CHP 700 MHz Extenders

[zerg901]

Just to state the bloody obvious -

Seems to be 1 VRS channel associated with each "radio zone" - (I saw one mention of a split "radio zone" in this thread though)

VRS1 to VRS16 show up on the statewide list (some multi times)

If there is a statewide VRS channel - perhaps it would have to be VRS17 or above

 

[Radio_Lady]

If there is a statewide VRS channel - perhaps it would have to be VRS17 or above

I'm not clear on what the purpose of a statewide VRS channel would be. Unless they get a "universal" statewide channel pair like old Blue has been (just different PLs), it would almost have to be quickly user-configurable to any of the many dozens of frequency and tone combinations they're hesitatingly building out.

 

[zerg901]

I thought that CHP had a bunch of Tac channels, Division channels, and statewide channels. I didnt realize they were so thin on channels. For a big wildfire, manhunt, or earthquake, disaster, riot, etc, I was expecting that they had multiple channels to use 'on scene' - with a need to patch 700 Mhz HTs to low band channels.Looking at the CHP database, it seems that they are lucky if they can use 1 repeater pair at any 1 particular location.

Come to think of it - how many times are VRS15 and VRS16 in that table? Once or twice? (VRS15 - Casto 2nd + Hayward 2nd + Baldwin Pk 2nd) - (VRS16 - Solano 2nd + East LA 2nd) - (VRS 14 - Contra 2 + San Jose 2 + Central LA 2 + Ranco Cuco 2) - (VRS 13 - Academy 2 + Dublin 2 + Napa 2 + Altadena 2 + Santa Ana 2)

 

[Radio_Lady]

The do have a bunch of channels, with a real wealth more in the works with the addition of all the "new" 39, 44, and 45 mHz frequencies. The "catch 22" with VHF-low of course is the trade-off between solid propagation over their huge expanses of topographically complex real estate, and then the flip side of both intrastate and interstate skip interference. Missouri comes to mind. For planned events (Rose Parade, etc) and for unplanned disasters and unusual occurrences they can quickly set up temporary repeaters, drawing from that wealth of frequencies

I don't understand your "lucky if they can use 1 repeater pair at any 1 particular location" comment since there are a many multi-frequency sites in metropolitan areas all around the state. Except for some really remote areas, my guess without looking is that most sites have at least two pairs, and many have a lot more than that.

But that's getting us off-topic for this thread. My question is still what kind of use or coinfigurability you're envisioning for the "VRS17" channel you suggest.

 

[zerg901]

I dont really want to "suggest" anything - but

If 42.34 had repeaters statewide - then VRS17 and 42.34R could be a 2nd channel available at any scene to supplement the local channel office. (Similar to how many fire agencies in California now have a Dispatch repeater and a Command repeater coverage in many areas). Very simple to conceptualize and understand for the ground troops.

You said that many CHP sites have multi repeaters. Would this be 42.34 plus the local area office channel? Or is this a local office channel plus a adjacent office channel?

(If I did "suggest" something, I would first ask - Has CalFire narrowbanded yet? If and when CalFire does narrowband, who will be the winner of some new channel pairs? Not CHP apprently).

 

[Sac916]

I dont really want to "suggest" anything - but

If 42.34 had repeaters statewide - then VRS17 and 42.34R could be a 2nd channel available at any scene to supplement the local channel office. (Similar to how many fire agencies in California now have a Dispatch repeater and a Command repeater coverage in many areas). Very simple to conceptualize and understand for the ground troops.

You said that many CHP sites have multi repeaters. Would this be 42.34 plus the local area office channel? Or is this a local office channel plus a adjacent office channel?

(If I did "suggest" something, I would first ask - Has CalFire narrowbanded yet? If and when CalFire does narrowband, who will be the winner of some new channel pairs? Not CHP apprently).

The bottom line is that CHP doesn't have a need to have a sizable batch of Tactical channels. CHP's focus is on traffic safety and the protection of State assets ( Government buildings, sites and offices ) CHP does get involved in "riots" and "natural disasters" but the vast majority of time they take a secondary role for those type of incidents.

I'm not trying to "put down" the CHP in the slightest, but their role is unique. Rarely do they head a (large scale) manhunt that requires a tactical operation with CHP in charge. Yes they participate in some large scale events, but the primary department is most often the local Sheriff's Department (Police Department for Government buildings/sites)

Even at the State Capitol, during large scale demonstrations and protests, they do just fine. Supplemented by local law enforcement, the number of CHP channels is of little concern. One or two channels are just fine.

Here in Northern California, I can say CHP does quite well utilizing their existing tactical channels and 400Mhz freqs. Despite some significant radio interoperability issues with local departments, things end up working out well. Not perfect, but adequate.

CHP has a sufficient number of Tac channels to conduct investigations, stakeouts and various enforcement duties. If the event becomes a large scale, CHP will quickly become dwarfed by local law enforcement. Obviously you'll have some rural areas where CHP may equal, but CHP rarely takes a lead role on such events.

CHP could use more primary channels in my opinion, they're radio traffic is non-stop at times for routine business. I can't monitor them, my brain begins to hurt after a few minutes.

PS
Here is a Jan 2012 doc http://www.chp.ca.gov/html/pdf/chpers_legislative_report_2012.pdf

 

[officer_415]

I thought that CHP had a bunch of Tac channels, Division channels, and statewide channels. I didnt realize they were so thin on channels. For a big wildfire, manhunt, or earthquake, disaster, riot, etc, I was expecting that they had multiple channels to use 'on scene' - with a need to patch 700 Mhz HTs to low band channels.Looking at the CHP database, it seems that they are lucky if they can use 1 repeater pair at any 1 particular location.

The whole point of the VRS is that it gives officers the ability to transmit on multiple bands. They have VHF low band, VHF high band, UHF, and 700/800 MHz radios in the trunk, and the VRS gives them the ability to go out on any channel programmed in those radios, directly from their portable. There is no point in a statewide VRS channel, because they already have access to dozens of channels using just one 700 MHz frequency pair.

If 42.34 had repeaters statewide - then VRS17 and 42.34R could be a 2nd channel available at any scene to supplement the local channel office. (Similar to how many fire agencies in California now have a Dispatch repeater and a Command repeater coverage in many areas). Very simple to conceptualize and understand for the ground troops.

They did have 42.34 BLUE repeaters statewide. They are phasing that system out in favor of a separate blue channel for each division. This will permit each division to utilize their blue channel for local incidents without interfering with the operations of neighboring divisions. So each area has two repeated channels (their primary dispatch channel and their division-wide blue channel), plus various non-repeated tacticals.

 

[zerg901]

mlangeveld, I think you have shown that they do need a statewide VRS channel. If there are local repeaters and division wide repeaters, plus tactical channels, then how will 700 Mhz portables access 3 or more low band networks with only the 2 presently assigned VRS channels for each radio zone? If CHP could find a way to clear VRS16 of its 2 assigned usages, then VRS 16 could be a statewide VRS channel.

If VRS16 was paired with 42.34R statewide - and if all of the 42.34 repeaters operated in synchronized simulcast mode, you could have a true "statewide channel" that would allow 1 portable radio to talk to another portable radio anywhere in the state. (This seems to be a frequently touted feature on statewide TRS in various states).

 

[officer_415]

mlangeveld, I think you have shown that they do need a statewide VRS channel. If there are local repeaters and division wide repeaters, plus tactical channels, then how will 700 Mhz portables access 3 or more low band networks with only the 2 presently assigned VRS channels for each radio zone? If CHP could find a way to clear VRS16 of its 2 assigned usages, then VRS 16 could be a statewide VRS channel.

If VRS16 was paired with 42.34R statewide - and if all of the 42.34 repeaters operated in synchronized simulcast mode, you could have a true "statewide channel" that would allow 1 portable radio to talk to another portable radio anywhere in the state. (This seems to be a frequently touted feature on statewide TRS in various states).

I don't think you understand how the VRS works. They have access to ALL of their low band channels using their primary VRS channel. The system uses one 700 MHz frequency pair to communicate between the car and the portable, and the officer can access every channel programmed in the car's radios using different NACs. The secondary VRS channel is simply a backup in case the primary fails.

As for a statewide 42.34 BLUE simulcast, that would not really be feasible. Low band is very difficult to simulcast due to its wide propogation area. That's why you don't see many low band simulcast systems.

 

[ScannerDude244]

Seems like a lot people are confused on how the 700mhz work with CHP they are just use a access point like a router/switch to a network that's it. Portable Radio to Car Radio

 

[Radio_Lady]

Zerg, it might help to visualize the VRS radio as a souped-up version of an under-dash radio control head with a speaker/mic, but just wireless.

You only need one control head (in this case, one VRS radio and channel) to essentially dial up and use any channel on any of the radios in your trunk, on whatever band.

In practice, your VRS radio will usually be tuned to your dispatch channel (through your car's low band radio).

I think this is the essence of the VRS concept, but very over-simplified. I'm sure others will correct my misunderstandings and add to this

 

[inigo88]

What he said. I think you're missing the point of VRS.

VRS stands for Vehicular Repeater System. It's exactly like the VHF mobile extender but they moved it up to 700 MHz instead. The CHP lowband system is not designed to support the use of portables, and it won't be in the foreseeable future. Instead, when the officer leaves the patrol car they switch on the VRS 700 MHz extender, which is simply a 700 MHz base station wired to the lowband mobile radio in the car. The officer can then talk on their portable, which is picked up by the 700 MHz VRS base station in the car, which then keys up the patrol car's lowband mobile radio to communicate with CHP dispatch. It's like a crossband repeater in the car, only it uses one frequency instead of two - just like the old extenders!

On the old VHF extenders, once you set the lowband channel in the vehicle, you couldn't change it when you were out on portable. The portables all used 154.905 MHz and one channel activated the Car-to-Station mode in the vehicle (using one PL tone), another channel activated Car-to-Car mode (using another tone), and a third was just portable to portable using CSQ.

In comparison, the new 700 MHz VRS extenders are pretty cool. Unlike CTCSS which is usually limited to 16 standard tones, the digital 700 MHz VRS have a huge variety of NAC codes to choose from. So using different combinations of NAC codes on the same VRS frequency, the officer can use the portable radio to tell the car which lowband channel to switch to.

Therefore, there is NO reason for a statewide VRS channel. Each division gets their own dedicated VRS channel based on geographic location (plus a secondary!). You can then access ANY lowband channel in the vehicle from the portable, using the same frequency, because each mobile channel is assigned a different NAC.

I hope this helps clear up any confusion on how the CHP VRS system works.

 

[K6CDO]

I dont really want to "suggest" anything - but

_..._

(If I did "suggest" something, I would first ask - Has CalFire narrowbanded yet? If and when CalFire does narrowband, who will be the winner of some new channel pairs? Not CHP apprently).

CalFire has narrowbanded. The winner of the new channels is CalFire.

CHP was given the chance to migrate to VHF-High by the VHF-High agencies (CalFIRE, CalEMA, DOJ, DFG, and DWR) who were looking to set up a statewide VHF trunked network in 2004-05. CHP's response was "No Way. We need to cover too much area for a VHF-High solution to work." Never mind that the CHP covers only the road network, and CalFire, DOJ and DFG routinely work off-road in an even larger foot print ...

 

[inigo88]

CalFire has narrowbanded. The winner of the new channels is CalFire.

CHP was given the chance to migrate to VHF-High by the VHF-High agencies (CalFIRE, CalEMA, DOJ, DFG, and DWR) who were looking to set up a statewide VHF trunked network in 2004-05. CHP's response was "No Way. We need to cover too much area for a VHF-High solution to work." Never mind that the CHP covers only the road network, and CalFire, DOJ and DFG routinely work off-road in an even larger foot print ...

If CHP had joined a VHF High statewide trunked solution, I wonder who would snatch up all the lowband channels?

 

[Radio_Lady]

What he said. I think you're missing the point of VRS.

The CHP lowband system is not designed to support the use of portables, and it won't be in the foreseeable future. Instead, when the officer leaves the patrol car they switch on the VRS 700 MHz extender, which is simply a 700 MHz base station wired to the lowband mobile radio in the car. The officer can then talk on their portable, which is picked up by the 700 MHz VRS base station in the car, which then keys up the patrol car's lowband mobile radio to communicate with CHP dispatch. - - using different combinations of NAC codes on the same VRS frequency, the officer can use the portable radio to tell the car which lowband channel to switch to.

I hope this helps clear up any confusion on how the CHP VRS system works.

I appreciate the clarifications, inigo88. My main misunderstanding was that I thought the VRS portables could access VHF-high and UHF radios in the car, but that isn't the case - low band only? Or are the VRS's themselves multiband for UHF, too? I think my multi-term memory is fading fast.

If memory serves, the immediate precipator for getting the original extenders was the late night murder of two CHP officers on the causeway west of Sacramento back around 1980 or so. Having no portables, they never had a chance to call for help, and I think they were found by passers-by. Low band portables' transmit distance is severely handicapped by the antenna issue of course. LA City Fire had the same problems when they were on 33 mhz. Rig radios worked fine, but not their portables, other than for very close unit-to-unit traffic.

 

[officer_415]

I appreciate the clarifications, inigo88. My main misunderstanding was that I thought the VRS portables could access VHF-high and UHF radios in the car, but that isn't the case - low band only? Or are the VRS's themselves multiband for UHF, too? I think my multi-term memory is fading fast.

The VRS portables can only operate on 700/800 MHz directly, but they can access the VHF high band and UHF radios in the car.

 

[inigo88]

Yep I'm sorry, I was only mentioning the general ability to control the car radios - but you were right it includes the VHF and UHF on addition to the existing lowband.

And since they operate on 700/800 MHz directly, they have access to all the CAL-IFOG/NIFOG national interop channels (7CALL/7TAC, 8CALL/8TAC and several CHP licensed 700 MHz digital conventional frequencies. The VRS frequency is strictly for controlling the car radios from the portable (via different NAC inputs).

It's pretty cool! Now if they could just find a way to make the digital VRS audio not sound so crappy on analog lowband...

 

[zerg901]

1. There was a previous thread that said CHP already uses synchronized simulcast on lowband IIRC.

1A . I have not understood how mobile repeaters (MO3) work since about 1976

2. If the VRS can be tied to various channels on the fly, then there might be more problems with this scheme than I thought initially. If you have an incident with 3 CHP officers at a scene with VRS, and 1 wants to talk thru his mobile on lowband, 1 wants to talk thru his mobile on highband, and 1 wants to talk thru his mobile on UHF, then what VRS channels will be used? There are only 2 VRS channels allocated per radio zone. I dont think anyone wants any 1 VRS channel to be carrying traffic from two different channels at VHF or UHF or wherever.

Maybe it would help to diagram this situation -

CHP Officer 1 on 700 Mhz portable on VRS 1 >>> mobile radio 1 >>> low band channel

CHP Officer 2 on a 700 Mhz portable on VRS Channel 2 >>>> mobile radio 2 >>> VHF channel

CHP Officer 3 on a 700 Mhz portable on VRS Channel ??? >>> mobile radio 3 >>>> UHF channel

Per the list of allocated VRS channels (posted earlier in this thread), any incident will be at most able to support 2 VRS at the same time.

 

[tahoekid77]

If memory serves, the immediate participator for getting the original extenders was the late night murder of two CHP officers on the causeway west of Sacramento back around 1980 or so. Having no portables, they never had a chance to call for help, and I think they were found by passers-by.

From the CHP website:

Woodland
December 22, 1978

Officers Roy P. Blecher and William M. Freeman were partners, working out of the Woodland Area Office, when they were gunned down along Interstate 80 near the Yolo Causeway in West Sacramento. Investigators found signs of a struggle. Blecher was handcuffed and shot in the back of the head and Freeman had been overpowered, shot and killed. Their last radio contact was at 3:12 a.m. when they stopped a suspect for a routine traffic violation. The killer was captured, tried and convicted of the murders and is currently serving a life sentence. Officer Blecher, 50, was a 21-year CHP veteran and Officer Freeman, 32, was a 12-year Patrol veteran.

 

[markclark]

I heard a pursuit in L.A. today and units were assigned both the Blue channel and given a VRS channel to operate on. The VRS assignment was given too quickly for me to take it down. The units were West Valley and Central L.A. CHP cars.