Some LTR finesse needed

[GrayJeep]

I have the frequencies figured out for a busy LTR system.
I have listened enough to have the functions of 29 TGs figured out. There are at least that many more that I don't yet have enough listening time to know from their conversations.

But I have some TGID anomalies.

My understanding is that there can be no more than 20 home repeaters. Which suggests that the home repeater number should never be higher than 20.
But I have one TG of 0-23-143 that has enough traffic that I think it is legitimate.
I have also heard audio with 0-26-224 and spoken phrases in 3 different 22-xxx TGs.

I also have a few TGs showing home channel 00. That's certainly wrong, isn't it?

So I'm wondering if the Pro-97 is decoding correctly, or whether the system is transmitting the TGIDs cleanly, or whether there really can be TGIDs with numbers higher than 20.

Ideas?
(No I can't put LTRslicer into use here. My work location won't allow it.)

 

[dtscho]

LTR systems cannot have more than 20 home repeaters. I think your Pro-97 is simply decoding false IDs. It seems to be a common problem with scanners.

Dave

 

[BC_Scan]

0-23 + 0-26 don't jive with programming of the system, however if you hear voice , than that beats met, I have seen those type of talkgroups , however no voice on them , so I just lock them out when searching a new system.
also home repeaters should show 1-20 only ,I have never seen 0 , so unless there is voice then I would lock it out>
TGID aka channel number is from 02-250 ,
your 97 is ok, just remeber when logging channels only right down & figure out the one's with voice, another tip is if you hear the data burst (usually a modem or gps) that is sometimes one down or up from the channel, ie 0-01-246 pauls towing (245-247 data)

 

[GrayJeep]

LTR help

Thanks for the perspective guys.
Having seen invalid TGs now I'm kind of wondering how to report my findings. I know my admin will be happy to have such an extensive system reported but this uncertainty is a problem.

The way I've been operating is that once I mostly figure out what a TG is for I put an alpha tag on it and then lock it out so that the scanner won't waste time on it and I go on to listening for the next one.

I wonder if I might be getting incorrect decodes as the scanner tests for lockout. Many of the mystery TGs are adjacent to known TGs.
Thanks!

 

[jerk]

LTR systems cannot have more than 20 home repeaters. I think your Pro-97 is simply decoding false IDs. It seems to be a common problem with scanners.

Dave

I get this problem with weak signals, also I think interference will cause it.
Just ignore it and go on, or if unsure program it to see if receiving traffic, it usually won't happen meaning it's a false.

 

[GrayJeep]

Further cleanup

Some experimenting indicates that if I hear one of these TGIDs transmitting if I punch the Manual button quickly enough while the transmission is still up I can see the TG more accurately. In Manual the TG lockout doesn't function so it displays the truth.

I think these bogus ID's are an artifact of lockouts.

Now I need to catch them transmitting one at a time so I can weed them out.

I've identified 39 TGIDs on 17 channels now and have a probable 3 more true TGs once I weed out the bogus ones.

 

[BC_Scan]

17 channels, this is good , then likely it is a 20 channel system, what does your fcc license for this system show ? (how many freq's)
the other thing to bear in mind is taxi's & courier's commonly use individal id's for each unit (car/vehicle etc) so abc taxi might be 1-02-199 (dispatcher) cars are 1-02-200, 201
202,203,204,205,206-250 etc. this makes it appear that the system is larger than it looks. the last three freqs if they are there , might be for overflow only when two or more co's are on say 0-03-### and they both are txing at the same time , they will automatically go to the next freq that is not busy for them, thats why when listening to a busy ltr system i program list only the co's i wanna hear , such as security, and don't have to listen to the rest.

 

[GrayJeep]

My LTR system

17 channels, this is good , then likely it is a 20 channel system, what does your fcc license for this system show ? (how many freq's)
the other thing to bear in mind is taxi's & courier's commonly use individal id's for each unit (car/vehicle etc) so abc taxi might be 1-02-199 (dispatcher) cars are 1-02-200, 201
202,203,204,205,206-250 etc. this makes it appear that the system is larger than it looks. the last three freqs if they are there , might be for overflow only when two or more co's are on say 0-03-### and they both are txing at the same time , they will automatically go to the next freq that is not busy for them, thats why when listening to a busy ltr system i program list only the co's i wanna hear , such as security, and don't have to listen to the rest.

The FCC license shows 15 channels on one callsign, 1 channel on another, and 1 channel on another. You guys gave me great advice on how to figure it out by looking at the company's holdings.

I used a busy company's TGID moving across the channels to prove that the channels are all related.

When I submit the system list I'll just say TOWING for each towing channel. I've not got the endurance to figure out how many towing companies are using it.

The system has lots of concrete, rock & gravel trucks and some towing.
The two most unusual are a sod farm and an auto auction. The oilfield service was really a puzzlement to hear.

 

[letarotor]

NW0U,

If you have a discriminator tapped scanner, try running LTR Analyzer on the frequencies in the system. That should tell you for sure how many freqs are in use on the system and their correct LCN positions. I'm presently trying to identify all the frequencies in three seperate LTR system at a huge hospital complex. So far, I am missing one frequency in each system to complete the puzzle. They have mixed and matched freqs from different licenses and LTR Analyzer helped to sort them out. The FCC database has been little help in identifying the missing freqs and the systems were set up by a contract communications company. I suspect they are using some of their assigned freqs but who knows. I'm hoping that my trusty SCOUT will help, or Close Call, in finding the missing ones.

Mark

 

[GrayJeep]

More tools

NW0U,

If you have a discriminator tapped scanner, try running LTR Analyzer on the frequencies in the system. That should tell you for sure how many freqs are in use on the system and their correct LCN positions. I'm presently trying to identify all the frequencies in three seperate LTR system at a huge hospital complex. So far, I am missing one frequency in each system to complete the puzzle. They have mixed and matched freqs from different licenses and LTR Analyzer helped to sort them out. The FCC database has been little help in identifying the missing freqs and the systems were set up by a contract communications company. I suspect they are using some of their assigned freqs but who knows. I'm hoping that my trusty SCOUT will help, or Close Call, in finding the missing ones.

Mark

Thanks for the suggestion but I'm working on a system 50 miles from home. And I can't use the boss' computer or my own. Has to be done manually. I suspect I'm missing a freq or two and will have to leave it to someone else to find. This one is my 4th add to RR database.

 

[jerk]

Thanks for the suggestion but I'm working on a system 50 miles from home. And I can't use the boss' computer or my own. Has to be done manually. I suspect I'm missing a freq or two and will have to leave it to someone else to find. This one is my 4th add to RR database.

I don't know if this is the case here, but remember most systems leave some channels as simplex, and I'm finding some as individual repeaters, (don't know if same company yet, but suspect so as they are not in use as LTR), at least in my area.