How to ID Trunked on FCC Database? (+Example)

[oregontreehugger]

I was going to post this to the specific state forum, but there doesn't seem to be much activity there.

I ran an FCC lookup in the database after finding a VHF frequency (151.7300 MHz) recently being used. I found the most likely source in the database, but it shows as a "Centralized Trunk Mobile" and "Centralized Trunk Relay." Is this truly some sort of trunked system? Or something else?

WPTF766

http://dettifoss.fcc.gov/acweb/dettifoss/Genmen_a/db_19/d_admin_l_lm.roi;29660?ViewDefault

Thanks!

 

[loumaag]

Umm, I am not sure what you are asking. The license shows it is an "YK" license which is "Industrial/Business Pool - Commercial Trunking" license. So assuming they are using the radios in accordance with the license, it is a trunking system.

As an aside, IMHO using the search engine you used is tedious and confusing, try using the ULS search engine, it seems to be easier to read and provides access to more informtion without drilling so hard.

Here is the link to the provided license ID using it:
http://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=2352152

If you start at this advanced search link, you will probably be happier in the future.

 

[oregontreehugger]

Thanks! That ULS advanced lookup site is much nicer.

Based on what you've said, it looks like I've stumbled across a new trunked system not yet on Radio Reference. Assuming they are using them as the license says.

Now that I know the frequencies, I guess the next fun part is trying to figure out WHAT type of trunked system it is. :shock:

I'll program the frequencies in and see if there's a control channel (hopefully).

 

[loumaag]

Hmm, just ran another search using the FRN as the lookup. This guy is a busy guy. :lol:

 

[INDY72]

Here are a few hints:

For the magority of Trunked Systems they have listed this as the service-
YO, YP, YF, YK, YG,.. etc...

The Y usually indicated trunking..... Though there are a few in the IG, and PW types that are actually trunking but not liscensed as trunked.. These are usually an LTR type of system, and often LTR Passport.

 

[oregontreehugger]

Well I plugged all the frequencies in as conventional in my BC246T to see what I could hear.

I didn't hear any typical Motorola-type control channel gibberish. But while scanning, on 151.580 and 151.730, about every 5-10 seconds the squelch breaks. There isn't any noise or data that I can hear, just the squelch opening.

Also, on 151.730 there was a quick morse ID at a separate time.

Ideas?

 

[INDY72]

LTR Standard TRS

What your hearing is the subaduible Data Bursts LTR uses instead of a CC for trunking.

 

[loumaag]

Could be Standard LTR. That is one explanation of the 10 sec. key up; however, Moto systems will also do that on voice channels. Does the 246 do LTR? (Too many models to keep up with. :shock: ) If so plug one of them in the first 20 frequency slots for (1-20) a bank, set it to LTR and wait for some traffic. See what it docodes to.

Also, as I said, use the FRN as a lookup and you will see that this is a pretty wide spread entity. Check the IG freq's on other licenses also to see if one of them is a control channel, as milf points out, there is a lot of slop when it comes to the FCC data.

 

[INDY72]

Yepper the BC246T will do LTR

In fact all of the modern Uniden BearCat's will do LTR....

Kinda took GRE a while to catch back up again with the upcomming PRO-97.


The only modern Unidens that do NOT do LTR are the SportCat's. And the only reason they don't is because there are not any LTR TRS's in use by NASCAR lol.

*That leads to an eventual other thread- portable mini TRS's for sports agencies..... ?Itenerant trunking? lol*

 

[oregontreehugger]

OK, I plugged in all the frequencies in as LTR.

However, I wasn't sure of the LCN. I went from lowest->highest frequency as LCN 1, LCN 2, LCN 3, etc.

[Edit: I just changed my programming to reflect what appears to be the 20W fixed base frequencies, only programming in the three base freq, and in the order the FCC site gave. I now am getting my first talkgroup of 0-01-152, possibly a security company or something. The scanner seemed to follow the transmission when I held on the talkgroup.]

[Edit Also: There appears to be 3 fixed base freqs, and 6 mobile freqs. Is there a reason for this? Is this typical of an LTR system?]

In viewing the FCC ULS data, there is a field for "Freq ID." I'm not sure if this is the LCN order I should use, or if it's simply a way of the FCC to keep track of all the frequencies assigned to this licensee.

Thanks again!

 

[loumaag]

NO, the FCC has no fields or any information about what kind of trunking system nor do they care. Nothing on the FCC database can be used to determine LCN order for any type trunking system that requires LCN.

That being said, you mis-understood what I said to do. Take one frequency and plug it into all 20 slots.

But, since you stumbled onto one, which seems to be in the right slot, leave it where it was (whichever one it was in whatever slot) and then take a second frequency (only one of them) and put it in the remaining 19 frequency slots. If you know which one of the two remaining are the most acitve, use it. Then when it lights up, you will know what slot it belongs in. This is how you figure out LCN's on a LTR system.

 

[oregontreehugger]

Only trouble is, running a BC246T, there aren't really banks or dedicated channel numbers. It has dynamic memory.

I think I see what you're saying though... I should go back to trying to monitor the system in conventional mode by scanning, and not attempt to program it in as a LTR with its associated LCN right now. Especially since I don't know the proper LCN.

Thanks for bearing with me. First LTR system.

 

[loumaag]

Only trouble is, running a BC246T, there aren't really banks or dedicated channel numbers. It has dynamic memory.

I think I see what you're saying though... I should go back to trying to monitor the system in conventional mode, and not attempt to program it in as a LTR with its associated LCN right now. Especially since I don't know the LCN.

Hmm, not quite. I really don't know enough about the 246 to speak intelligenlty on it, so let me explain what I mean as if it were not using dynamic memory. Then you will have to figure out how to make it work on the 246.

We will assume a 796d (since I have one of those). It has 10 banks of 100 frequencies. For an LTR system (which has a maximum of 20 frequencies per system) that I didn't know the LCN order I would pick a bank on the radio, take the most active frequency used on the system, and plug it into frequncy slots 1-20 of that bank in LTR trunking mode. Now only one of those 20 will ever work because it will be in its proper spot. Once I determine the proper spot for the first test frequency, I leave it in that slot and then replace the remaining 19 slots with the second most used frequency. Eventually that second frequency will sound off and I will know what slot it belongs. I continue this process for whatever remaining frequencies there are until I get them all (hopefully) figured out.

Now how that applies to the 246, I have no idea. But if all else fails, go find somebody with a Pro-92 or Pro-2067. Neither one cares what slot they go in, they will work no matter where you put them in those models. :lol:

 

[ericcarlson]

The 246T dynamic memory setup makes determining LTR LCN almost impossible. I saw a convoluted explanation of how to determine LCN with the 246T (check the 246T threads here or try Google) but it requires a lot of patience and button pushing.

There is a shortcut, however, if all of the channels in the system are used as home channels. You can sit on an LTR channel in manual mode with the 246T and it will display the current talkgroup ID when the channel becomes active. Once you have the order you can program the 246T properly.

-Eric

 

[oregontreehugger]

OK, that makes a little more sense to me.

And just so I'm sure what I'm doing, or unsure , we are only talking about programming in the base frequencies, right?

So in this case with three base frequencies, we're probably talking about an LTR system with three channels. My challenge is to find out what LCN order these three go in.

Or do I need to be worried about the channels listed as mobile, too?

 

[loumaag]

So in this case with three base frequencies, we're probably talking about an LTR system with three channels. My challenge is to find out what LCN order these three go in.

This is correct! :lol:

 

[ericcarlson]

And just so I'm sure what I'm doing, or unsure , we are only talking about programming in the base frequencies, right?

So in this case with three base frequencies, we're probably talking about an LTR system with three channels. My challenge is to find out what LCN order these three go in.

Or do I need to be worried about the channels listed as mobile, too?

Ignore the mobile-only channels, these are the inputs to the repeaters. Only program the repeater output (base) frequencies to track the LTR system.

-Eric

 

[oregontreehugger]

Thanks guys!

Thanks for bearing with me, too. Trying to go from 0->Unknown LTR in 60 seconds.

Any other tips greatly appreciated!

 

[ericcarlson]

I started an entry in the database for this system, please submit updates as you confirm information about this system.

http://www.radioreference.com/modules.php?name=TRSDB&sid=3858&d=rrdb

Also, be sure to review the LTR forum. There are many threads discussing how to make sense of LTR systems.

-Eric

 

[oregontreehugger]

Thanks... I was just about to submit the site.

I noticed on the listing you started it mentions "Site 002". Is there a particular reason it isn't called "Site 001"?