CHP & Trunking 2024

[mmckenna]

And I just bought three more. A 996 P2 and two BCT15Xs. I must admit I don't know how to program the San Bernardino fire department system because up until now I've been listening to their VHF patch channels. I had no clue CHP was about to vacate low band.

I wouldn't say they are going to vacate low band. It's still useful in many parts of the state, and all the new radios they've been installing have included low band capability.

I don't think low band is going anywhere anytime soon.

I imagine they will stay on low band up in the mountains and up in Mammoth and Truckee; Up in the Sierras and the Kings.

Probably. They appear to be multicasting some low band channels on CRIS, so a mix of both. The radios are smart enough to choose whatever they can hear.
Nice thing about the LTE integration on trunked radio systems is that it can be set to fall back on LTE if it can't find a control channel, so a good hands off solution that doesn't require user intervention.

I spent a lot of time up in Big Bear and I can tell you that the cellular system sucks, so LTE is not going to be much help to them.

LTE coverage is improving every day, as the wireline carriers want to get out of supporting copper cable, more and more users go to cellular and the network grows.
LTE is useless in some areas, but those are usually the areas where two way radio, especially VHF and VHF low work well.

But I do hear CHP units complain that they can't hear dispatch. Upon research it appears that there is so much computer generated noise in newer vehicles like the Ford Interceptor that it wipes out the VHF low-band receivers.

This is all new to me. I would think they'd have been able to make a filter by now.

Yeah, our new chief is an ex-CHP guy, and he is not a low band fan...

 

[HappilyRetired]

I wouldn't say they are going to vacate low band. It's still useful in many parts of the state, and all the new radios they've been installing have included low band capability.

I don't think low band is going anywhere anytime soon.



Probably. They appear to be multicasting some low band channels on CRIS, so a mix of both. The radios are smart enough to choose whatever they can hear.
Nice thing about the LTE integration on trunked radio systems is that it can be set to fall back on LTE if it can't find a control channel, so a good hands off solution that doesn't require user intervention.



LTE coverage is improving every day, as the wireline carriers want to get out of supporting copper cable, more and more users go to cellular and the network grows.
LTE is useless in some areas, but those are usually the areas where two way radio, especially VHF and VHF low work well.



Yeah, our new chief is an ex-CHP guy, and he is not a low band fan...

This last summer I got to sit in on a VHF amateur radio contest for my club and I got to talk on 6 m. It was intense. Apparently I was on a beam with 1500 watts pointed East and everybody could hear me. If low band can work that well it's a shame it's not more reliable for public safety.

I remember when I was in the military working intelligence. We had radios in our operation room and we could hear stateside stations coming into Germany quite well. As if they were right out in front. That was during Vietnam and it truly amazed me that the PRC units are soldiers had were very low power but had tremendous range.

To the topic, I can understand now why LTE has been built into the system. When I looked at CRIS I couldn't understand how so few repeater sites could handle all of the radio traffic from multiple agencies. CHP being the primary on the system and them being on the freeway most the time adjacent to cell towers, I can see LTE working for them. If anything for remote receive? I'm going to stay in bounds here, but the video I watched of the Deputy Commissioner, she sounded gleeful that they were going encrypted. Not much happens on CHP that requires encryption. But that's the way it goes. It is fortunate that the system I am building is more fire related. CHP was just a bonus.

 

[mmckenna]

This last summer I got to sit in on a VHF amateur radio contest for my club and I got to talk on 6 m. It was intense. Apparently I was on a beam with 1500 watts pointed East and everybody could hear me. If low band can work that well it's a shame it's not more reliable for public safety.

Depends too much on atmospheric conditions.
Also, CHP can't drive around with huge directional antennas on their cars hooked up to a 1,500watt amplifier. One, it's physically impossible. Two, FCC has limits on ERP, as these frequencies were at one time used by other states.

Kind of hard to do much with low band and a manageable size antenna. Also the same reason why CHP doesn't carry portable low band radios.

I remember when I was in the military working intelligence. We had radios in our operation room and we could hear stateside stations coming into Germany quite well. As if they were right out in front. That was during Vietnam and it truly amazed me that the PRC units are soldiers had were very low power but had tremendous range.

Yeah, HF is amazing. Add ALE, and you've got an almost fool proof communications system. Comes back to the antennas, though. Driving around with a 12 foot long whip on a car is a bit of a challenge. Makes them much easier to spot, though….

To the topic, I can understand now why LTE has been built into the system. When I looked at CRIS I couldn't understand how so few repeater sites could handle all of the radio traffic from multiple agencies.

That's the beauty of trunking. I've got 450 users on a 5 channel trunked system and it is extremely rare to have enough congestion to cause issues. Rare as in a few seconds a year.

Mr. Erlang did a nice job figuring it out for telephone networks. Since trunking system are just RF based phone systems, it's pretty easy to figure out how many trunks you need on the system to handle calls:

Erlang (unit) - Wikipedia

en.wikipedia.org

CHP being the primary on the system and them being on the freeway most the time adjacent to cell towers, I can see LTE working for them. If anything for remote receive?

Not remote receive. It's an either/or thing. If the radio can hear the trunking control channel and the bit error rate is good, it'll use radio. If the control channel isn't there (either out of range, BER high or out of service) the radio uses LTE data to get the voice packets back into the P25 core and onto the rest of the system.

I'm going to stay in bounds here, but the video I watched of the Deputy Commissioner, she sounded gleeful that they were going encrypted. Not much happens on CHP that requires encryption. But that's the way it goes. It is fortunate that the system I am building is more fire related. CHP was just a bonus.

Encryption has been needed for a long time. Trying to convert the entire low band system to digital was going to be expensive. They played with it and it's entirely possible, but it made more financial sense to roll out a common statewide system.

 

[mmckenna]

This is all new to me. I would think they'd have been able to make a filter by now.

It's easy to filter the DC power. It's a bit more of a challenge to filter the vehicle.

But, there's a couple of issues that complicate things:
-It's not just the vehicle, it's all the electronics that get added to it. But, yeah, the vehicle is a major portion of that. The Fords have an issue with that. So do the Dodges. Chevys used to have notoriously noisy fuel pumps. As agencies moved away from low band, there was less focus on that. Higher bands don't have the noise issues that low band does.
-It's all the -other- vehicles that would be a challenge, also. Wasn't uncommon, back in the day, to get your CB radio running nice and clean in the car, only to have someone drive up next to you that would completely overwhelm your radio with noise from their car.

 

[wtp]

years ago i used to put a scanner in my car and had some ignition noise.
so i bought some resistor plugs AND wires, it worked fine.
by a friend remarked "i am surprised you get any spark at all" !

 

[HappilyRetired]

Depends too much on atmospheric conditions.
Also, CHP can't drive around with huge directional antennas on their cars hooked up to a 1,500watt amplifier. One, it's physically impossible. Two, FCC has limits on ERP, as these frequencies were at one time used by other states.

Kind of hard to do much with low band and a manageable size antenna. Also the same reason why CHP doesn't carry portable low band radios.



Yeah, HF is amazing. Add ALE, and you've got an almost fool proof communications system. Comes back to the antennas, though. Driving around with a 12 foot long whip on a car is a bit of a challenge. Makes them much easier to spot, though….



That's the beauty of trunking. I've got 450 users on a 5 channel trunked system and it is extremely rare to have enough congestion to cause issues. Rare as in a few seconds a year.

Mr. Erlang did a nice job figuring it out for telephone networks. Since trunking system are just RF based phone systems, it's pretty easy to figure out how many trunks you need on the system to handle calls:

Erlang (unit) - Wikipedia

en.wikipedia.org

Not remote receive. It's an either/or thing. If the radio can hear the trunking control channel and the bit error rate is good, it'll use radio. If the control channel isn't there (either out of range, BER high or out of service) the radio uses LTE data to get the voice packets back into the P25 core and onto the rest of the system.



Encryption has been needed for a long time. Trying to convert the entire low band system to digital was going to be expensive. They played with it and it's entirely possible, but it made more financial sense to roll out a common statewide system.

I knew that my comment about 1500 watts and a yagi pointed East would not come across as intended. Of course I know that's not possible. 🤣 it was really a treat as a budding new ham radio operator to work a contest. After all the years I spent at LAPD and the many thousands of hours I spent on the radio over that time, I was amazed at the amount of radio traffic coming over during the contest. Since we had such a powerful station with an antenna 100 feet up we were the ones being called. 6 meters was wide open! But I know that it's limited. As I had mentioned, when I was working intelligence in the military stationed overseas, it was not uncommon to hear us-based Highway Patrol and other things coming over on our radio frequencies. We had encryption back then. Still do. Most of the military stuff has gone satellite based anyway except for tactical.

Thank you for the pleasant manner in which you are trying to teach me. It's appreciated. I may be a little bit slow on some things but I'm doing my best.

 

[mmckenna]

Thank you for the pleasant manner in which you are trying to teach me. It's appreciated. I may be a little bit slow on some things but I'm doing my best.

Hey, no problem, this is a great discussion.

I've played on 6 meters a bit in the past, and always had fun on SSB. Amazing what a few watts could do.

 

[HappilyRetired]

Hey, no problem, this is a great discussion.

I've played on 6 meters a bit in the past, and always had fun on SSB. Amazing what a few watts could do.

It reminds me of the 1970s when I was a much younger man playing on CB radio and with four watts and a mediocre antenna one could talk to Australia. I have concluded that that's the same reason why when I was in Europe we could hear Stateside Public Safety on our military low band frequencies.

 

[AM909]

10 meters was a lot of fun. I had a converted CB and limited room to put up my sloping 10m dipole and still managed to get QRP WAS and about 50 countries with just a few watts on SSB. I even turned it down to 1W for QRPP CW and got a couple dozen states. Nevada, Idaho, and Arizona were last, of course, by many months, since they were too close. Spring E-skip got it done eventually.

All that long-distance skip is mostly a pain, though, for commercial low-band users.

 

[DeoVindice]

The radios they use will cover VHF Low, VHF High, UHF, 700MHz and 800MHz.
Currently that is done using the 4 stacks of RF decks from Kenwood/EF Johnson.
CHP is currently trailing the L3 Harris XL-200M in a couple of motorcycles in Sacramento, I believe.

And while the current VHF low analog system won't support the encryption they need. CRIS will absolutely support AES256, as required. One of the many reasons that the state is going to CRIS is specifically so they can utilize AES256 for law enforcement users.

The downside of going with Viking rather than NX is the lack of support for NXDN on VM7630H low band bricks with current firmware. Of course, equivalent Viking and NX models share FCC IDs so it is already type-accepted for NXDN. If CHP requests it, it will be implemented.

I met with my Harris rep on Thursday and we were talking about that. I know they've been trialing it on a few of the motorcycles recently.

Harris is supposed to be releasing an update that relates to MCPTT and BeON in the next month or two. Waiting to see what it'll do.

The VP8000 already seems to support TMS and most other data services being routed over Wi-Fi, and there is talk of a broadband voice gateway feature as well. Expect a new Viking mobile within the next few months - personally, I expect it will not have an integrated LTE modem and will rely on a Cradlepoint or similar for broadband connectivity, but that's just speculation. Either way, it's coming.

 

[mmckenna]

The downside of going with Viking rather than NX is the lack of support for NXDN on VM7630H low band bricks with current firmware. Of course, equivalent Viking and NX models share FCC IDs so it is already type-accepted for NXDN. If CHP requests it, it will be implemented.

CHP played with low band NXDN for a bit:

The VP8000 already seems to support TMS and most other data services being routed over Wi-Fi, and there is talk of a broadband voice gateway feature as well. Expect a new Viking mobile within the next few months - personally, I expect it will not have an integrated LTE modem and will rely on a Cradlepoint or similar for broadband connectivity, but that's just speculation. Either way, it's coming.

I've heard that, something along the lines of what BK is doing.

 

[AM909]

CHP played with low band NXDN for a bit:
...

Any idea of the tech specs? Seems like there would be a number of options with those wide 20 kHz channels.

 

[mmckenna]

Any idea of the tech specs? Seems like there would be a number of options with those wide 20 kHz channels.

Inside that box was two Kenwood NX-5600H RF decks. I believe they were running just plain 'ol 6.25KHz NXDN.

 

[DeoVindice]

Any idea of the tech specs? Seems like there would be a number of options with those wide 20 kHz channels.

12.5kHz with standard NXDN9600 features including software DES. Emissions designator 8K30F1E for voice.

 

[f40ph]

When I looked at CRIS I couldn't understand how so few repeater sites could handle all of the radio traffic from multiple agencies.

Remember with a smartzone trunking system, the only cells/towers that repeat radio traffic are ones that have a user in the area actually sitting on that specific channel. For example, in SB County, in the more remote Baker (or Trona) areas, the system only has a handful of repeaters (usually no more than 5). Yet with many active talkgroups countywide, the system doesn't "busy out". There are over 300 talkgroups on the system according to the RR database but VERY few radios in the local area and (for example) even though San Bernardino PD has several channels that are very active on the system, NONE of their users are in the Baker (or Trona) area to cause the towers to repeat SBPD radio traffic.

 

[brendan3]

Besides CHP El Cajon where else in the state are they primarily talking on a RCS system?

 

[nokones]

CRIS has been in the works since the early 2000s and the plan has always been a mixture of 700 MHz in the area where the use of the spectrum made financially and technically sense, and use a 150 MHz system in the remote areas in order to provide adequate radio coverage for public/officer's safety.

In the very early 80s, the CHP and CalTrans conducted a comprehensive 800 MHz radio propagation study and learned that in the remote areas in Northern California where there are pine trees, and other high foliage trees, the foliage, especially the wet pine needles, became problematic for radio coverage because the pine tree needles were essentially the same length as the 800 MHz wave length.

After the plan was adopted, the issues became funding, the time to develop the additional remote radio sites, and political support. The half a billion dollar CHPERS project came about in 2004/2005 because the existing CHP remote and mobile radio equipment was already approaching the age of 20 years for the mobiles and 30+ years for a majority of the fixed system with no available parts to repair, and the number mobile radios were in short supply for both the enforcement sedans and Motorcycles. The CHP had a standard to keep the mobile fleet of radios the same and not mix different types of radios for Officer's safety.

Also, the lack of vehicle interior space for additional electronic components and radio interoperability is what drove the CPVE (Consolidated Patrol Vehicle Environment) project and was combined into the overall CHPERS (California Highway Patrol Enhanced Radio System) project for the purpose of seeking funding over 5 years for the program.

The CHP had to do something at that time because CRIS was a long term plan, not short term, so the CHP had to act quickly, and they were able to get the support of Gov. Schwarzenegger and the State Legislators for CHPERS in the interim. Finally, it appears that CRIS is coming to fruition. Its been a long time coming to get CHP off of Low-Band ever since the late 70s.

 

[ScannerDude244]

Did they ever get to testing in Sacramento with the new APX next raidos?

 

[brendan3]

CRIS has been in the works since the early 2000s

So CRIS is the only other trunked network they operate besides San Diego RCS?

 

[nokones]

The El Cajon Area is the only CHP area operating on a local allied agency system for primary communications. Some Areas have access to their respective local allied agency systems for radio interoperability only on a secondary basis. Only a couple of Units will carry a second portable for those secondary communications.

El Cajon went on RCS because when the Low-Band Simulcast system was turned on the System never worked well. The "Gold" simulcast system was never properly engineered, actually was never engineered for similcast. The project engineer wasn't proficient in Simulcast thus they just installed the equipment at the existing sites and the system could never be properly phased.

The Officers complained of the poor communications and entered into an agreement with the County to use RCS. A great effort was made to fix the problems but it was nothing more than trying to polish a turd. Additional sites were required and some sites had to be turned off to make it phase properly. Because, the additional station equipment was no longer available and there were no spare stations, the point to fix the system was no longer practical.