Determining LCN w/780

[K5MAR]

OK, I know about the trick of programming a LTR freq into the first 20 channels of a bank on my 780, I've done that using the lowest freq licensed (the 780 is in Trunk, Search mode). I'm getting a morse ID every 30 minutes with an LTR ID of 00-17-253. But I can't figure out which channel the 780 is stopping on! I'm using ScanControl to log, and it only shows the TG, not the channel number. And I can't see any channel number on the display. I've tried hitting Manual, then Trunk, and keep getting a different channel number. Can anybody show me my error?

Mark S.

 

[pro92b]

Not sure I understand how you programmed the radio, but if the same frequency is in all 20 slots, you are hearing repeater number 17. The CWID always correctly identifies the repeater number.

 

[K5MAR]

I've set up the bank as LTR, and programmed the same freq in each of the first 20 channels. This should allow me to determine which LCN this frequency is, by seeing which channel is used when the freq becomes active. The so-called Uniden method, which doens't work with the GRE-designed scanners such as the PRO-92, which don't need the LTR freqs programmed in the LCN.

My problem is that I can't see the channel number on the 780 display, so I don't know which one is used.

Mark S.

 

[pro92b]

The CWID is group AHH253 where A is 0 or 1 (0 in your case) and HH is the home repeater number (LCN). If you saw 0-17-253, the LCN is 17. Unlike user talkgroups, the CWID (group 253) transmits only on its home repeater.

 

[K5MAR]

Not the way I understand LTR. The home repeater number is not the same as a frequency's Logical Channel number. In this location, there is one repeater, with five frequencies. All the frequencies are on repeater number 17, but the order they are in and on what channel has yet to be determined.

As a side note, the CWID is the FCC callsign, not the talkgroup or repeater number or the LCN.

Mark S.

 

[pro92b]

You don't understand LTR. LCN is a term that only applies to EDACS. Scanner users incorrectly apply it to LTR as well. The correct term for LTR is repeater number. For our purpose LCN = repeater number.

Any time a CWID is transmitted the talkgroup contains the LCN of the channel you are hearing. Program the frequency you are testing in slot 17 in the scanner and that channel should start picking up transmissions in ID search mode.

If we assume the other channels in the system are LCN 1, 5, 9, and 13, the CWID will be 0-01-253, 0-05-253...0-13-253 respectively. Catching a CWID is an absolutely sure way of determining the LCN of the channel being monitored.

 

[K5MAR]

Then why does the RR database list the LCNs for LTR systems, and why does my 780 manual say that to scan LTR systems you "Must program frequencies in exact order and location"? In fact, the RR Wiki on LTR Standard (here) says

Each subscriber radio must be programmed with all channels in the system in proper logical channel order (the same requirement as [[EDACS]] systems)

BTW: I locked out the channel corresponding to ch. 17, and the ID showed up anyway. And I've not heard any radio traffic on this channel all day long. Also the CWID is just the FCC callsign in Morse Code, which has nothing to do with LTR, EDACS, Motorola or any other type of trunking system. It's a common way for radio systems to ID, per FCC regulations. That same ID will show up on any radio frequency listed on that FCC license.

Now, it may be that I'm doing something wrong, and it may be that the LCN for this freq is 17. But nothing I've been able to do has confirmed this, and I'd like someone who is knowlegable about Uniden scanners, especially the 780, and LTR systems to explain to me the proper procedure, so I can make sure of what I'm doing.

Click-buzz

Mark S.

 

[K5MAR]

Thanks to the peson who emailed me with the info on how to get the channel number displayed when doing this search. He asked me not to tell, but you know who you are! THANKS! Got the system nailed!

Mark S.

 

[RoninJoliet]

On the Uniden 898T base scanner when i press the "LIMIT" button in the LTR bank in the search it shows me the freqy being used by the ID shown on the seven freqy ABEEP LTR system. Does the same thing for Edacs and Motorola systems and they did not even put it in the manual. Other posts are correct as it is usually called a LCN and usually the second and third digit state the proper bank LCN. .....

 

[2wayfreq]

Hi,
Can you do the same type of order search for EDACS? I havent searched for thr topic yet. Our sheriffs have some area systems where the exact LCN order is not known. I have a pro-96 and a pro-92. How could I set this up? Thanks

 

[DaveH]

Hi,
Can you do the same type of order search for EDACS? I havent searched for thr topic yet. Our sheriffs have some area systems where the exact LCN order is not known. I have a pro-96 and a pro-92. How could I set this up? Thanks

The PRO-92 can help you map out EDACS LCN order with the help of another
scanner (conventional). Park the 92 on the EDACS control channel (programmed
in ED mode of course). When idle, the CC's LCN is displayed (CTL-xx where xx is
the LCN) If the CC rotates, you can pick off the LCN's of those frequencies.

Pick a quiet time when few TG's are cycling through the system. Program the
channels into the other receiver and sit on one of them. When there is only one
group active, the 92 displays the LCN and the TG number active at the time (in
decimal). If there are multiple users, the display flips around and can be
confusing. Correlate it to the frequency on the other scanner. You could try
scanning the channels on the conventional scanner (lock out the CC). Repeat for all
other channels. Unless some channels are not assigned (may be out of rotation
being serviced at the time), you will get the complete LCN ordering.

Dave