CHP-Primary other than VHF-Lo?

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JoeyC

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monitor142

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I believe CHP's use of the San Diego RCS system is/was more or less a test to see how well the use of a local communications system would work out for their daily operations. They still have low band installed in SD and can use it any time.

A few key folks who watch the forums and are more involved with the background can advise further. They have been using RCS for many years.

-M142
 

JoeyC

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Yes, I heard that the test period came and went and they extended their use on the RCS indefinitely.

Funny how this agency has moved over to the dreaded digital and trunked that so many on these forums claim doesn't work, isn't reliable, etc. and have opted to stay even though the low-band radios still exist in their cars!
 

monitor142

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It goes without saying that every system is different. Radio is radio and it's always evolving and improvements are made when the funding is there. Look at the after action reports with the major fires in San Diego County and the numerous improvements that have been made to RCS since those fires. They still continue to make improvements such as modifying intellirepeater fill-in sites to simulcast and adding more physical RF channels to the trunked system for more capacity.

What works here may not work somewhere else. CHP in my County to the north has some trunked system access mainly at the dispatch center level and also in their aircraft. It works well along with non-800MHz improvements in the last few years that permit console patches to low band CLEMARS and other VHF and UHF channels. The 4th of July is a prime example where it is heavily used.

-M142
 

MotownJG

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CHP in the central valley has always been a puzzle to me. Live in Modesto - get dispatched out of Stockton. Drive to work in Merced, listen to CHP out of Atwater. One freq here, one freq there, figure it out? Not really, never said I was that smart. I rely on software............
 

gmclam

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C h p

Is there anywhere else in the state besides Border Division El Cajon office operating their PRIMARY dispatch operations on a system other than the 42 or 39mhz frequencies?
The fact as I understand it is that while they might be on a trunked system, their primary dispatch is still on VHF low in that area. In other words, they are on both bands.

The answer depends a little on what you're getting at. If you'd like to pick them up someplace other than VHF low, then you should also consider their microwave signals .. which are at about 72MHz & 75MHz. These are directional and you typically have to be in the path to pick them up though.
 

JoeyC

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The fact as I understand it is that while they might be on a trunked system, their primary dispatch is still on VHF low in that area. In other words, they are on both bands.

The answer depends a little on what you're getting at. If you'd like to pick them up someplace other than VHF low, then you should also consider their microwave signals .. which are at about 72MHz & 75MHz. These are directional and you typically have to be in the path to pick them up though.
No, the primary dispatch is not on the VHF low in that area, they have been on the RCS for several years and the GOLD1 channel has been silent for just as long. They are not simulcasting over both systems either and the only time GOLD1 is used I am guessing is where the TRS fails, which isn't in very many places based on the silence.

What I am getting at, is programming the state so that I will HEAR the CHP operating when I am in the area.

This is one of the weaknesses of this database in that when there are multiple frequencies/systems listed for an agency, it is often difficult to figure out just exactly what IS used primarily and what isn't - often leading to programming an enormous amount of data that isn't necessary. This is especially true when downloading through software or picking what to listen to through a menu of available items such as what the PSR800 library has to offer.
 

SCPD

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The fact as I understand it is that while they might be on a trunked system, their primary dispatch is still on VHF low in that area. In other words, they are on both bands.

The answer depends a little on what you're getting at. If you'd like to pick them up someplace other than VHF low, then you should also consider their microwave signals .. which are at about 72MHz & 75MHz. These are directional and you typically have to be in the path to pick them up though.
The 72 MHz frequencies are not microwave. At wave length more than 4 meters or approximately 12 feet they could hardly be considered microwave. A lot of scanners, especially the new ones, receive 72 MHz signals, but none receive the frequencies the State of California uses for linking electronic sites via microwave, which can often be as high as 20,000 MHz. In addition they cannot be received unless a dish is in the direct path of the transmission.

The 72 MHz frequencies are used when microwave cannot be used at a site. Typically these are sites without commercial power. Vertically polarized antennas reduce the width of the signals and one must be somewhat close to the path to receive them.
 

gmclam

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CHP @ 72 & 75 MHz

The 72 MHz frequencies are not microwave. At wave length more than 4 meters or approximately 12 feet they could hardly be considered microwave. ... Vertically polarized antennas reduce the width of the signals and one must be somewhat close to the path to receive them.
Yup. i thought someone might make a comment on this. Yes, technically not what we call microwave, but they are broadcasting with a narrow beam that is highly directional. It sounds funny to call it a "small wave" (and yes I realize it has a wavelength of about 13.6 feet).
 

techman210

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You really can't get THAT narrow of a beam with the current directional antennas. Most that I have seen in this "mid-VHF" band are just three elements. Similar to this model:

Kreco Antennas - Vertical Beam Antenna VB-40A

CHP in my neck of the woods links sites with a combination of leased-lines, microwaves (some State owned, some other agency owned) and 950 MHz digital MAS systems - which were analog mux 950 until a couple of years ago.
 

kma371

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Yup. i thought someone might make a comment on this. Yes, technically not what we call microwave, but they are broadcasting with a narrow beam that is highly directional. It sounds funny to call it a "small wave" (and yes I realize it has a wavelength of about 13.6 feet).
I get the 72Mhz links all the time. I dont believe I'm in any of the paths of their "narrow beams" so I don't think they are directional.


Sent from my iPhone 4 using Tapatalk
 

techman210

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By law, they have to be "directional". Unfortunately, there is no requirement for a minimum for beamwidth, or F/B ratio. Look at all the 800 MHz base stations in the SMR band that use little 3-element beam antennas. There is a forward lobe of energy.... just not much of one.

So the antennas are directional.... just not very directional.
 

SCPD

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The one 72 MHz link I was in range of (45 miles at Conway Summit) was beamed to the Sweetwater Electronic Site about 30 miles to northwest of Conway. I could pick this signal up and listen to mobile units at the state boundary at Topaz Lake. I was receiving the backside of this signal at about 165 degrees. I don't think one could call this a narrow beam.

The use of 72 MHz's for Sweetwater was discontinued once a power source for a microwave link was obtained. I'm not sure what it is as this site does not have commercial power.
 

ScannerDude244

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The one 72 MHz link I was in range of (45 miles at Conway Summit) was beamed to the Sweetwater Electronic Site about 30 miles to northwest of Conway. I could pick this signal up and listen to mobile units at the state boundary at Topaz Lake. I was receiving the backside of this signal at about 165 degrees. I don't think one could call this a narrow beam.

The use of 72 MHz's for Sweetwater was discontinued once a power source for a microwave link was obtained. I'm not sure what it is as this site does not have commercial power.
Yeah I can pick up 72Mhz up and down the Salinas valley no problem it's a real strong signal.
 
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