The reason I came and asked this question to begin with was that I came across a website that said specifically that CHP was installing P25 capable equipment. For the life of me I cannot find that website again. I didn't think to bookmark it because I didn't think it was really going to be an issue. I don't know what goes into building these radios and I am still working on getting my ham license. I'm a complete rookie. I know what a repeater is and how they work in theory but actually building one is beyond me.
Yeah, there's the other 700MHz P25 stuff at the stations, but it's low power. Unless you are close to a station, you likely won't hear it. You could pick up the mobile extenders on 700MHz P25, but again, only if they are close by. The mobile extenders are only intended for short range.
The frequencies used by CHP are close to the Amateur Radio 6 meter band, so some of what you'll learn will apply.
I do know from my reading that low-band is really an underused band except for municipal agencies like utilities, the military, Department of Energy and a few others I found. I know that the band has issues with noise and when skip is in it can be unreliable. I know the band has the capability of being long-range compared to the others that are relatively short-range like 800. I've learned that they put those systems together kind of like large area cell phone systems. That was another thing I read was from the FCC instructing system builders to utilize lower power, shorter range but multisite systems. I guess because they're running out of frequencies. But with low-band being so unpopular I guess it's why nobody makes repeaters.
Yeah, low band has some drawbacks. Portable low band radios are hard to make work well. The antennas would need to be physically long to work well, and the radio chassis doesn't provide a very good counterpoise. That's why CHP uses the mobile extenders. Back many years ago they were using VHF for that system, 154.905, if I recall correctly. It was analog and easily heard on most scanners, so if you kept that frequency in your radio, you'd always know if there was a CHP car working locally.
Low band suffers from a high noise floor, and like you said, when the atmospheric conditions are right it can carry very far. Not uncommon for people in the mid-west or east coast to pick up CHP traffic when conditions are right.
There are still companies that make low band repeaters. They just are not very common. There is at least one company making P25 capable low band repeaters.
The point I'm getting at is that I understand that there aren't really manufacturers and so your point about repeaters is accepted. My ham radio Elmer took me to a repeater site and and I walked into this building and I was looking at all this stuff and like okay. What's it all do? LOL. I saw Motorola radios and various other things that were put together as repeaters. I won't make such an absurd statement is to say that a state agency would take mobile radios and make repeaters out of them but at the same time I can imagine that for enough money Kenwood could do it.
Amateurs will often make repeaters out of a pair of mobile radios set up back to back. It can work well if the power is turned down and there is good air flow. Commercial two way radios are usually designed around the 90-5-5 rule. 90% sitting doing nothing. 5% receiving, 5% transmitting. Much more and heat becomes a challenge. Not an insurmountable challenge, but something that needs to be addressed.
On the flip side, amateurs can be quite long winded and tie up repeaters nearly 100% transmit time when they are really going, so using a commercial mobile requires bringing the TX power down and adding good airflow over the heat sinks to keep them healthy.
Kenwood used to make a low band repeater built off their TK-690 mobile. They cranked the power way down and used an external power amplifier that was larger, had bigger heat sinks and fans. They could do the same thing with the NX-5600 easily. I haven't seen anything from Kenwood to suggest they are doing that, but maybe they just haven't told us.
In my research I came across the fact that CHP has to put in or update 277 sites as part of their new digital operations and I know that they have more than one channel at each site that's a repeater. That means they could need a couple thousand repeaters. I would think that once again when it comes down to money Kenwood could easily build the repeaters or under the EF Johnson name? I don't know who EF Johnson is. I remember back when I was a kid my uncle had a Johnson CB radio. It was like this six channel box the size of a toolbox. My overall point is that I don't think that given the directives by APCO that law enforcement agencies switch to P25 that CHP isn't headed in that direction. I didn't bookmark that page either. Like you said, it could be as simple as a firmware upgrade that I already know from checking out scanners it's a simple process. I'm sure it's not quite as simple on a two-way radio but possible.
EFJ is a big company and they were merged with Kenwood many years ago. EFJ has made a lot of radios over their time, CB, amateur, commercial, etc. Story is Kenwood bought up EFJ to get their P25 infrastructure products. Kenwood does sell some P25 repeaters under their name, but if you were to buy a big system, it would be EFJ. Some of the products are identical, just different firmware. EFJ has some licenses to sell Motorola SmartZone compatible radios, so that has been kept separate from the Kenwood branded products.
APCO is an industry group and does develop standards, but they do not have the authority to require agencies to do anything with their radio systems. The P25 stuff has been driven by the federal government by requiring radios purchased with federal grant funds be P25 capable. It does not require agencies use P25. It's been done in the name of interoperability. If an agency doesn't purchase radios with federal grant funds, then there is no requirement to go P25. Many agencies have gone to DMR or NXDN for their needs. It's cheaper, and federal grant money can be hard to get.
I did read up on NXDN and see that it is a technology invented by Kenwood and Icom and it's supposed to sound better than P25. But P25 had become the public safety standard. Again the point being as I return to the statement that I'm sure Kenwood could build P25 repeaters.
Yes. Like I said, the TKR-690 repeater was based off the TK-690 mobile cranked down to lower power, added an external amplifier and control system. No reason at all that Kenwood couldn't do that with the NX-5600, and update firmware to allow P25.
But there are already other companies that produce P25 capable low band repeaters. So, not a technical challenge, they just need someone to buy the stuff. So far no word from CHP on them upgrading the Low Band network.
My Elmer was telling me that most repeaters these days are nothing but a couple of mobiles put into a box with a controller. Like the DMR radios he was showing me. They look fancy on the outside but he said just what I wrote. Just a couple of mobiles put inside of a box.
On the amateur and low end commercial side, absolutely.
On the higher tier commercial and public safety side, repeaters are specifically built products that are designed from the ground up to be a repeater. The control interfaces are different, they often have higher tolerance oscillators, more heat sinks, separate RX and TX antenna ports, different power supplies, etc.
My guess is that Kenwood has the building blocks to build low-band repeaters with P25. But what do I know? My biggest concern is whether or not they employ encryption which doesn't require from what I've read P25 or any other digital method.
Yes, they absolutely do have what they need to make them. There is/was at least one other manufacturer selling P25 capable low band repeaters as of a few years ago, and Midland has what they need to make them also.
Not a stretch of the imagination that CHP might go that way, but so far nothing has been said to suggest they are moving in that direction.
While P25 can absolutely be used on Low Band, how it would respond to a high noise floor and possible skip interference would need to be looked at.
