LCN Order

[DonnieDog]

I know I know............I searched and still dont have an answer.............

I have been monitoring a Local Govt LTR System UHF 4 Freqs. I have tried one freq on first 20 freqs, tried 4 freqs with several different LCN setups. My problem is that im getting hits for one freq on different HHs (different channels). I dont understand, I work two blocks from the system im monitoring and live within 15 mins of the system so I know im getting a good signal. Also im getting HHs between 20 and 30 also, which I know is weird. Im using a 780XLT and a BC246T.

Thanks in advance.

[n4yek]

Originally Posted by DonnieDog

I know I know............I searched and still dont have an answer.............

I have been monitoring a Local Govt LTR System UHF 4 Freqs. I have tried one freq on first 20 freqs, tried 4 freqs with several different LCN setups. My problem is that im getting hits for one freq on different HHs (different channels). I dont understand, I work two blocks from the system im monitoring and live within 15 mins of the system so I know im getting a good signal. Also im getting HHs between 20 and 30 also, which I know is weird. Im using a 780XLT and a BC246T.

Thanks in advance.

Donnie, you need to tell them which system you are asking about:
I am thinking it is this one: Scanner Frequencies: Veterans Administration - Mountian Home Hospital Trunking System, , Tennessee
The hits you are getting on different Home channels, is there one that is dominant over the others? Meaning more hits than the others? If so start with the freq in the LCN slot.
Just a suggestion.
Danny

[DonnieDog]

That is the correct system and 407.8375 has the most traffic. Ive put it in as channels 1-20 and getting hits on several HHs on various channels. Thats on both the 780 and the 246. Thanks for the help

[silverbk]

Since the system hasn't been mapped out yet. I would try to get ltr-analyzer running.

http://www.radioreference.com/forums...-released.html

If you listen to the system in analog mode, you should hear the control packets going out about every ten seconds. This would be the home repeater. Most of the users will pop up here when the system is idle.

Most of the systems I have come across stagger their repeaters. ie 1,3,5,7 with 3 usually being the home repeater.

Good luck

[DonnieDog]

Gotcha, but all four freqs that are licensed have the data burst about every 4/5 seconds. How would I be able to tell which one was home? BTW neither one of my scanners are tapped...thanks for the help........keep it coming.......

Is it safe to say that the busiest freq of the four is more than likely the home freq??

[silverbk]

Originally Posted by DonnieDog

Gotcha, but all four freqs that are licensed have the data burst about every 4/5 seconds. How would I be able to tell which one was home? BTW neither one of my scanners are tapped...thanks for the help........keep it coming.......

Is it safe to say that the busiest freq of the four is more than likely the home freq??

When the system is idle, and a user keys up, he will always be on his home repeater.

[DonnieDog]

I am ready to pull what little hair that I have out. I have now done the 1 thru 20 same freq on my 780 and now im getting hits on a few different channels and some with HH beyond 20 (like 28 and 30)

All four of the system freqs have the same 5 second interval of the system activity.

I am no further along that I was when I started.

Grrrrrrrrrrrrr..

Thanks for any help.

[Jafo_the_Kid]

I have read that if I am not mistaken that channels above 20 could be a hybrid or one of the LTR mysteries that just happen. Wait till you have maybe results with more then 24 hours monitoring it.

Do you have a discriminator tap or able to put on in I do not know much of the BCT780 but LTR-Analyzer has been my best friend in trying to map the system up here. Real simple interface and works through your microphone and line input. (Mine is running on my laptop and the plug is the same hole and just tell it to treat this as my line in) That program even recognizes my usb external Turtle Beach sound card never tried it yet but it sees it.

Keep the hair of whats left tho just takes a little patience........ well I just keep telling myself that and I am only a week in on trying to figure this whole thing out.

[silverbk]

Don't let the discriminator tap hold you back. They are really easy and cheap to install. I did one on a Pro-96, it took about 5 mins and $10.00 of RS parts.

LTR analyzer makes looking at the system a breeze. Every transmission is logged, you will instantly if you are on the correct home repeater and talkgroups will immediately be logged.

I had some help with a pretty well documented system already, but radio companies and users make changes all the time. LTR analyzer changed everything. Now I have a log of every talkgroup actually being used.

I am not affiliated with LTR analyzer, despite my glowing endorsement, but it is certainly the way to go on an unknown system like yours.

[n4yek]

Donnie,
If you get HH above 20 then you are receiving poor data from the system. You need to either try to get a better signal or your signal might be receiving some multipath causing your scanner to interpret the ID data incorrectly. Try moving the radio to a different place or possibly the antenna if possible.

Also one other note, sometimes a scanner will throw an ID at you, if you are paying attention, when there isn't any activity at all when you are sitting on one frequency and not scanning. Usually this is when I see false ID's and they are usually above 20 on the HH.

[DonnieDog]

Im keeping a decent log at the homestead and at work. Im trying to compare them but not much at all matches. I am almost positive that 192 is for the VA Police but..........im getting several different HHs with the 192....Thanks again.

[silverbk]

Try putting in area 0, HH= 01 or 03 then 192 for the talkgroup with only the frequency that you suspect as the home repeater. See if the scanner will track it.

If the system is set up like 90% of the LTR systems out there it should track.

It is not uncommon to get what I call birdies. Even LTR Analyzer gets hits on non existent talk groups. But it is smart enough to count the packets so you can discount it when you view the logs.

[cg]

with the data key ups every 4 to 5 seconds, I would guess Passport. you can get garbage while using a decoding program with Passport

chris

[silverbk]

Any LTR standard system can have the idle strobes enabled. It only serves to tell the radios on the system when they are in range.

[inigo88]

Yes but the 4 to 5 seconds between idle burst + the garbage above LCN 20 data is a VERY common indication that you're listening to a Passport system.

It depends how consistently he is seeing the same talkgroups. Passport will put out very random talkgroup ID numbers (I can only speak for GRE scanners such as the Pro-97), so if you see the same ones consistently come back it is an LTR Standard system.

It may be a geographical preference, but I don't agree with home repeaters ALWAYS being LCN 01 or 03, it is totally the system administrator's preference between 1 and 20. For example, a local system here has home repeaters on LCN 09, 13 and 15.

While LTR-Analyzer is the best way to go (I just wish slicerwizard would make it do PASSPORT! Hint Hint? ), you can make it work the old way by programming the most active frequency into LCN 01 - 20 and trunk tracking it. Remember that EACH talkgroup may have its OWN home repeater on different LCNs! At a time when it's not that busy (i.e. sending multiple key-ups to free channels) observe a specific talkgroup: The entire format "A-HH-GGG" will be the same EACH time, A being Area Bit, H being home repeater LCN and G being group ID.

If you see this same talkgroup with the same HH (for home repeater number) showing up on ONE (and only one) LCN consistently, then the LCN number of the current frequency is the number indicated in the -HH- field of the talkgroup ID.

This gets really confusing when the system is busy, because when a home repeater is full and two talkgroups assigned to that home repeater key up at the same time, one is sent to a FREE channel. In that case, the talkgroup with the format "A-HH-GGG" talking on the free channel, the LCN number of that frequency WILL NOT BE the HH indicated in the talkgroup ID. However, the talkgroup forced to go to the free channel will return to the home repeater again as soon as it becomes available. The best way to minimize this issue is to listen when the system is moderately busy (busy enough to hear anyone) but not busy enough so that multiple talkgroups with the same home repeater are keying up on it at the same time. The better solution is, of course, tap the scanner and run LTR-Analyzer.

You said that you see -192 consistently, but the HH changes each time. How consistently? If you hear the same conversation between the same two people, and the talkgroup ID changes each time (for instance with HH-192, the HHs change each time), then you are hearing a Passport system. Unfortunately, Passport is not currently supported by any scanner.

Good luck!

Inigo

[DonnieDog]

Thanks, the 192 that appears as the ID 9 times out of 10 has a different HH and when it is discovered using the 1 thru 20 method, although im not getting but the first couple of words of the transmission.

Another helpful thing ive noticed is that on my 780 is with the trunking activity indicators. Ive tried to notice all that I can when the scanner stops on anything that breaks squelch/shows ID, that when it stops on one that most of the time two of the activity indicators are lit meaning two freqs are active. Im double guessing myself about the system having more than 4 freq although its usually not that busy to really need more than 4 of them.

Thanks again!!

[Searay]

Once I find a valid home channel, and the find the goto based on activity, is the goto channel usually the next in lcn order or can it be any of the 20 lcn slots?