CHP Tan and Brown

[Elpablo]

Hi all,
Can someone please explain to me how the CHP uses these frequencies as I hear Oceanside (92) and Temecula (115) units on both it seems. I recently installed a Low Band antenna at my house with pretty good reception on both from Clairemont (SD).
It seems like they simulcast these frequencies maybe to use only one dispatcher? I have been listening for a while and would like to know if I just need to monitor one of these of if they ever have different traffic on them.
Thanks in advance!

 

[inigo88]

It seems like they simulcast these frequencies maybe to use only one dispatcher?

In my experience they are usually patched, probably for dispatcher staffing like you said. But it’s always possible they could un-patch the frequencies and work them separately in which case you would be missing half the traffic.

 

[P25Radio]

Could be patched, a CHP buddy of mine states Just the Tan Freq as far as he knows.

 

[Scanguysd]

for years the Temecula and Oceanside areas were covered with just the Tan Freq. however there was issues with tuning the Tan for both areas. So they split Temecula off and kept them patched. Every once in a while they will split or they have to redo the patch.

 

[Elpablo]

Thanks to all for their input. Good to know I am not missing anything.

 

[d119]

When CHPERS came around and the original MICOR-based simulcast was replaced with the multi-vendor mess they have now, the state was unable to synchronize the simulcast on the Tan with Santiago Peak in the mix. To fix the problem, they added lower-level sites to the Tan, and broke Santiago & company off onto a new channel called the Brown.

Tan and Brown are on a permanent patch and are staffed by a single dispatcher. It's only two channels because of the ineptitude and poor planning of our taxpayer funded "radio engineers" up in Sacramento. The current CHP radio system on lowband is the result of engineering personnel (who are STATE EMPLOYEES) who know nothing about the users, the system environment, and the fact that "cookie cutter" doesn't work when you don't have manufacturer engineers involved.

Play stupid games, win stupid prizes (like two channels!). I had lots of phone calls with state personnel when the system was initially replaced, trying to better explain the problems their units were having in language they can understand.

Anyone else love the new extender configuration, where transmissions are 10-1 because between two and four extenders come up on a scene at the same time? And they blame the radio system for that.

 

[inigo88]

Anyone else love the new extender configuration, where transmissions are 10-1 because between two and four extenders come up on a scene at the same time? And they blame the radio system for that.

I remember the old VHF extenders had a cool low tech solution, where every new unit that arrived on scene and turned the extender on would play a tone on startup which would tell the existing on scene extenders to power down.

I was wondering how they solved that with the new VRS digital extenders. Is the answer they didn’t?

 

[d119]

I remember the old VHF extenders had a cool low tech solution, where every new unit that arrived on scene and turned the extender on would play a tone on startup which would tell the existing on scene extenders to power down.

I was wondering how they solved that with the new VRS digital extenders. Is the answer they didn’t?

There is no priority resolution system with the new extenders. MY UNDERSTANDING is that each vehicle is supposed to set its "extender channel" on the CPVE to a specific channel for each car and set their handhelds accordingly, so each car is on a different frequency.

Once again, your tax dollars at work. There's gotta be something in the water up there in Sacramento, and I ain't kiddin...

 

[Scanguysd]

Close....

The way the CPVE works is when the repeater is activated for one patrol car it seeks to see if there is a master repeater active. If the system doesn't find one it becomes a master. If a master repeater is active in remains in a slave status until the master is turned off or the user can lock it as the master.

The "extender channel" or VRS channel is assigned to each low band channel. So, each car doesn't have a different frequency. With the VRS it solved the problem of units on bordering areas transmitting with the extender on two or more low band channels.

 

[gmclam]

Once again, your tax dollars at work. There's gotta be something in the water up there in Sacramento, and I ain't kiddin...

Water? What's that? We're in a drought.

 

[d119]

Close....

The way the CPVE works is when the repeater is activated for one patrol car it seeks to see if there is a master repeater active. If the system doesn't find one it becomes a master. If a master repeater is active in remains in a slave status until the master is turned off or the user can lock it as the master.

The "extender channel" or VRS channel is assigned to each low band channel. So, each car doesn't have a different frequency. With the VRS it solved the problem of units on bordering areas transmitting with the extender on two or more low band channels.

Based on my discussion with the manufacturer, there's no priority resolution scheme for the P25 VRS.

Whatever it is, it doesn't work.

 

[jodystott]

Based on my discussion with the manufacturer, there's no priority resolution scheme for the P25 VRS.

Whatever it is, it doesn't work.

Well I can confirm this (as a user). This is the way it works or suppose to work. Generally, it doesn’t work when two scenes are close together or several units at a scene. Also, the new EV20 (new radio, control head) will operate the same way. And their is new VRS frequencies coming.

 

[d119]

I know the new extenders are supposedly Pyramid SVR-P250 derivatives specific to the state. If I know Pyramid, those will be a quality product (seriously).

 

[Anderegg]

When CHPERS came around and the original MICOR-based simulcast was replaced with the multi-vendor mess they have now, the state was unable to synchronize the simulcast on the Tan with Santiago Peak in the mix. To fix the problem, they added lower-level sites to the Tan, and broke Santiago & company off onto a new channel called the Brown.

Tan and Brown are on a permanent patch and are staffed by a single dispatcher. It's only two channels because of the ineptitude and poor planning of our taxpayer funded "radio engineers" up in Sacramento. The current CHP radio system on lowband is the result of engineering personnel (who are STATE EMPLOYEES) who know nothing about the users, the system environment, and the fact that "cookie cutter" doesn't work when you don't have manufacturer engineers involved.

To expand on this, Brown is typically easier to receive at higher signal strength the more south and east you go in the county. Tan works better coming up the I-5 from Metro, and Brown works better coming up the I-15 from metro. It seems like both Tan and Brown can be transmit site selected by the dispatcher (?), because I can be sitting stationary and one will all of a sudden be much clearer than the other then the reverse later, or even on the next transmission. I know Orange is site selectable because I can be looking at the blinking red lights on Miguel and have Orange all of a sudden go weak signal on me. Because the Oceanside units need channel 2 car-to-car, their radios will always be on the Tan regardless of how horrible their reception is. When they do unpatch Tan from Brown (very infrequently), it is usually when one area is working something really major that is typing up the channel for hours and they move non-incident units to the other channel for normal calls.

On some nights, I can receive Baldwin Park CHP on the Orange better than the Tan at my station in Mt Hope with a CDM1550 with dedicated low band vehicle roof antenna. #sad

Paul

 

[inigo88]

Paul you are describing receiver voting. While the sites can be manually user selectable, CHP dispatch consoles can listen on the input frequency from every remote base station covering a given dispatch area and then automatically vote scan which site received the strongest signal on the input, and then that remote base site is automatically selected when the dispatcher keys up the PTT to reply. This allows the dispatcher to automatically reply from the closest mountain top to the last unit that transmitted. After the reply the system goes back to listening on all the inputs and waits to vote scan the next transmission starting the process over.

 

[Anderegg]

My stations old VHF GE system (161.700) operated similarly. The "voting" system was some giant thing the size of a refrigerator in a closet off of the newsroom. I think it was Chernobyl/School green with a giant GE emblem on it if memory serves. :-D

Paul

 

[celbaseman]

I recall, when CHP San Diego first went to 39 MHz with the repeaters, the first in the state I believe, they also or shortly afterwards tried to simulcast all of the transmitters. This seemed to work okay, until you got into an area or just outside of the service area, where the simulcasted signals would be so badly out of sync, the incoming signal would be distorted.

 

[d119]

Paul you are describing receiver voting. While the sites can be manually user selectable, CHP dispatch consoles can listen on the input frequency from every remote base station covering a given dispatch area and then automatically vote scan which site received the strongest signal on the input, and then that remote base site is automatically selected when the dispatcher keys up the PTT to reply. This allows the dispatcher to automatically reply from the closest mountain top to the last unit that transmitted. After the reply the system goes back to listening on all the inputs and waits to vote scan the next transmission starting the process over.

To a degree, that doesn't make sense. Why simulcast then? And it would be transmitter steering if it affects base to mobile transmissions, receiver voting is the other way around.

 

[d119]

I recall, when CHP San Diego first went to 39 MHz with the repeaters, the first in the state I believe, they also or shortly afterwards tried to simulcast all of the transmitters. This seemed to work okay, until you got into an area or just outside of the service area, where the simulcasted signals would be so badly out of sync, the incoming signal would be distorted.

It's still simulcast. Tait Quasi-Sync with FEI-Zyfer frequency standards.

 

[inigo88]

To a degree, that doesn't make sense. Why simulcast then? And it would be transmitter steering if it affects base to mobile transmissions, receiver voting is the other way around.

Sorry, “receiver voting” on the remote base input, aka transmitter steering.

And I completely agree, if it’s a simulcast area this would be N/A, but I believe many CHP channels aren’t simulcast especially in larger coverage areas. I’ve also heard anecdotally that the mobile units being rebroadcast on the base frequency is an optional feature that some dispatchers would unselect and others would leave on (hence all the “what happened to the mobile units?” RR forum posts over the years), because the “repeater” is really just a console patch from the mobile frequency to the base frequency.

Finally in the non-simulcast areas things can get confusing when that mobile rebroadcast is switched on, because they generally only pick one mountaintop to do it from, where as the dispatcher will transmitter vote/steer to the strongest mountain top for the last unit. To the scanner listener this can manifest as really scratchy mobile units and then crystal clear dispatcher sometimes and scratchy dispatcher other times.

As to Paul’s example, if it was in a simulcast area (which rereading he said the Orange so it would have been) it doesn’t make sense unless they turned the simulcast off and reverted to transmitter steering for some reason.