DMR LCN Help

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dgoodson

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I am monitoring a six frequency DMR Tier 3 (trunked) system using 325P2. I do not know the LCN sequence for the system, and there are 720 unique possibilities.

In Trbo mode, I can id the frequency that provides the control channel, and if I monitor in conventional/digital mode I get an idea what frequencies are utilized the most.

Knowing this, and with no other tools than just the radio, is there any way to identify or even narrow down the possibilities for LCN?
 

Ubbe

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If you have LCN finder in the 325, enter all frequencies you suspect even the slightest to be part of the system and start the analyze. As soon as you see that two LCNs have been found you go to scan and save the result. Read the scanner and check which frequencies have got a LCN value.

Substract the lower LCN from the higher.
Substract the lower frequency from the higher and divide by the result from the LCN substraction.
The result are the stepsize for the bandplan.
Take one of the frequencies with a LCN and multiply the LCN with the stepsize and substract the result from that frequency to get the base frequency of the system.

Now take all the rest of the frequencies in the system and substract the base frequency from them and divide by the stepsize to get their LCNs.

This is only valid for Tier III systems.

/Ubbe
 

bheisner

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Thanks for the info on determining LCN. I'll give that a try.

Do you know if there's any good documentation for using LCN Finder on the BCD325P2?

Also, what is the maximum number of LCNs for Connect Plus and Capacity Plus DMRs?
 

wa8pyr

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Thanks for the info on determining LCN. I'll give that a try.

Do you know if there's any good documentation for using LCN Finder on the BCD325P2?

Also, what is the maximum number of LCNs for Connect Plus and Capacity Plus DMRs?
If you're using DSDPlus to visually monitor the system, you can try a trick developed by many people simultaneously back when trying to figure out the LCN layout on EDACS and LTR systems. . .

1. Park the DSDPlus monitor radio on the "rest" channel or "control" channel (whatever one is sending out channel assignment data, or a periodic beacon).

2. Program the site frequencies into an ordinary analog voice scanner.

3. While watching DSDPlus system activity on the computer screen, listen for which channel goes active on the analog scanner.

It may take a few passes to confirm a particular channel beyond reasonable doubt, but as you confirm each channel, lock it out on the analog scanner. Eventually you'll pin down the LCN layout.

This is easier to do on a weekend when there is activity, but not as much activity as you would see on a weekday. The preferred goal is one active voice channel at a time.

Finally. . .
Connect Plus systems can use a maximum of 15 repeaters per site. However, there is a maximum of 770 traffic slots, so for a 70-site system no more than 6 repeaters per site, and for a 250-site system no more than 2 repeaters per site).

Capacity Max (the new Motorola control-channel based system which uses the ETSI standard) can use a maximum of 250 sites with up to 15 channels per site. Limitations similar to Connect Plus probably apply.

Capacity Plus (single-site) and Linked Capacity Plus (multi-site) use a "rest" channel rather than a continuous control channel, maximum 1200 radios, up to 15 sites and up to 6 repeaters per site.
 
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bheisner

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Thanks Tom! Great Info!

I just order one of the RTL-SDR branded dongles and will be trying it out with DSD+ this weekend.
 

n9mxq

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This has me thoroughly confused. I'm using Proscan to track the history of a Local MotoTrbo Capacity Plus system. Watching the history on Proscan, I'm trying to match LCN #'s..Probably the wrong way, but I'm trying.

I've noticed the same frequency having 2 LCN's.. is this possible or am I not understanding something here?
 

n9mxq

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Should also state I'm using DMRDecode and an RTL stick to try and capture LCNs
 

UPMan

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Each frequency has two LSNs (logical slot numbers). To get the LCN for the channel, divide the higher LSN by 2 (i.e. if frequency has LSN 7/8, the LCN is 4).
 

n9mxq

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DMRDecode isn't showing LSNs. Only LCNs..
Code:
Activity Update : LCN 1 is the rest channel (Group 32 on LCN 2,Activity on LCN 6)
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  AT=1 Ch 1 First fragment of LC 
2:19:53 PM DMR Data Frame (BS)
Group Address : 3 Source Address : 40613
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  Ch 2 Continuation fragment of LC 
2:19:53 PM DMR Data Frame (BS)
Activity Update : LCN 1 is the rest channel (Group 32 on LCN 2,Activity on LCN 6)
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  AT=1 Ch 1 Continuation fragment of LC 
2:19:53 PM DMR Data Frame (BS)
Activity Update : LCN 1 is the rest channel (Group 32 on LCN 2,Activity on LCN 6)
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  AT=1 Ch 1 First fragment of LC 
2:19:54 PM DMR Data Frame (BS)
Group Address : 3 Source Address : 40613
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  Ch 2 Continuation fragment of LC 
2:19:54 PM DMR Data Frame (BS)
Activity Update : LCN 1 is the rest channel (Group 32 on LCN 2,Activity on LCN 6)
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  AT=1 Ch 1 Continuation fragment of LC 
2:19:54 PM DMR Data Frame (BS)
2:19:54 PM Short LC :  Capacity Plus Act_Updt - Rest Channel is LCN 1
Group Address : 3 Source Address : 40613
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  Ch 2 Last fragment of LC 
2:19:54 PM DMR Data Frame (BS)
Activity Update : LCN 1 is the rest channel (Group 32 on LCN 2,Activity on LCN 6)
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  AT=1 Ch 1 First fragment of LC 
2:19:54 PM DMR Data Frame (BS)
Group Address : 3 Source Address : 40613
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  Ch 2 Continuation fragment of LC 
2:19:54 PM DMR Data Frame (BS)
Activity Update : LCN 1 is the rest channel (Group 32 on LCN 2,Activity on LCN 6)
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  AT=1 Ch 1 Continuation fragment of LC 
2:19:54 PM DMR Data Frame (BS)
Activity Update : LCN 1 is the rest channel (Group 32 on LCN 2,Activity on LCN 6)
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  AT=1 Ch 1 First fragment of LC 
2:19:54 PM DMR Data Frame (BS)
Group Address : 3 Source Address : 40613
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  Ch 2 Continuation fragment of LC 
2:19:54 PM DMR Data Frame (BS)
EMB : Colour Code 1 : First fragment of LC 
CACH : TACT  Ch 2 Last fragment of LC 
2:19:54 PM DMR Voice Frame with Embedded Signalling
CACH : TACT  AT=1 Ch 2 Continuation fragment of LC 
2:19:56 PM DMR Voice Frame  (BS)
EMB : Colour Code 1 : Last fragment of LC
CACH : TACT  AT=1 Ch 1 Continuation fragment of LC 
2:19:56 PM DMR Voice Frame with Embedded Signalling
EMB : Colour Code 1 : First fragment of LC 
CACH : TACT  AT=1 Ch 2 Last fragment of LC 
2:19:56 PM DMR Voice Frame with Embedded Signalling
2:19:56 PM Embedded Single Block LC : Null
EMB : Colour Code 1 : Single fragment LC 
CACH : TACT  AT=1 Ch 1 First fragment of LC 
2:19:56 PM DMR Voice Frame with Embedded Signalling
EMB : Colour Code 1 : Continuation fragment of LC
CACH : TACT  AT=1 Ch 2 Continuation fragment of LC 
2:19:56 PM DMR Voice Frame with Embedded Signalling
CACH : TACT  AT=1 Ch 1 Continuation fragment of LC 
2:19:56 PM DMR Voice Frame  (BS)
CACH : TACT  AT=1 Ch 1 Continuation fragment of LC 
2:19:57 PM DMR Voice Frame  (BS)
EMB : Colour Code 1 : First fragment of LC 
CACH : TACT  AT=1 Ch 1 First fragment of LC 
2:19:57 PM DMR Voice Frame with Embedded Signalling
Group Address : 3 Source Address : 41037
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  AT=1 Ch 2 Continuation fragment of LC 
2:19:57 PM DMR Data Frame (BS)
EMB : Colour Code 1 : Continuation fragment of LC
CACH : TACT  AT=1 Ch 1 Continuation fragment of LC 
2:19:57 PM DMR Voice Frame with Embedded Signalling
2:19:57 PM Short LC :  Capacity Plus Act_Updt - Rest Channel is LCN 3
Group Address : 3 Source Address : 41037
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  AT=1 Ch 2 Last fragment of LC 
2:19:57 PM DMR Data Frame (BS)
EMB : Colour Code 1 : Continuation fragment of LC
CACH : TACT  AT=1 Ch 1 First fragment of LC 
2:19:58 PM DMR Voice Frame with Embedded Signalling
Group Address : 3 Source Address : 40613
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  AT=1 Ch 2 Continuation fragment of LC 
2:20:01 PM DMR Data Frame (BS)
CACH : TACT  AT=1 Ch 1 Continuation fragment of LC 
2:20:01 PM DMR Voice Frame  (BS)
CACH : TACT  Ch 1 Continuation fragment of LC 
2:20:15 PM DMR Voice Frame  (BS)
CACH : TACT  Ch 1 Continuation fragment of LC 
2:20:19 PM DMR Voice Frame  (BS)
EMB : Colour Code 1 : First fragment of LC 
CACH : TACT  Ch 1 First fragment of LC 
2:20:19 PM DMR Voice Frame with Embedded Signalling
Group Address : 6 Source Address : 40290
Service Options : Non-emergency/No priority
Group Voice Channel User LC
Slot Type : Colour Code 1 Terminator with LC
CACH : TACT  Ch 1 First fragment of LC 
2:20:22 PM DMR Data Frame (BS)
Activity Update : LCN 1 is the Rest Channel
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  Ch 2 Last fragment of LC 
2:20:25 PM DMR Data Frame (BS)
Activity Update : LCN 1 is the Rest Channel
Capacity Plus CSBK : CSBKO=62
Slot Type : Colour Code 1 CSBK
CACH : TACT  Ch 2 Continuation fragment of LC 
2:20:25 PM DMR Data Frame (BS)
CACH : TACT  AT=1 Ch 2 Last fragment of LC 
2:20:28 PM DMR Voice Frame  (BS)
2:20:28 PM Embedded Single Block LC : Null
EMB : Colour Code 1 : Single fragment LC 
CACH : TACT  AT=1 Ch 1 First fragment of LC 
2:20:28 PM DMR Voice Frame with Embedded Signalling
EMB : Colour Code 1 : First fragment of LC 
CACH : TACT  AT=1 Ch 2 Continuation fragment of LC 
2:20:28 PM DMR Voice Frame with Embedded Signalling
 

n9mxq

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So when is says Rest channel is LCN 9, it means 4? (Man this new math sucks ;-) ) And LCN 3 would be 1.... I'm getting a migraine...hehe
 

UPMan

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LCN 9 means 5, not 4.
LCN 3 means 2, not 1.

Slots are numbered starting with an odd number (i.e. 1, 3, 5, 7, 9...). So, the 2nd slot on the channel (the # you need to divide by 2) is always an even number (i.e. 2, 4, 6, 8, 10...).
 

n9mxq

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Ahhhhh Clear as mud.. So when it says activity on LCN 6... it's 3? Or stays 6? <bangs head on table>
 

n9mxq

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At this point I give up. With no clear way to get it narrowed down, I'll just stick to naming the talkgroups and call it good..

DSD+ Doesn't display anything about LCN/LSNs.. DMRDecode I can't be sure what it's telling me..

And the fact that DSD+ is decoding voice traffic that my 325p2 isn't even noticing...makes me want to scrap the whole project..
 
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