP (Only used channel 2)
204 Group Calls only (Only used channel 1)
205 Group Calls only (Only used channel 2)
206 Data only
64250 Data only

hope help you

 

[Forts]

Need some help from you more advanced guys

I had a new freq. recently start using what I thought was NXDN based on the FCC license. I ran DMRDecode on it just to see what it would decode and got the following:

Proprietary Data : MFID=16 (Motorola)

Ian added that a little while ago... from what I've seen, in my area, the majority of the systems I've monitored do not broadcast it.

As far as the traffic being encrypted just log the activity for a while and check the log. During voice transmissions you will see something like:

Service Options : Non-emergency/Privacy Enabled/No priority

If the transmissions are in the clear you won't see the 'Privacy Enabled'

Oh, and yes... that's definitely a TRBO channel!!

 

[Forts]

TRBOnet is an expensive and rather involved alternative for the hobbyist... And I believe it needs to reside on the radio systems network to do it's job properly.

 

[scannerfreak]

Ian added that a little while ago... from what I've seen, in my area, the majority of the systems I've monitored do not broadcast it.

As far as the traffic being encrypted just log the activity for a while and check the log. During voice transmissions you will see something like:

Service Options : Non-emergency/Privacy Enabled/No priority

If the transmissions are in the clear you won't see the 'Privacy Enabled'

Oh, and yes... that's definitely a TRBO channel!!

Thanks for the help

Yes, this is the first one I have seen that has had the message in it. So most must not broadcast it.

I ran it for 8 hours and not once did the service options pop up like they normally do. I can receive all other TRBO traffic crystal clear on DSD, but when this channel pops up I get what I usually hear on the private channels on the capacity plus system I monitor that has both clear and private channels. I'll keep at it and see what happens

 

[Forts]

Did the log file summary show voice useage? If not the channel you are on may just be used for data (GPS and such)....