Couple of LTR Standard questions

[Airdorn]

I've been exploring LTR Standard systems using LTR-Analyzer and I've been having a great time. I had a couple of questions though.

1. I found a frequency that reports as LCN 1. When it does its morse code ID thing, it doesn't show any FREE LCN's, but instead shows only ATB (All trunks busy). It's always like this, day or night. It does the idle ping thing, too. Occasionally I'll hear conversations on it, and I'll see that it's reporting ATB again during the conversation. My question is, is this an LTR system with only a single, solitary LCN currently running on it?

2. Let's say there's an LTR system with 5 active LCN's, all 1 - 5 (for simplicity).. let's say that LCN 1 goes into use, and so it will report 2, 3, 4, and 5 as free. Now, if say, LCN 5 goes into use, would it necessarily report 1, 2, 3, and 4 as free (assuming none of them are busy), or is it possible for an LCN to NEVER report a certain other LCN or number of LCN's as free?

3. Finally, this concerns LTR-Analyzer itself. Is there a way to start the program from a desktop shortcut, and feed it the command to log to disk? I tried setting the desktop shortcut icon I made with the target as c:\ltr-analyzer >scanlog.log ... the program starts, but it apparently ignores the logging command using that method.

Thanks for any insight!

 

[pro92b]

There are a few single channel LTR systems here.

The LTR systems here do report all free channels from each LCN eventually. One company homes all users to LCN 1 and reports free channels on a rotating basis to even out transmitter wear. I believe the controller can be set to not report a given LCN as free if that's what the system administrator wants.

You can start the program from a batch file to enable logging. Maybe there is an easier way, but that's what I do.

@echo off
cls
c:
cd\
cd ltr-analyzer
ltr-analyzer /i >scanlog.log

The /i suppresses probable bad decoding. To append to the log instead of overwriting existing data, use >> instead of > to direct the data output.

 

[Airdorn]

*BONK!*

Forgot all about the ubiquitous batch file, thanks for the reminder.

 

[kb9hgi]

I have a question about LTR I have the frequencies for the system but how do you find out what the LCN is for each freq?

 

[captclint]

I have a question about LTR I have the frequencies for the system but how do you find out what the LCN is for each freq?

Without adding a discriminator tap, this should give you some guidance: http://wiki.radioreference.com/index.php/Mapping_an_LTR_System

 

[GrayJeep]

LTR mapping

I have a question about LTR I have the frequencies for the system but how do you find out what the LCN is for each freq?

In addition to the RR link, look back at a couple of my postings such as:

http://www.radioreference.com/forums/showthread.php?t=101160


One way to do it is to have a scanner that reports the system's LCN number on the channel when in Manual. The Pro-97 does this.

My 5th system was posted this weekend.

 

[Airdorn]

I have a question about LTR I have the frequencies for the system but how do you find out what the LCN is for each freq?

1. Get a list of all the system's frequencies via the FCC database. You can get it here, since this site gleans from the FCC database for you.

2. Print it out. Cross-out the frequencies that are not in an area near your area. Reject any of what's left with a CODE of FX1.

3. Of what frequencies are left, enter the first one on the list into your scanner and verify that you hear the short key-up that is characteristic of LTR systems.

4. Plug in your discriminator to your soundcard and load-up LTR-Analyzer. Watch what decodes. Hopefully you'll get IDLE messages with an LCN. Note the area code and the signal polarity.

5. Wait around for the CWID... the system should then reveal some if not all LCNs. Now you have another characteristic of the system: the order of the LCN's.

6. Make a list on a piece of paper from 1 to 20. Put that frequency on that LCN and also note the other LCN's next to it for later reference.

7. Go to the next frequency on your print-out.. if after 10 seconds or so you don't hear the characteristic key-up, reject it for now and go to the next freq.

8. When you find another freq that keys-up LTR-style, write it's LCN down and make a note of the signal polarity and the area code. If the signal polarity and area code are the same as the previous found LCN, then you still have a good candidate. If either are not the same, then save the freq for some other system search -- its not part of this one.

9. Wait around for the CWID again. It will reveal the other LCN's available. You can tell pretty quick if it is part of the system you are mapping. If it is, write the freq in its proper place on your sheet of paper.

10. After a while, as you go down your printout of the company's licensed frequencies, your list will fill up until all the numbers that "should" have frequencies DO have frequencies. (You know which numbers between 1 - 20 SHOULD be an active LCN because you saw the system reveal that information during CWID's and regular communications you might randomly pick-up.

11. Submit your newfound system to RR !

Beware of the random LCN decode that is all wrong, but looks ok... let the thing decode a few times to make sure you have the right data. I have found that sometimes, LCN's 'bleed-thru' onto other frequencies. You'll occasionally get a random COMM or CWID message for no good reason.

Also, eventually, you'll run into that one LCN you just can't seem to find. Keep trying for a while, but just give-up eventually. I think that even though some systems have LCN's assigned, they may not actually have a frequency stuck in there.

Another issue is the LCN's that don't seem to be 'open' to very many other LCN's, even though they are part of the same system. I'm not an LTR expert at all, but I can guess that whoever customer is assigned to that LCN may not have access to all the other ones, maybe as part of their contract or something. Maybe they chose the BASIC PLAN when they signed-up for service.

It's a long process, but the mapping is 2/3rds of the fun. Once you're done and actually start listening, you'll be hearing a bunch of rednecks towing cars and security guards that hate their jobs and are constantly *****ing about their 'relief' being late.

There are probably faster, more efficient ways of mapping LTR, but I like my way.

Good luck.

 

[kd5dga]

Airdorn,
I like your method discribed above. I'll have to keep that on my mind. I am trying to map out a system that only shows 3 channels.