Understanding Connect Plus trunking

IanWraith · Dec 6, 2012

Hello All

I have just uploaded DMRDecode build 57 to the usual place ..

https://github.com/IanWraith/DMRDecode/downloads

Note that from this build onwards you will need to have Java 7 installed to run the program. To find out which version you have installed go to a command prompt and type "java -version" if you don't see something like "java version 1.7.0" or the program doesn't run then you need to upgrade. The upgrade can be downloaded from here ..

Oracle Java Runtime Environment 7u9 Downloads

Build 57 should decode the Connect Plus CSBKO 01 FID=6 PDUs but I can't test this so would be grateful if one of you could. Also what other changes are needed ?

The code changes can be seen here ..

https://github.com/IanWraith/DMRDecode/blob/master/src/com/dmr/CSBK.java#L231

Regards

Ian

inigo88 · Dec 6, 2012

Just spotted another unknown one: CSBK=10. It's in my screenshot in the DMRDecode thread.

W8EMX · Feb 4, 2013

After much studying of a local ConnectPlus system here, I determined that the next bit after the LCN group was a flag to indicate the timeslot on which the grant was issued (Motorola specifies in their documentation that the transmitted information to the subscriber includes repeater number AND timeslot informaiton)

A 0 in this field indicates Timeslot 1 and a "1" indicates Timeslot 2

I.E.

Code:

            Source                Group           LCN  TS
000000000000010001101010 000000000010001101000110 0100 0  00000000010  (Channel Grant : LCN 4  TS 1 Source 1130 Group 9030)
000000000000010001101010 000000000010001101000110 0100 1  00000000010  (Channel Grant : LCN 4  TS 2 Source 1130 Group 9030)
000000000000010001101010 000000000010001101000110 0101 0  00000000010  (Channel Grant : LCN 5  TS 1 Source 1130 Group 9030)
000000000000010001101010 000000000010001101000110 0101 1  00000000010  (Channel Grant : LCN 5  TS 2 Source 1130 Group 9030)

I made a few tweaks in my copy of the code to implement this and things chime along quite nicely, with each successive talkgroup walking up the LCN / TS step, just like most other Motorola trunking systems out there.

-_TS

Forts · Feb 4, 2013

Nicely done, thanks for sharing that!!

IanWraith · Feb 5, 2013

Hello
Many thanks for that information W8EMX. This has been incorporated into DMRDecode and a new build (59) is now ready for download ..

DMRDecode Download

I haven't been able to test this new feature so I would be grateful if someone could let me know it works OK.

The source code changes can be seen here along with the credits for who found this ..

https://github.com/IanWraith/DMRDecode/commit/b64a93b7a9c2f09025ee62997432b5da3c7e73b3

Thanks again.

Ian

inigo88 · Feb 8, 2013

Awesome job guys! Can't wait to test it out!

ericcarlson · Apr 7, 2013

I'm monitoring a new Connect Plus system in Houston. I'm seeing the CSBKO=18 and CSBKO=17 periodically on an otherwise idle system. Screenshot below.

radioprescott · Apr 9, 2013

Fisher wide area system

Is the network ID unique to a system or can it be reused in another state/region.

The reason I ask is that inigo88 reports Network 119 as a Fisher system in San Diego. I have a system here that reports:

Connect Plus Control Channel SLCO=10 Network: 119 Site: 72
Control Channel Neighbour List : 6,9,10,17,19 (0100011001001001010010100101000101010011000000000000000000000111)

The CC alternates between 461.8125 and 462.5250, but both freqs are licensed to Niles Radio on Squaw Peak near Camp Verde, AZ, not Fisher (The only actvity on the Fisher licensed freqs at that location are LTR and Passport systems).

I have not seen any voice grants on this system in a week of daytime montoring, (I work at home and left DMR Decode running all day), and no activity noted on the other licensed freqs for Niles at that site.

IanWraith · Apr 10, 2013

Hello John

Its most likely that the network ID can be set by who ever sets up the system so this type of ID is rarely unique. I'm not sure about the FCC on your side of the Atlantic but here in Britain their equivalent OFCOM has no interest in this type of identifier at all.

Regards

Ian

radioprescott · Apr 10, 2013

IanWraith said:
Hello John

Its most likely that the network ID can be set by who ever sets up the system so this type of ID is rarely unique. I'm not sure about the FCC on your side of the Atlantic but here in Britain their equivalent OFCOM has no interest in this type of identifier at all.

Regards

Ian

Thanks Ian.

inigo88 · May 9, 2013

radioprescott said:
Thanks Ian.

Hey John, I've been told the Capacity Plus Network ID is set by Motorola at the factory and can't be changed once it gets to the system admins. I could be mistaken though. I believe Forts would have more info. However if my recollection is correct, that would make the network ID more arbitrary and less unique. i.e. How many P25 conventional systems use NAC $293, simply because they have no desire to change it from the default. 119 may be a default network ID unless the subscriber requests otherwise. I've run across numerous Fisher systems around California and all are programmed with it.

mikewazowski · May 9, 2013

I think you're talking about Connect Plus not Capacity Plus. I've never seen a Capacity Plus system with a network ID.

From what I understand, the network ID is set by Motorola.

If you're seeing Network ID's on the Fisher system, than its Connect Plus and it makes sense that they all share the same ID.

Forts · May 9, 2013

radioprescott said:
The reason I ask is that inigo88 reports Network 119 as a Fisher system in San Diego. I have a system that reports:

Connect Plus Control Channel SLCO=10 Network: 119 Site: 72
Control Channel Neighbour List : 6,9,10,17,19 (0100011001001001010010100101000101010011000000000000000000000111)

Something seems odd there... Last I saw Connect Plus only supported 35 sites...

inigo88 · May 9, 2013

Yeah sorry, I'm referring to Connect Plus. (At least I got the thread right.

) Capacity Plus has no network ID that I'm aware of... Forts is right about the number of sites. Unless the Connect Plus firmware was upgraded recently?

Frozentech · May 11, 2013

inigo88 said:
Yeah sorry, I'm referring to Connect Plus. (At least I got the thread right. ) Capacity Plus has no network ID that I'm aware of... Forts is right about the number of sites. Unless the Connect Plus firmware was upgraded recently?

The latest ConnectPlus firmware (R1.3) is still 35 sites, 30 timeslots per site max.

EricCottrell · Nov 3, 2013

Hello,

I can not seem to get DMRDecode to decode without a lot of errors. So I am in the process of adding decoding and error correction to DSD. Just doing simple table driven error correction noticeably improves weak signal decoding. I noticed DMRDecode detects errors, but does not do any error correction.

I recently read a press release about a Motorola update that increases the maximum number of connect plus sites in a network from 35 to 70. I also read in the Connect Plus System Planner that Version 1 only supported 7 network sites, with site numbers 1 through 6 only assignable to RF sites and site number 255 assignable only to a Trident ECHO. This indicates to me that the site number had 8 bits from the start and the two unknown bits between the Network ID and Site ID are part of the Site ID.

The Boston area has alot of Connect Plus sites, and a few Capacity Plus systems. Two networks are on 900 MHz. I recently found two networks on VHF. I think the Network ID is twelve bits. I came across a newly installed system with a Network ID of 364. The SLCO in binary is 000101101100 00000001 0000.

It seems more reasonable to roll over at the 4096th system than the 256th.

73 Eric

IanWraith · Nov 4, 2013

Hello Eric & all

EricCottrell said:
It seems more reasonable to roll over at the 4096th system than the 256th.

What commands are you seeing the 8 bit network ID in ?

In DMRDecode the SLCO=9 ..

https://github.com/IanWraith/DMRDecode/blob/master/src/com/dmr/ShortLC.java#L256

and SLCO=10 ..

https://github.com/IanWraith/DMRDecode/blob/master/src/com/dmr/ShortLC.java#L292

commands have the required 12 bit network IDs already.

Regards

Ian

EricCottrell · Nov 5, 2013

IanWraith said:
Hello Eric & all

What commands are you seeing the 8 bit network ID in ?

In DMRDecode the SLCO=9 ..

https://github.com/IanWraith/DMRDecode/blob/master/src/com/dmr/ShortLC.java#L256

and SLCO=10 ..

https://github.com/IanWraith/DMRDecode/blob/master/src/com/dmr/ShortLC.java#L292

commands have the required 12 bit network IDs already.

Regards

Ian

Hello,

Yes, those commands. Thanks, it was not clear from the thread that the bit assignments had changed.

73 Eric

EricCottrell · Nov 8, 2013

Hello,

I have been doing some listening and decoding of a local Connect Plus system. I figured out a couple of messages. I eliminated duplicate frames in the folowing examples.

--Radio Affiliation--

Code:

CSBK          lb:1 pf:0 MtCon+ GoTo CId:00192A Grp:000032 LCN:3 Slot:B ?:00000000010   - Radio 0x192a on Group 0x32 assigned lcn 3 slot 1 on slot 0
VOICE Header  pf:0 Grp V Ch Usr Grp:0x000032 RId:0x001956                              - Standard group voice header radio 0x1956 talking on Group 0x32 on slot 1     
Voice frames"going back to two"                                                        - user talks on slot 1
TLC           pf:0 Grp V Ch Usr Grp:0x000032 RId:0x001956                              - Standard group voice terminator on slot 1
shortly after transmission ends this appears on slot 0
CSBK          lb:1 pf:0 csbko:011000 fid:00000110 data:000000000001100100101010 000000000000000000111000 0000000000000010 - Radio 192a affilates with Group 38
CSBK          lb:1 pf:0 csbko:011000 fid:00000110 data:000000000001100101010110 000000000000000000111000 0000000000000010 - Radio 1956 affilates with Group 38

Some users on the system have data terminals. I noticed this CSBK is used to tell a radio to go to a lcn and slot and receive data.

Code:

                                                       Radio ID                 Lcn  S
CSBK          lb:1 pf:0 csbko:000110 fid:00000110 data:000000000001101000011100 0010 1 00000001011000000000000000000000000

I noticed this data goto is used to send both data blocks and CSBKs to a radio.

--Data--

Code:

CSBK          lb:1 pf:0 MtCon+ Data GoTo RId:0017EB LCN:3 Slot:B ?:00000001011000000000000000000000000     - Radio 0x0017EB goto lcn 3 slot 1 for data
CSBK          lb:1 pf:0 Preamble 6 Data blks TRId:0xFFFCDA RId:0x0017EB                                    - Preamble on slot 1 indicating upcoming data
TLC           pf:0 flco:111101 fid:00000000 data:00000000111111111111110011011010000000000001011111101011  - Terminator for the preamble
DATA Header                                                                                                - Data Header (not decoded yet)
CSBK          lb:1 pf:0 csbko:001100 fid:00000110 data:000000000001011111101011 0000101100000000000000000000000000000000  - CSBK sent has the radio id as well
TLC           pf:0 flco:001100 fid:00000110 data:00000000000000000000000000000000000000000000000000000000  - Terminator for the CSBK

73 Eric

Forts · Nov 8, 2013

Great work Eric! Thanks very much for contributing that!

Understanding Connect Plus trunking

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