Found Control Channel using close call

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dons1957

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I have found control channels using close call. If I find a control channel for a trunk system and want to set up a system for it so i can scan it, how do I know what type of trunked system to set up to place it in?
 

Jay911

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Go to this web page - Digital Modes Samples - and compare the sound you're hearing to the sounds for various trunking protocols (search for the word 'trunk' in the page, or just navigate to about halfway down).

Welcome to what I consider the most fun part of scanning. :)
 

dons1957

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Thanks Jay! I'm new to trunking. I always had a scanner, but now everything is going digital and trunk. This is a whole new world now. You can't be casual anymore. :)
 

Jay911

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What can you actually get out of scanning a trunked system?
Well, besides regular conversations for any kind of radio operation you can imagine (everything from public safety to business to media outlets etc), I particularly find it very entertaining to try to "sleuth out" all the bits and pieces of the trunk system - the talkgroups (channels in use), the data behind the system (the "system ID" which identifies the trunk system, for example, along with the frequencies in use, etc), and so on.
 

dons1957

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Once I place the control channel into a system, will it then populate the system with necessary frequencies? If so, can I scan it like that? Or do I have to place the frequencies into groups?
 

Jay911

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It depends on the trunk system. Most of the systems that you can monitor with a scanner - Motorola Type I, Type II, and APCO P25 - will work in your scanner with what is called "Control Channel Only". That means all you have to do is program in the channel you hear the data sound on (and optionally a couple other channels, especially if the data sound "rotates" between the channels on a regular basis), and it'll do the rest.

Other systems, particularly EDACS and LTR trunk systems, require frequencies to be programmed in a specific order in the scanner. This is called Logical Channel Numbering order or LCN order. If you don't know the proper LCN order of a system, figuring it out can be a little difficult, unless you have a scanner with the "LCN Finder" function. Since you mentioned Close Call, I'm betting you have a Uniden 396XT or 996XT, which doesn't have LCN Finder. In that case, if you have a truly undiscovered EDACS or LTR system that you need to determine the LCN order on, you have a few options, but it can be done (with some effort).

One thing I forgot to mention above is base, step, and offset details. In some Motorola and other trunk systems, you need to program these values so the scanner knows where to begin to "look" for the trunk signal (other than on the control channel you give it). If the system is in the 138-174 or 406-520 MHz bands, you might need to figure out these "band plan" values.

This Wiki article will help understand trunk systems: Trunked Radio Systems - The RadioReference Wiki - and there are a couple links near the bottom which explain discovering LCN order in LTR systems, etc.
 

dons1957

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Again, thanks so much for the quick response. It sounds like you have to be a real AFICIONADO such as yourself if you want to get into it that deep. And you are right! I just got the 996XT for Christmas. It looks pretty full featured, but probably would not be enough for somebody with your back ground. Right now, I have basic functions working and am hesitant to mess with it too heavily so that I don't screw things up. I need to spend some real quality time with it before I get real deep with it.

Again....Thanks! :)
 

ka3jjz

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Really dumb question follows - did you check the database to see if what you found corresponds to any system that's currently there? Since you're a premium subscriber, you can even check the FCC records...best regards..Mike
 

dons1957

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Well, nothing is a dumb question. I'm a total novice. The way I think the system works is that it checks to see what frequencies you currently have stored on yours system and only saves if it is unique. Thanks for the inquiry though.
 

BeerNutz

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With your new scanner, RR premium subscription and the freeware programming software called FreeScan you can program your radio and all systems, control channels and custom tables will be set with nothing to figure out.
 

DickH

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Once I place the control channel into a system, will it then populate the system with necessary frequencies? If so, can I scan it like that? Or do I have to place the frequencies into groups?
The control channel sends a stream of data to your scanner telling the scanner which freq. to tune to for the Talk Group being used.. When the other person talks, it follows that Talk Group and it may direct the scanner to another freq. to continue the conversation.

"... The way I think the system works is that it checks to see what frequencies you currently have stored on yours system and only saves if it is unique. .

NO. It works as described above. The only freqs. you need in your scanner are the control channel freqs.
 

dons1957

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That is partially correct from what I understand. The hard part is that if it is not a motorolla system, it will not find the other channels. Also, you have to determine which type of trunk system it is. I could be wrong though. I'm also just learning myself.
 

ScannerWayne

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Lol

The control channel sends a stream of data to your scanner telling the scanner which freq. to tune to for the Talk Group being used.. When the other person talks, it follows that Talk Group and it may direct the scanner to another freq. to continue the conversation.

"... The way I think the system works is that it checks to see what frequencies you currently have stored on yours system and only saves if it is unique. .

NO. It works as described above. The only freqs. you need in your scanner are the control channel freqs.
Yeah.. That's what my dad thought... He had his scanner (GRE-800) for about 3 months when he called me to say that the county system wasn't being received. I went over there and after a learning a little bit about the scanner programmed all the freqs for the system into the scanner. Worked fine after that.

What had happened? The store he had bought it from had programmed the scanner for him before shipping it. The data came straight from RR. They had only loaded the control channels into the scanner. Eventually the system switched to an undocumented Control Channel and the system no longer could be received.

Using only the Control Channel will cause you problems when you least expect it. It's fine to start with, but take the time to get all the system freqs into the scanner so that you aren't left hanging just when something interesting is going on.

Wayne...
 
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