Is California the last state to keep the low band
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Can Barely Hear California Highway Patrol (Low Band)
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CNRSW72
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What exactly do you mean by P25 system and how are their extenders using it?
They went to the 700 p25 a few years back, they started that and also to keep up and using it for mutual aid so all they do is click over on there ht's
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CNRSW72
Member
I am aware that they have 700 extenders but the post above me indicated they have a P25 “system”. There is no “system” as far as the infrastructure goes. They have voted low band base stations and UHF analog repeaters statewide. There is a stand-alone P25 700 repeater in LA but it is not tied to a core. And as far as their cars go, they do, for the most part, use 700 extenders to control the CPVE in their units.
What frequency is that one? I can't find a reference to it in the database.
Yeah I didn't think actual traffic dropped out of Chico in favor of MDC or something. Figured it's something on my end that's deaf, most likely the Whistler - they're notorious for being deaf. 
or Chico favors a transmitter on the east side for I5 calls instead of St. John on the west side. I'll run it and the 15X side by side on my run down I5 and back in a few weeks. I am worried of what I've been missing all this time...
or Chico favors a transmitter on the east side for I5 calls instead of St. John on the west side. I'll run it and the 15X side by side on my run down I5 and back in a few weeks. I am worried of what I've been missing all this time...
Southern Div, Base 2. It's on the standard base freq for Southern but a different NAC. I think it was found during the Rose Parade this year.
Good to know. Missed that one. Thanks.
krazybob
Member
I follow CHP in Southern California very closely. Because of my location at the top of the mountain in the San Bernardino's I can hear San Diego like it was next door. I can't hear Santa Barbara because they dispatch out of the office or Ventura that dispatches off of Red Mountain. The Angeles National Forest to gets in the way.
CHP has not begun switching to a 700MHz P25 digital system. Although CHP stations have 700 MHz that is for unit to station and vice-versa traffic as well as fail-over in the event of an outage from the major communication centers. Of course they have extenders which sound like crap. They have no range and often times it sounds like an extender repeater is doubling with another.
I talk frequently with a couple of the radio technicians that work a vault that's on one of the mountains my repeaters are on. They've indicated that they have no expectation of leaving low-band.
Except for the major metropolitan areas of San Francisco, Los Angeles, and San Diego switching to 700 / 800 would seriously hamper communications. Most of the areas that CHP covers are not metropolitan and that includes where I live in the San Bernardino Mountains. Even up here they have I believe it is four sites to cover the entire mountain range. One is Onyx Summit that recently had a fire that burned the main building to the ground plus one outbuilding. CHP uses fireproof buildings and doesn't seem to have skipped a beat. They are on a repeater and are set up for simulcast.
Other areas like Santa Ana are on simulcast but also use voted steering. I'm not quite sure why they do that but you'll notice it when you're listening to CHP loud and clear and suddenly you can barely hear them. Capistrano comes in loud and clear.
Simulcasting is not as easy on low band and was the major sticking point when CHP and the southern division finally went to repeaters. Orange County was already completely repeater but Los Angeles was the hold out. Once you move out past the San Bernardino Mountains going north you're into Victorville and parts unknown where one transmitter and numerous voted receive sites cover vast areas of the desert. I don't know why not but they are still using split frequency duplex. I can hear the mobiles talking on channel 2 from time to time.
I can't speak to those of you in Northern California and your experience. I know that you can use the Antennacraft ST-2 which has quarter wavelength elements for low band. If you use a fiberglass pole to get it up above those elements and then the rest can be standard pipe you'll find omnidirectional of coverage on lobe and is quite good.
Antennacraft ST2 Scanner Antenna, Antenna Craft ST-2
But but that's not how I roll. I have a home built coaxial sleeve antenna that you can find Illustrated on the Kreco antenna site. they are one provider used by CHP. CHP also uses side-mounted folded dipoles.
Kreco Antennas - Welcome
I built my own coaxial sleeve antenna tuned for the center of the CHP frequencies. It kicks butt! I have it up in the air quite high and even when I lived in Metropolitan Los Angeles County I could hear Ventura down to San Diego and I could hear mobiles quite well before they were repeated. Using two scanners I could hear a pursuit quite well.
If you aren't into building your own antennas that's when the Antennacraft would be your best choice. I used to sell them on eBay and they would go fast. And it's multiband. If you were to build a coaxial sleeve antenna all you would need would be a diplexer that would separate everything below 100 MHz and above.
I think you've CHP where do abandon lobe and they would go to VHF and utilize the same mountain tops that fish and game use plus of course they would add additional. Equipment is readily available for Motorola as well as Kenwood. The other brands are not really reliable. Fish and Game uses the Kenwood's unless they've changed recently.
If you want help building a coaxial sleeve low-band antenna get with me by PM and I can direct you from there. I put together a page with step by step instructions.
Essentially the purpose of voting is to select the correct mountain-top so the reply is best received by the car.
I happen to like the CHP's duplex low-band based system. Signals can travel quite the distance (although perhaps not through tunnels [lol]). The significant key for us listeners is to have the correct antenna, as mentioned here.
krazybob
Member
Thank you but I'm not sure what point you're making that I haven't already made?
As I mentioned, many areas use one primary transmitter site and multiple voted receive sites. They send the signal back over microwave or other radio means with a pilot tone. The signal-to-noise ratio of the feet is measured against that of others and the best site is sent to the repeater(s).
This could happen instantaneously and one minute you're on one repeater site and the next minute you're on another. Similar to how cell sites do a handoff to another cell site. Cell sites originally were intended to be built in a honeycomb type fashion where is you moved from one geographic area into another the handoff was automatic. It's gotten a lot more compact since then.
I run a SpectraTac receiver voter on my repeaters and they work fine. But I'm at VHF and UHF. Low band does not simulcast well.
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Simulcasting is attractive for scanner listeners, but has little utility for the CHP. Aside from problems keeping transmitters synchronized there is no need for all cars to hear all transmissions.
Kenwood makes the radios used by the CHP and as long as the CHP stays on low band, Kenwood will keep making the radios.
The technicians work for Kenwood, not the state. I know one (now retired) who serviced CHP and USFS radios in this area. He certainly knows how to set up simulcasting, but did not because there was no call for it.
Problems with low band reception are mainly due to antenna issues. At one time I had a 1/4 wave ground plane for 42Mhz. Worked better than anything I ever had. May build/buy a new one someday.
CHP will probably stay on low band. Given the areas and terrain they cover it makes good sense. Low band has fallen out of fashion, but it has many advantages in terms of coverage and propagation.
Kenwood makes the radios used by the CHP and as long as the CHP stays on low band, Kenwood will keep making the radios.
The technicians work for Kenwood, not the state. I know one (now retired) who serviced CHP and USFS radios in this area. He certainly knows how to set up simulcasting, but did not because there was no call for it.
Problems with low band reception are mainly due to antenna issues. At one time I had a 1/4 wave ground plane for 42Mhz. Worked better than anything I ever had. May build/buy a new one someday.
CHP will probably stay on low band. Given the areas and terrain they cover it makes good sense. Low band has fallen out of fashion, but it has many advantages in terms of coverage and propagation.
Santa Barbara dispatches off of Santa Ynez Peak and La Vigia Hill (above Santa Barbara City). Ventura also uses South Mountain.
CHP has lower transmitter power than in the old days. I used to hear San Diego in Santa Barbara like it was next door. Solar cycles are also a big factor. San Diego and Santa Barbara were on the Green. I also used to hear San Bernardino, Ventura, San Luis Obispo and El Centro on the Blue channel in the late sixties and early seventies.
My favorite low band story is from a visit I paid to the fire boat station in Seattle. They had an old low band system on 33.70Mhz. I remarked to the captain that Los Angels City Fire also used that frequency. He said, "I know, I talk to them sometimes." No PL in those days. Recently I met a fellow ham who worked with LAFD. They frequently talked to Seattle from their engine.
krazybob
Member
Radio reference shows Santa Barbara transmitting off a La Vigia Hill only. I expected that they were either on Santa Ines or Broadcast Peak but since the database only showed one I just stayed with that. I am more than happy to accept your response.
ULS License - Public Safety Pool, Conventional License - KMB524 - CALIFORNIA, STATE OF - Frequencies Summary
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Do they also service the Rangr radios that are still in use on the older BMW's, Kawasaki's and first batch of newer Harley's?
krazybob
Member
I thought they were still running Rangers for the most part. The Kenwood's are good but so are the Yaesu Vertex 5000 and 6000 series. I actually use a Vertex 4000 VHF L to monitor CHP.
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krazybob
Member
Here are the step by step instructions to building a coaxial sleeve antenna like CHP uses at many of its installations. Kreco is happy to sell it to them for over $800. The state buys it just like they buy the halfwave folded dipole that side mounts off of a tower.
This is the Kreco without the 3db skirt.
Or the side mounted folded dipole with up to 7db gain.
This is my home built version. This was the first try. I could have done better on the second try. I ended up using non metallic spray paint and sprayed the main body of the antenna green so that it would meld into the trees at my wife's idealic mountain Home.
6 Meter Repeater Antenna 1/2 Wave Coaxial Vertical Antenna Design
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This is the Kreco without the 3db skirt.
Or the side mounted folded dipole with up to 7db gain.
This is my home built version. This was the first try. I could have done better on the second try. I ended up using non metallic spray paint and sprayed the main body of the antenna green so that it would meld into the trees at my wife's idealic mountain Home.
6 Meter Repeater Antenna 1/2 Wave Coaxial Vertical Antenna Design
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Based on what?
The hardware is no more difficult to synchronize than any other frequency band, and because Doppler shift is a function of speed and frequency, a 40 MHz simulcast signal is much less impacted by Doppler shift than, say, 700 or 800 MHz.
Doppler shift is the bane of analog simulcast, particularly when the intended recipient is in a vehicle moving at freeway speed.
The 330 Watt and quarter kilowatt Micor upright, and GE Mastr stations are long gone. They have been replaced by 100 Watt solid state radios that occupy a few rack units. The quarter k's were almost the size of a refrigerator.
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