Control freq. on CAP Plus

AlphaFive · Apr 10, 2017

Ello all, on a CAP Plus system, WQLV395 i.e., will a control channel (Ref the F.C.C. license information) ever have a LCN attached to it?? This system is listed as Conventional with the emission of 7K60FXD & 7K60FXE, nothing exotic.
I began to use my Analyze function, then started to wonder, if I include the listed control channels and mobiles, and they do not possess LCN's, well then it will never complete it's search assignment. I would assume that mobiles would not, but,,,,, a P25 system would not work in trunked mode if a person did not include a control freq. I know what happens when we ASSUME. So I'm sticking my neck out and asking first, in the Analyze function for CAP Plus, do I need to only use the FB station class code frequencies? Thank you for your help.

RayAir · Apr 10, 2017

AlphaFive said:
Ello all, on a CAP Plus system, WQLV395 i.e., will a control channel (Ref the F.C.C. license information) ever have a LCN attached to it?? This system is listed as Conventional with the emission of 7K60FXD & 7K60FXE, nothing exotic.
I began to use my Analyze function, then started to wonder, if I include the listed control channels and mobiles, and they do not possess LCN's, well then it will never complete it's search assignment. I would assume that mobiles would not, but,,,,, a P25 system would not work in trunked mode if a person did not include a control freq. I know what happens when we ASSUME. So I'm sticking my neck out and asking first, in the Analyze function for CAP Plus, do I need to only use the FB station class code frequencies? Thank you for your help.

Capacity Plus does not have a dedicated control channel. It has a rest channel. When you're sitting on the rest channel you'll notice a short data burst being sent every couple seconds.

Once two calls are in progress the rest channel will cycle to the next frequency and so on.

I do not have a DMR scanner. I use DSD+ to map Capacity Plus systems. It will display the LCN as well as tell you" This is the second repeater" or "This is the first repeater". It will also indicate what site # it is if it's a linked system.

Once you map the system to where the rest channel cycles through back to LCN 1/2, you have completed mapping the system.

DSD+ is a great tool for analyzing. It probably will provide more data than any analyze function on a scanner. If you have a disc tap on your scanner give it a try.

AlphaFive · Apr 10, 2017

Cap Plus

Hmm, man, now I'm really starting to wonder if my conventional hit on the freq that keeps giving me 'CAP' is from some other system............ The license for PSCG, WQLV395 lists control channels, even thought it is MOTOTRBO. I am going to have to spend more time researching this. So, I want to make sure I'm understandin' this. If a system is CAP PLUS.. the license should not have an FX station class code attached to it's frequencies? That's what I'm getting out of this. Thank you for your help, it is appreciated

werinshades · Apr 10, 2017

On a CAP+ System I monitor regularly, they use 2 alternating frequencies as rest channels, and can confirm neither one of them is used for voice. I have deleted them from the site frequencies list and have not had an issue. I know this is not the case on all CAP+ systems, but it's just a demonstration that some good investigative work never hurts.

AlphaFive · Apr 10, 2017

Cap Plus

Thank you for your help, it is appreciated..Okay, command decision here. I am going to use the Analyze function on one freq at a time, get a finish on the function, read the result, enter on my regular system list. I am fortunate that I'm only close enough to one site, and that one site only has a few frequencies. All I ever get is one hit anyway when I put them all in. This shouldn't take long. Thank you all. I'm really just trying to figure out, based on the station class code FB vs FX, if I can leave FX out. Take care

werinshades · Apr 10, 2017

AlphaFive said:
Thank you for your help, it is appreciated..Okay, command decision here. I am going to use the Analyze function on one freq at a time, get a finish on the function, read the result, enter on my regular system list. I am fortunate that I'm only close enough to one site, and that one site only has a few frequencies. All I ever get is one hit anyway when I put them all in. This shouldn't take long. Thank you all. I'm really just trying to figure out, based on the station class code FB vs FX, if I can leave FX out. Take care

I don't think the LCN Analyze feature will work unless you have it set up as MotoTRBO , not Conventional.

AlphaFive · Apr 10, 2017

Cap Plus

Yeah, that's right, I do have my system built as Cap Plus for the Analyzer. It's all good. I just ran the first freq from my local site, it hit it, finshed the function, sent it to my system. So that one is in, now through Sentinel, I added my second site freq into the system, then into Analyze, working on that one. I'll just go through the small list on the license and see what happens. This is what makes the 536 so cool. You are NEVER bored, haa. Thanks again

JASII · Apr 15, 2017

BCD536HP: Control Frequency On CAP Plus

I am working on a couple of systems locally that are "private carrier radios". I have been told by someone in a position to know that each of the two systems has four RF frequencies. When listening to them conventionally, it seems as if only three of the RF frequencies is active with traffic and a forth one doesn't seem to carry voice traffic.

However, it also seems like the fourth frequency, that doesn't typically carry voice traffic, might change from time to time. Has anybody here ran across this "pattern" yet?

jonwienke · Apr 16, 2017

That is typical. The control channel is not fixed, it rotates through available frequencies.

DaveNF2G · Apr 16, 2017

I don't believe the FCC data indicates "control channels." Which repeaters are assigned what functions within the system controller is beyond the scope of licensing.

garys · Apr 16, 2017

I agree. I've never seen a trunk system with a control channel listed in the FCC database. Maybe he means "control point", which is the physical location from which the system in run.

As others have said, Cap+ systems don't use a control channel per se. They use a rest channel that will move as it's frequency is used for voice traffic.

While the "rest channel" isn't used for voice, the frequency can be used for voice. In fact, it appears that when a radio indicates to the controller that it wants to use the system, the rest channel moves to the other slot. If both slots are filled, then the rest channel moves to the next repeater in the system. If both of those are used, then the rest channel moves on again, maybe back to the first frequency.

I wouldn't lock out the rest channels because then you're just listening at random.

DaveNF2G said:
I don't believe the FCC data indicates "control channels." Which repeaters are assigned what functions within the system controller is beyond the scope of licensing.

N1GTL · Apr 17, 2017

A basic rundown for Cap+ with two repeaters:

Freq A, slot 1
Freq A, slot 2
Freq B, slot 1
Freq B, slot 2

Assume 8 talk groups, 101 - 108. The system is turned on, day one and all radios are turned on.

The rest channel is Freq A, slot 1. ALL radios, ALL talk groups are monitoring this. TGID 104 keys up. All radios on TG 104 will open and receive the transmission. The rest channel moves to Freq A, slot 2. All radios NOT on TG 104 will being monitoring that Freq and time slot. TG 102 keys up. ALL radios on TG 102 will open and receive the transmission. The rest channel will drop to Freq B, slot 1 and ALL radios on other TG's will begin monitoring that, waiting for traffic on their talk group. This just continues on with the rest channel rotating between the 4 available time slots.

This over simplifies it but is basically how it works. There is no single control channel. The repeaters can be programmed to use a preferred repeater as the rest repeater. After x minutes of inactivity, the rest channel can move from wherever it is, to a specific repeater. I have not seen any set, most systems just leave it rotate.

Change this to 4 repeaters and 8 time slots with 15-20 talk groups and you can see why it is important to program things in the correct order.

AlphaFive · Apr 17, 2017

Cap Plus

Excellent information, all. And explained in a way that even I can understand it. Thanks for clearing things up. And,,, as soon as you said it, referring the F.C.C. license and control channels, I realized that's certainly true.

jeremym70 · Apr 23, 2017

So apparently in this area we now have two Cap+ systems, one is a single site and the other is a two site. But I would need to run either DMR Decode or DSD Plus to figure out the LCN's to program them into my 325P2 or 996P2?
I assume a single frequency is a single LCN, not two LCN's for the two time slots?
Thanks!

N1GTL said:
A basic rundown for Cap+ with two repeaters:

Freq A, slot 1
Freq A, slot 2
Freq B, slot 1
Freq B, slot 2

Assume 8 talk groups, 101 - 108. The system is turned on, day one and all radios are turned on.

The rest channel is Freq A, slot 1. ALL radios, ALL talk groups are monitoring this. TGID 104 keys up. All radios on TG 104 will open and receive the transmission. The rest channel moves to Freq A, slot 2. All radios NOT on TG 104 will being monitoring that Freq and time slot. TG 102 keys up. ALL radios on TG 102 will open and receive the transmission. The rest channel will drop to Freq B, slot 1 and ALL radios on other TG's will begin monitoring that, waiting for traffic on their talk group. This just continues on with the rest channel rotating between the 4 available time slots.

This over simplifies it but is basically how it works. There is no single control channel. The repeaters can be programmed to use a preferred repeater as the rest repeater. After x minutes of inactivity, the rest channel can move from wherever it is, to a specific repeater. I have not seen any set, most systems just leave it rotate.

Change this to 4 repeaters and 8 time slots with 15-20 talk groups and you can see why it is important to program things in the correct order.

DaveNF2G · Apr 24, 2017

In DSDPlus, there is a separate LCN for each frequency/slot combination.

Control freq. on CAP Plus

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