Why list control channels on a P25 Standard?

[cws]

I've just recently set up my first Project 25 Standard system (Fort Hood), and being ignorant of some things, despite my readings here, I input only the red and blue control channels. So, of course, I was missing a lot of traffic on the four sites. Someone posted that there was a new control channel being used on the Main Post site, and it was one I had not entered. So, now I've figured out that I have to enter all of the frequencies in the database for that type of system. (I'm learning!)

My question is this: Of what value is having the control channels listed in the database for a Project25 Standard system, since I need to put them all in, anyway? I'm sure there must be some value, for someone, right?

Thanks in advance for the education.

 

[rdale]

You only need the control channels for 800MHz systems.

 

[cws]

You only need the control channels for 800MHz systems.

Because they are Mot Type II systems, right? But, my question remains.

 

[rdale]

No, they are P25 systems. Mot Type II is not P25 Standard.

You don't need anything more than the control channels. I'm assuming you are inputting a 400MHz system, which doesn't have the same standard bandplan.

 

[MNRotrMedic]

Actually for the P25 systems you should ONLY need the control channel. It sounds as though you were missing one of the control channels and that was what caused you to miss transmissions. You wouldn't be wrong to program all of the system frequencies but it is unnecessary.

If the system is 400MHz you will definitely need the bandplan to be sure to track the system properly.

If i remember correctly, if the band plan is wrong on a UHF (or VHF) system even having all of the system frequencies programmed will not let the scanner track the system with any accuracy.

M

 

[cws]

Now, I am confused. This system
http://www.radioreference.com/apps/db/?sid=5738
uses freqs around 380-381 Mhz. After entering all freqs, including the CC (380.7625) I had left out, which was pointed out as an unmarked CC by someone, I don't get all that much more traffic, so I'm thinking entering only CCs was enough. HOWEVER, I think there's more traffic than I'm getting, so maybe y'all are onto something; the bandplan, which the scanner set up for me, I presume, lists only Base 380.00000, and 12.500 Khz spacing. Is that correct, and complete enough?

Thanks for your help, guys!

EDIT: Also, how did that person know that freq was a CC? The freq displayed is just the voice channel being used isn't it?
Nevermind. I see it displays the CCs as it is searching.

EDIT again: Now, I found this on the Wiki under 'control channel only':
"Older Uniden radios require that a plan be programmed, as well as all the control channels, for CCO to work. RS/GRE radios including the New GRE radios, as well as the newer DMA based Uniden scanners, do not require a plan. In addition, no plan is required when utilizing CCO in the 900 Mhz band."

If that is absolutely accurate, then I guess I must have my 396T set up perfectly alright. But, then on a Project 25 Standard system, the setup does not give you the option of CCO. That's only available on a MOT system. What a mess!

 

[UPMan]

Some P25 systems (mostly military) do not include the band plan information on the control channel. For those systems, you must manually program the band plan. I don't know if that is the case with the Ft. Hood system, though. (Usually, if the band plan is needed it is in the RRDB unless the system is very new.)

 

[cws]

Some P25 systems (mostly military) do not include the band plan information on the control channel. For those systems, you must manually program the band plan. I don't know if that is the case with the Ft. Hood system, though. (Usually, if the band plan is needed it is in the RRDB unless the system is very new.)

I'm quickly learning there are not many FIRM RULES to any of this radio scanning stuff. Everything has exceptions.

No mention of a "plan" on RRDB for the Ft. Hood system, and I am getting traffic on at least several frequencies, so I reckon it's setup OK.

Thanks for everyone's input.

 

[WayneH]

Moved to GenScan.

 

[KB8UYC]

I've just recently set up my first Project 25 Standard system (Fort Hood), and being ignorant of some things, despite my readings here, I input only the red and blue control channels. So, of course, I was missing a lot of traffic on the four sites. Someone posted that there was a new control channel being used on the Main Post site, and it was one I had not entered. So, now I've figured out that I have to enter all of the frequencies in the database for that type of system. (I'm learning!)

My question is this: Of what value is having the control channels listed in the database for a Project25 Standard system, since I need to put them all in, anyway? I'm sure there must be some value, for someone, right?

Thanks in advance for the education.

CWS,

Let me see if I can further answer your question since nobody else is. All they are doing is confusing you. If your monitoring a P-25 digital system, there are control channels, a primary and a secondary for each of the tower sites. In a Simulcast system(multiple towers, but all towers use the same control frequency) and in a state wide simulcast system like the MPSCS(Michigan Public Safety Communications System) each tower has a different control channel.

Most P-25 systems operate the same way. So, when programming your scanner, you only need to input the Primary control channel and the Secondary control channel. *IF* for some reason the control channel has changed because the techs are working on it or something, usually that info will get here. I know your just starting out, but if your monitoring a P-25 system, then I highly suggest that you download PRO96COM. If you have a Radio Shack and or a GRE scanner operation is flawless. If you own a Unident scanner then I suggest contacting Mickey60 here on the boards and he can help you with that. Basically that program will tell you what frequencies are used on a particular tower that you are monitoring. If the control channel changes for whatever reason, then it will show that.

You do not need to input all the channels of the system that you are monitoring. Chances of any of the voice channels being used as control channels is slim. If the control channel actually changes, then they are probably using a new frequency. This is why it is very important to pay attention to the system that you are monitoring. Know its in's and out's. Learn all you can about the system so that when something does change, you know that it has changed and what you need to do.

I hope this has helped you out. Are you still confused?

 

[Alarms50]

I am surprised no one has picked up on this point yet. From what I understand Control Channel operation is ONLY available for 800MHz systems. The Fort Hood system he linked to is UHF. All non-800MHz systems (including VHF and UHF) NEED to have ALL frequencies programmed. On these non-800MHz systems you also need to program the correct Base/Step/Offset settings.

 

[rdale]

I am surprised no one has picked up on this point yet. From what I understand Control Channel operation is ONLY available for 800MHz systems.

Only for older scanners...

http://wiki.radioreference.com/index.php/Control_Channel_Only

"it is available on all bands where trunking is supported in the Uniden scanners that support DMA." (He has a 396T which supports DMA)

 

[nd5y]

The OP might have one or more of several problems here
1. Trunked systems have several voice channels and can have several talkgroups active at the same time. Your scanner can only receive one talkgroup at a time and it will miss everything else that is going on at that time.

2. The Fort Hood system is a multi site non-simulcast system.
Somebody correct me if this is wrong but as far as I know,
in order to hear all the traffic you would have to be able to hear all the sites at the same time because the radios can be on a different site for each transmission.
You would have to program each site as a separate system and while you are scanning one site you will miss transmissions on the others. It takes several seconds for the scannner to go through each system so you will miss short transmissions.

So, you would need one scanner for each talkgroup on each site that you want to monitor, and be in receiving range of each site, to be able to hear all the traffic all the time.

 

[N8IAA]

Now, I am confused. This system
http://www.radioreference.com/apps/db/?sid=5738
uses freqs around 380-381 Mhz. After entering all freqs, including the CC (380.7625) I had left out, which was pointed out as an unmarked CC by someone, I don't get all that much more traffic, so I'm thinking entering only CCs was enough. HOWEVER, I think there's more traffic than I'm getting, so maybe y'all are onto something; the bandplan, which the scanner set up for me, I presume, lists only Base 380.00000, and 12.500 Khz spacing. Is that correct, and complete enough?

Thanks for your help, guys!

EDIT: Also, how did that person know that freq was a CC? The freq displayed is just the voice channel being used isn't it?
Nevermind. I see it displays the CCs as it is searching.

EDIT again: Now, I found this on the Wiki under 'control channel only':
"Older Uniden radios require that a plan be programmed, as well as all the control channels, for CCO to work. RS/GRE radios including the New GRE radios, as well as the newer DMA based Uniden scanners, do not require a plan. In addition, no plan is required when utilizing CCO in the 900 Mhz band."

If that is absolutely accurate, then I guess I must have my 396T set up perfectly alright. But, then on a Project 25 Standard system, the setup does not give you the option of CCO. That's only available on a MOT system. What a mess!

If you carefully looked at the frequecies, you will have noticed that they were highlighted in yellow. This indicates that there was a change. I use CC only for my local P-25 systems. One of the systems changed CC's. I had it programmed in because being familiar with the older frequencies, and knowing that they were in the process of rebanding, put all the old CC's in minus the 15Mhz. Never missed any comms. But, there were those that did. Checked it with Pro96com, and it confirmed that they had finished rebanding. All of the older frequencies were no longer active. With a new CC that needed to be put in by others. Again, I am using a Pro-96 and Pro-106. Don't know how the 396 sets up for P-25 at all.
HTH,
Larry

 

[BaLa]

Old Post...

was going through some stuff, so I found it.

You do ONLY need to CC on this system to track it properly. (on the 396t)
The thing is, if you put the Current CC in as the only chan, and they rotate CCs tommorow, it will be
'dead' to your scanner.
so you might as well put them all in.

With it being Multi-Site you could miss some stuff that way.
Also, some of the TGs are encrypted so thats another reason he might be missing stuff.


Haven't messed with this system much recently. but some Trunking Systems switch CCs quite often.

 

[W6KRU]

Haven't messed with this system much recently. but some Trunking Systems switch CCs quite often.

That doesn't sound right. Wouldn't that require re-programming all of the radios in the system? Are you talking about switching to an alternate CC or converting a voice channel to a CC.

 

[davidbond21]

That doesn't sound right. Wouldn't that require re-programming all of the radios in the system? Are you talking about switching to an alternate CC or converting a voice channel to a CC.

No, when you turn a radio on(or scanner), it scans through its list of programmed frequencies until it finds one of those channels transmitting CC data and then works from there. There's no difference between a repeater carrying the CC and another carrying voice. It's just whatever it has been assigned to do.

 

[W6KRU]

No, when you turn a radio on(or scanner), it scans through its list of programmed frequencies until it finds one of those channels transmitting CC data and then works from there. There's no difference between a repeater carrying the CC and another carrying voice. It's just whatever it has been assigned to do.

I'm not sure we're talking about the same thing. Bare with me if I'm being dense again. If all of the mobiles are listening for a CC on x,y, or z freqs. and then you want them to listen to w, x, or y for a CC, wouldn't that require re-programming the mobiles?

Or are you saying that the mobiles listen to all frequencies, including voice channels for a CC?

 

[davidbond21]

Well, I guess I'm speaking from an EDACS standpoint, and don't know if this holds exactly true for P25.

If you have frequencies w, x, y, z, you don't have to tell the radio which of those is the control channel, it will scan through all of them until it finds it. If you have frequencies a-z, it will scan through all until it detects the CC, but you don't have to tell it which of those to look for the control channel on, the radio recognizes the signal and gets to work. If it happens to lose signal or the control channel changes to a new frequency, it will go into scan mode again until it finds the new CC.

All the channels or frequencies can carry voice, and they can all carry data. The radio doesn't make any distinction during programming what a frequency pair is used for, it just has to be entered in(and in the case of EDACS, in logical order).

 

[W6KRU]

Well, I guess I'm speaking from an EDACS standpoint, and don't know if this holds exactly true for P25.

If you have frequencies w, x, y, z, you don't have to tell the radio which of those is the control channel, it will scan through all of them until it finds it. If you have frequencies a-z, it will scan through all until it detects the CC, but you don't have to tell it which of those to look for the control channel on, the radio recognizes the signal and gets to work. If it happens to lose signal or the control channel changes to a new frequency, it will go into scan mode again until it finds the new CC.

All the channels or frequencies can carry voice, and they can all carry data. The radio doesn't make any distinction during programming what a frequency pair is used for, it just has to be entered in(and in the case of EDACS, in logical order).

I didn't think we were talking about the same thing. The way I understand it, on P25 the CC tells the radios where the voice channel is supposed to be and the radio switches to the appropriate frequency. The mobiles, or your scanner, don't have to know what the voice channels are before hand. I only put the CCs in my scanner.