Understanding Capacity Plus trunking

[dasnps]

I'm not sure how many frequencies are associated with it at all. I was looking for another agency that migrated to TRBO, found them, but also found a few others, this being one of them. I'm just trying to figure out the rest. There are a bunch of other frequencies listed, but this is the only one of them with any activity that I've gotten.

 

[IanWraith]

Hello All

I have just been looking at the source code behind FLCO=4 LC and we have 4 bits that make up the LCN. This means it has 16 possible states numbered from 0 (which dasuriano is seeing) to 15. Now its quite possible that Moto number these from 1 to 16 in their software. Another possibility is that the system dasuriano is seeing is badly set up or that LCN 0 has some special meaning.

Has anyone else seen this ?

Regards

Ian

 

[inigo88]

I haven't seen it yet, sorry! Does anyone know if Capacity Plus was updated recently? I know that when they updated Connect Plus they increased the number of possible sites... Could they have done the same with Capacity Plus channels?

 

[Forts]

Cps doesn't allow for LCN 0.... So I'm not sure what that would be either.

 

[inigo88]

Cps doesn't allow for LCN 0.... So I'm not sure what that would be either.

Well that answers my question...

 

[dasnps]

So I had the day off today and decided to take a new look at that same system. I have to admit that this one is getting me confused. At one point, it shows the color code as 2, with an embedded color code of 13, I think. I've included the log file so someone else that might know more than me can take a look.

 

[Forts]

I'm really not sure what to make of your log file... It seems odd that there isn't more Capacity Plus entries, especially with the call activity. I would expect to see entries like:

(This is from an older version of DMRd so it may look a little different format wise...)

CACH : TACT AT=1 Ch 2 First fragment of LC
Slot Type : Colour Code 3 CSBK
Capacity Plus CSBK : CSBKO=62
Activity Update : Group 10 call on LCN 4
1110010000100000000010100000000000000000000000000000000000000000
11:13:25 AM DMR Data Frame
CACH : TACT Ch 1 Continuation fragment of LC
Slot Type : Colour Code 3 Terminator with LC
Group Voice Channel User LC
Service Options : Non-emergency/No priority
Group Address : 10 Source Address : 6118

I also don't see any entries showing which LCN is the current rest channel:

Slot Type : Colour Code 3 CSBK
Capacity Plus CSBK : CSBKO=62
Activity Update : LCN 4 is the Rest Channel

As far the the color code 13 goes, are you possibly getting interference somehow? The only time I've seen that happen is when the frequency I'm monitoring gets swamped by a paging site or something... Or, when I happen to be able to pull in two different TRBO systems on the same frequency (usually only happens in the summer with some good skip going on)

 

[dasnps]

I did think it was odd that I wasn't seeing more capacity plus indicators. I don't really know about interference, but I have been able to decode other frequencies without a problem. It is just this one. Right now, it is showing embedded colour codes 8,12,13,14 all in one voice calls, so something is definitely odd with it. I'm going to at least program the non-capacity plus info into my xpr tomorrow and hope that can narrow down something.

Sent from my Galaxy Nexus using Tapatalk 2

 

[IanWraith]

Hello

I have just been looking at the EMB Colour Codes and you are right this is very odd and something I have never seen before. The Colour Code has relatively simple error protection so its possible the odd bad value could sneak through but I doubt as often as we are seeing here. My suspicion is that there is something very wrong with either the setup or the firmware of the system controller.

Regards

Ian

 

[racingfan360]

So not sure if this helps, but in my early days playing about with DMRDecode on several Capacity Plus systems, I recall seeing some reporting multiple Colour Codes. These were on very weak signals, and by improving the received signal strength the 'feature' disappeared.

Jim

 

[dasnps]

If it helps, the site that I was trying to get the info of is close, but not on top of me. Usually shows 2-3 bars on my scanner. There is a different site for the same frequency licensed to a communications company two counties over that is building a TRBO system, but not as a TRBO license. I still am getting voice hits, including ones that appear to be conventional, yet my XPR does not unmute at all, so I am getting the sense that there is definitely something off with this one frequency. Everything else I've tried going after has worked without a problem.

 

[dtscho]

In reading over this thread, I'm still not clear - is it possible for DMRDecode to display the slot (1-2, 3-4, 5-6, etc.) for the frequency that the scanner is parked on, or is a second scanner needed to work out the channel order?

Thanks,
Dave

 

[inigo88]

One scanner is all you need. Capacity Plus works much like LTR, Control info is relayed during the voice call, not through a dedicated control channel. If you scan around and discover a voice call on frequency A and the software says it's LCN 1, then you can reasonably assume that LCN 2 will also be on frequency A. That's just the way Capacity Plus is set up (two LCNs per frequency).

 

[dtscho]

Thanks - I wasn't sure that the software always said the LCN of the current voice call. Some of the logs I've generated don't seem to have it, but maybe I had a weak signal or something.

Dave

One scanner is all you need. Capacity Plus works much like LTR, Control info is relayed during the voice call, not through a dedicated control channel. If you scan around and discover a voice call on frequency A and the software says it's LCN 1, then you can reasonably assume that LCN 2 will also be on frequency A. That's just the way Capacity Plus is set up (two LCNs per frequency).

 

[inigo88]

It does talkgroup interrupt the way LTR does. During the voice call, it will say "Radio ID: xxxx on Talkgroup ID: xxxx on LCN: xx." Then another message will say "All non-participating radios not on this talkgroup, change to the new rest channel on LCN yy."

Then if a second call starts happening on one of the other voice frequencies (while the current call is still in progress), it will say:

"Radio: xxxx, Talkgroup: xxxx on LCN: xx..... Radio: yyyy, Talkgroup: yyyy on LCN: yy... New rest channel is LCN zz."

This allows for priority scanning, so If your radio is scanning talkgroup xxxx, but the channel knob is on talkgroup yyyy, it will know to switch to LCN yy even though it wasn't on the rest channel yet to hear that channel assignment. Kind of make sense?

 

[inigo88]

Hey Ian (and Forts), just noticed some "DMR Voice Frame with Embedded Signalling" messages on my local Capacity Plus system. These aren't that common and I usually don't catch them in time (didn't have a log going), so this may not be the whole message. Any idea what to make of it?

This was seen interspersed between "CACH:TACT Ch 2 Continuation Fragment of LC" and "EMB: Colour Code 1: PI=1 : Single Fragment of LC" and similar type messages.

A voice call was going at the time on Group: 201, Source: 1775, LCN 01.

3:29:43 PM Embedded Single Block LC: 10000010011000100000100000101000
3:29:43 PM Embedded Single Block LC: 11000000000000110110010000000000
3:29:43 PM Embedded Single Block LC: 00000010000000000000000001100000

Any idea what this might be about?

Edit: Some of TRBO's popular features include text messaging and GPS location, and we haven't scratched the surface on that yet with DMRDecode.

 

[IanWraith]

Hello Inigo88 & all

I must admit I have never really investigated Embedded Single Block LCs. The DMR standard is huge and at the moment DMRDecode really only does the basics. I have investigated text messages thanks to a member of this list and we discovered the basics of how it works but have never really had the time to integrate those into the program.

So in short plenty left to do !

Regards

Ian

 

[inigo88]

Can you elaborate which frames are used for text messaging so I can keep an eye out for them? Are they the 1/2 and 3/4 rate data PDUs and data headers? I just went back and read some of the ETSI standard yesterday so that helped remove some of the mystery of DMR terminology.

According to the standard it sounds like Embedded Single Block LCs are included in the CACH for late joiners (once the call was already in progress), but it doesn't really elaborate beyond that. I believe the air protocol standard (ETSI TS 102 361-1) also says there are four embedded short LCs sent and I believe I only caught three of them.

Thanks again, build 59 is running great!

 

[IanWraith]

Hello Inigo and all
Moto at least send text messages in half rate data PDUs. Depending on the size of the message they can be strung across several such PDUs.

Regards

Ian

 

[ucmhunit703]

Linked Mototrbo Capacity Plus

Can a Linked Mototrbo Capacity Plus System have over 6 sites? Could there be sites in the hundreds to build a statewide system?

Thanks