LTR Standard sites

[Darkstar350]

I heard somewhere that LTR Standard systems supposedly do not have more then one site

Is this correct? If so - then why do scanners allow for multiple sites on a LTR standard system?

 

[slicerwizard]

Not true. PassPort systems support networked (multi-site) LTR. Each site looks just like a standard standalone LTR site, but comms are carried across the network.

 

[EricCottrell]

Hello,

Passport and Multi-Net do not use the same protocol as Standard LTR. It can get confusing as I have seen sites that mix Standard LTR with Passport on some of the repeaters.

The basic LTR standard protocol is meant for single site systems, but various enhancements have been made over the years to add features like multiple sites and roaming. One such system is LTR-Net, which is backwards compatible with Standard LTR.
Logic Trunked Radio - The RadioReference Wiki

73 Eric

 

[slicerwizard]

Passport and Multi-Net do not use the same protocol as Standard LTR. It can get confusing as I have seen sites that mix Standard LTR with Passport on some of the repeaters.

I'm not referring to either PassPort or Multi-Net transmissions.

PassPort systems support LTR and PassPort operations on the same repeaters.

PassPort systems support standard (single site) LTR and networked LTR. It all looks like standard LTR - no site numbers are broadcast, no neighbour lists, etc. Subscribers have to manually roam from one site to the next.

 

[Darkstar350]

Ok so lets use this for example-
Take some LTR frequencies all owned by the same private radio company
Lets say theres 2 different sets of frequencies all at the same tower/location
For "site one" 471.100 is LCN 1 472.200 is LCN 2 and 473.300 is LCN 3
"Site 2" 471.200 is LCN 1 472.300 is LCN 2 and 473.400 is LCN 3
Now lets say it appears to be not quite a Passport system - the talkgroups are standard LTR XX-XX-XXX format - however some of the same talkgroups simulcast amongst both sites

Would such a system be considered a "LTR Net" system? Or is it indeed a Passport system?
I was under the impression that passport does not have the same TGID format as standard LTR and it is not trackable by any scanner...

 

[slicerwizard]

It is an LTR system (not LTR-Net, not PassPort), probably running on Trident Micro Systems PassPort controller hardware.

Note: The above assumes that you have already verified that the system is not broadcasting any LTR-Net messages. If such messages are present, you are dealing with LTR-Net, which would make this whole "LTR Standard" thread rather pointless.

 

[Darkstar350]

The system i have in mind is definitely not a run of the mill LTR system - even though the scanners read it as such
What you mentioned would make sense in this case - somewhat of a "hybrid" standard and passport system...

Not quite sure what messages your referring to - but i do know that it does morse code and im pretty sure some of the channels have the idle "burst"...

 

[DSheirer]

The system i have in mind is definitely not a run of the mill LTR system - even though the scanners read it as such
What you mentioned would make sense in this case - somewhat of a "hybrid" standard and passport system...

Not quite sure what messages your referring to - but i do know that it does morse code and im pretty sure some of the channels have the idle "burst"...

If you have an sdr, you can run sdrtrunk against the system. Setup a channel with an LTR Standard decoder, a second one with a Passport decoder, and a third one with an LTR-Net decoder, with all 3 channels set to the same frequency. Turn on logging and post the decoded message logs and we can help you interpret the results.

The only LTR-like decoder not supported is Multi-Net.

Denny

 

[EricCottrell]

Hello,

A LTR-Net site will have a high Repeater Number continuously transmitting. It was Repeater 20 on a nearby system. It sounds like an open mike, but it is sending the sub-audible LTR data. It is the backup home channel for the site and sends all the activity on the site.

73 Eric

 

[slicerwizard]

The system i have in mind is definitely not a run of the mill LTR system - even though the scanners read it as such

Ok, then this thread isn't about standard LTR. BTW, a scanner won't tell you ^%&@, unless it has a CC dump mode that lets you see the raw LTR messages.

What you mentioned would make sense in this case - somewhat of a "hybrid" standard and passport system...

There is no PassPort component - other than possibly being supported by PassPort-capable controllers.

Not quite sure what messages your referring to - but i do know that it does morse code and im pretty sure some of the channels have the idle "burst"...

To determine what flavour of LTR you're dealing with, you need to get some flat audio (unfiltered audio) from a discriminator tap or an SDR dongle and either run the audio through a decoder (LTR-Analyzer is very easy to set up and use) or upload the audio somewhere so someone else can run it through a decoder.

 

[Darkstar350]

I have used LTR analyzer to map out LTR systems
I suppose i will take some screenshots just to see if theres anything of intrest..

My original question was basically just to figure out if multiple multicast sites are "allowed" on a LTR standard system

 

[fwradio]

Passport controllers will do LTR and you can map talkgroups from one site to another. There are also other brands of networked LTR controllers out there. Bridgecom is a pretty common one. They will allow you to map LTR talkgroups from one site to another and extend coverage. Site selection is still done the old fashioned way, with a few exceptions.