Control Channel Activity on 867.0750(San Berdo)

[rananthony04]

I was randomly scanning through the 800Mhz band and came across a control channel (867.0750). I searched the db and came across the channel in system 4's db(Morongo), however, it is not listed as a control or alternate control channel. I failed to log the system ID, but I did capture 2 TG's, Twentynine Palms Dispatch and Morongo Basin Ambulance Dispatch. Maybe someone else can confirm this before submitting it for the db? BTW, I was near the Phelan Sheriff's Sub Station when I came across the CC.

 

[zz0468]

In a Motorola Type II trunking system, the first 4 channels rotate through as control channels. They automatically switch every 24 hours. There really is no "primary" or "secondary" control channel.

 

[W6KRU]

In a Motorola Type II trunking system, the first 4 channels rotate through as control channels. They automatically switch every 24 hours. There really is no "primary" or "secondary" control channel.

You seem very knowledgeable on these things but I don't think that is correct. I believe that the San Diego Co RCS North simulcast cell almost always uses the same frequency(863.150) for the CC. I've never seen another frequency used for the CC.

 

[K6CDO]

You seem very knowledgeable on these things but I don't think that is correct. I believe that the San Diego Co RCS North simulcast cell almost always uses the same frequency(863.150) for the CC. I've never seen another frequency used for the CC.

zz0468 is correct. In SmartZone systems the first 4 channels are designated as Control Channels, and in many systems they rotate every 24 hours. The RCS does not rotate CCs as a matter of routine; however the loss of a transmitter on the primary CC will cause the cell controller to move the CC to the next available channel.

 

[W6KRU]

Thanks for the clarification Don. I was pretty sure that RCS didn't rotate every 24 hours.

 

[zz0468]

Just for clarity, the San Bernardino County systems are Smartnet, not Smartzone, and they rotate through the 4 control channels. The old System 4 does not, because that's an AMSS system that operates differently.

BTW, if you don't hear the CC on 4 different frequencies over the course of a few days, then one or more of the channels in rotation could be out of service temporarily for various reasons. And, as K6CDO pointed out, not all systems are configured to rotate CC's.

EDACS systems, like Riverside County uses, can use any channel as the control channel.

 

[f40ph]

Actually, I've been watching control channels lately. It appears ever since the reband capable radios have been starting to distribute, the systems only rotate between two control channels. My understanding is that the new radios are programmed with two old and two new channels. The system will use two old channels until all reband radios are out there. At that point, it will be told to start using the two new ones that should already be in everyone's radios. I'm not 100% sure at that point if they will continue to use the two older ones in addition to the new ones or just use the two new ones. It's possible that on some of the systems in SBCo the two older channels (850.000 series) are within the new reband spectrum. If you search the web, there's at least three scenarios that can be employed when making the final 800mhz rebanding changeover.

 

[f40ph]

I was randomly scanning through the 800Mhz band and came across a control channel (867.0750). I searched the db and came across the channel in system 4's db(Morongo), however, it is not listed as a control or alternate control channel. I failed to log the system ID, but I did capture 2 TG's, Twentynine Palms Dispatch and Morongo Basin Ambulance Dispatch. Maybe someone else can confirm this before submitting it for the db? BTW, I was near the Phelan Sheriff's Sub Station when I came across the CC.

In Victorville, you probably heard that 4-system control channel (and TGs) from the simulcast site on Rodman Mtn.

 

[zz0468]

Actually, I've been watching control channels lately. It appears ever since the reband capable radios have been starting to distribute, the systems only rotate between two control channels.

There are specific reasons for this on specific systems. It's related to ongoing programming efforts in certain mobiles.

My understanding is that the new radios are programmed with two old and two new channels.

Non-rebandable radios hold 4 control channels. Rebandable radios are capable of having 4 old, and 4 new control channels. When a system gets rebanded, so far as the mobiles are concerned, it's essentially a matter of turning off the old control channel frequencies, and turning on the new. The radio itself searches through all 8 when looking for a control channel to settle on.

The system will use two old channels until all reband radios are out there. At that point, it will be told to start using the two new ones that should already be in everyone's radios.

This is not quite correct. If there is a system that is currently using less than 4 control channels, it is because of specific temporary programming issues in a small number of mobiles.

I'm not 100% sure at that point if they will continue to use the two older ones in addition to the new ones or just use the two new ones.

Whatever the final configuration of specific frequencies San Bernardino county winds up with, ALL the Type II trunked systems will utilize 4 rotating control channels.

 

[f40ph]

Very good info: (just taking educated guesses in lieu of good info like yours).

Thanks!

 

[rananthony04]

Thanks you guys. This helps me gain a better grasp on SB's 800Mhz system(s).

 

[monitor142]

To zz0468,
I know San Berdo did a SED to replace the STX portables with XTS5000's; are they doing a SED to replace all the Spectras now? (For those that have no clue what I'm talking about, it pertains to rebanding).

Thanks.
-M142

 

[zz0468]

They're going to have to. Spectras are not rebandable. It's more complicated than it would be with portables. Every vehicle with a Spectra would have to go in and get the radio and control head changed.

 

[monitor142]

Thanks for the info. Assuming that they are going the XTL or APX mobile route that would mean a new cable from the trunk to the console too. Either way it's a PITA coordinating that many installs.
-M142