WhatIsIt

[fast2okc]

Need some help--

I've been working on logging LTR systems in the Oklahoma City area and just about the time I think I have it figured out....................

I've come across a system that doesn't follow the same rules (as if there were such a thing :roll: ). Each channel has an LTR idle data burst every ten seconds. However there is no talkgroup data when the frequency becomes active (except on one frequency).

Is there any way to determine what type of system I have and then, is there any way to monitor it with a BC296D?

Thanks for helping the less informed.

--FAST 2

 

[ericcarlson]

It is probably a mixed standard/Passport system. Although, I think the idle data bursts on Passport systems are usually more frequent than every 10 seconds.

-Eric

 

[INDY72]

LTR Passport Data Bursts are between 2 and 4 seconds apart on all acitve repeaters,.... LTR Standard is between 8 and 10 seconds on all active repeaters. Not sure exactly how a "Hybrid LTR" would behave.... I have not monitored one yet that has both Standard, and Passport comms mixed. If your scanner is programmed correctly for a Standard LTR, you should get TG ID's flashing up.... At least the Non PP TG's.

If your running an Uniden Scanner, make sure you have the LCN's correct,.. for a GRE/Radio Shack,.. you should not have any issues as long as each chan is set to LTR mode.

 

[EricCottrell]

Hello,

It could be a Multi-Net LTR system and a Regular LTR system sharing the same site but I doubt it. It does appear to be a Passport system that has a Regular LTR Home Channel for the few users that do not need roaming across multiple sites.

I have seen a Passport system with Idle Bursts every second and one system where some channels were every 8 seconds. It seems to be a user-configurable item with a lot of latitude. 2 seconds seems to be a recommended value.

On the channel with the Regular LTR traffic see if the group id comes up as 253 during the CW ID. I noticed Passport systems setup for Regular LTR use group 255 for CW-ID. Group 255 indicates idle as well so I doubt the scanner will display it.

This is one reason why I modified Trunker to decode LTR. A scanner does not display complete information. LTRDump will give you more information and decodes Passport but it needs a discriminator tap in the radio and a low-pass filtered data slicer. I have not determined if the BC796/BC296 has an internal low-pass filtered data slicer you can tap like the BC780. You could try a regular data slicer but any tones or voice on the signal will disrupt LTR decoding.

I have come across a combination Passport/Regular LTR system used by Foxwoods Casino in Ct. So far it is mostly Regular LTR. I noticed on the channels used as Regular LTR Home channels it only sends Regular LTR and aside from the different group id for the CW ID, it is difficult to tell it is a Passport system. Other channels will send Passport during the CW ID. Passport uses the group id of 65535 (decimal) for the CW ID.

I suspect that Passport Home Channels only send Passport and the "Overflow" (not a home channel for either Passport or Regular LTR) channels can send either. I have not seen any mix of Passport and Regular LTR during a single transmission.

There is a trick in determining the repeater number or LCN of a Regular LTR frequency with an Uniden scanner. Set up the bank as LTR and put the same frequency in the first 20 channels of the bank set as LTR. If a Regular LTR transmission occurs then the scanner will jump to the first channel of the bank for Repeater 1, second channel of the bank for Repeater 2, etc. IF the Repeater number matches the home repeater of the id (For Example, Repeater 2 if the id was 0-2-140) then it is likely the Repeater Number of the frequency as well.

73 Eric

 

[INDY72]

Very cool trick Erric....

Theoretically that could be done on a PRO-92/2067..... if you don't use the alpha tagging and leave out known ID's in one bank.. as each repeater is keyed with the conversations,.. you'd see it pop up on that freq, as well as the TG ID... learning all the time...

 

[fast2okc]

Thanks for the help guys.....

I'll label it as a Passport/Normal system and keep working on it.

I don't think your LTR trick will work with a BC296D. Possibly they changed the screen on this model, but when searching Talkgroups on LTR systems, it displays the frequency but not the channel number.

I put the known LTR frequencies in the channels above 20, say channels 30-40. Then I put frequencies in channels 1-20 that will identify that channel--say 450.100, 450.200, 450.300, etc. Then I just watch where the scanner is trying to switch to.

If I can identify (or guess at) one, then I try it in that channel and cross my fingers.

I guess whatever works.:?

FAST 2

 

[ericcarlson]

From my experience doing this trick on the BC780XLT I believe you have to push "hold" when the talkgroup displays and then immediately hit "trunk" to take the scanner out of trunked mode, then the channel number will be shown.

-Eric