Question for CHP

[leitung]

I have CHP in sacramento as 42.1200 and 42.2000. I mainly listen to Sac Sheriff north on the County trunked system ID 61552. Thankfully I know all of the 9 codes so it makes it easy for me to understand. It's funny because my dad listens to it and doesn't understand the traffic one bit. Like the other night...

"BEEP BEEP.. all northwest sector units, 415-G in progress, (insert address), henry-23, sam-23, henry-12 respond code 3"
"henry-23 924"
"sam-23 924"
"henry-12 924"
"Control from STAR 5 do you need cover?"
"Afirm"

I am sitting infront of the scanner bouncing around like a retard going "action!" "action!"

Soon after,
"henry-23 906, I got one running, 1 HMA, northbound from Palm"

Me: Hell yeah, go get em!

My dad: (I swear he sounded just like towelie) "I have no idea whats going on..."
It takes getting used to listening to it, and really paying attention to whats going on. You also need know the codes. Thats part of it.
I run a Uniden BC898T 500 channel scanner with Trunktracker III. I have a discone antenna on a 5 foot pole on the roof of my shed.

[leitung]

A Beginner's Guide to the CHP Radio System:
The CHP employs two frequencies for communications between units in the field and their dispatch centers. One frequency is used by base stations, located at electronic sites, most of which are placed on mountain peaks or other high positions. Cars, or mobile units, use a second frequency to talk with these base stations. On the list below the base frequency is shown as the "frequency" and the mobile frequency is shown as "input." It is important to realize that base stations transmit from higher elevations and at much greater power than mobile units do. For this reason the base frequency can be heard over long distances, while the lower powered ground level mobile units can only be received if they are close by. The dispatch centers use one or more electronic sites to communicate with mobile units. Remember that high locations are ideal for radio reception as they can "see" more territory than ground level sites. This is why the dispatcher can receive most of the mobile traffic, while the scanner listener cannot. Electronic sites are linked via microwave or 72 MHz frequencies and the dispatcher's console is controlled by a type of computer that chooses the best signal to send to the dispatcher if more than one site is receiving a mobile unit's signal at the same time. This computer is called a voter, as the selection among multiple sites is "voted" for the best signal. When transmitting to a mobile unit the dispatcher can choose the electronic site they want to use, and normally choose the same site the voter chose when replying to a mobile unit. This is why you may hear the base frequency come in well at times when a nearby site is being used and not so well when another, more distant site is being used. When units want to communicate directly with each other, commonly referred to as "direct" or "car to car", they both switch their radios to another channel where the radio is both receiving and transmitting on the base frequency. One disadvantage to this is the cars can have the same experience that scanner listeners have, which is that they cannot hear other mobile units that are located some distance away.

In some locations within the state, mostly in urban areas, and mostly in southern California, the mobile frequency is patched to the base frequency on the most often used electronic site within a dispatch area. Cars are now able to hear each other from longer distances that they could before. This works the best in dispatch areas that are small and mostly urban as in these areas most mobile units can receive the same electronic site. In rural areas the dispatch area can be quite large with as many as 6-12 sites and mobile units may only be in range of one of those sites. Since the advantage of having the other mobile units hear each other is lost, the mobile traffic is not transmitted over the base frequency in rural areas.

That should explain it somewhat..

San Diego office should be on 39.4000 with input on 42.6600

[dasmi]

Yep. Lots of traffic on 39.4. 42.66 is quieter, cause I'm rarely near a CHP cruiser that's transmitting.

[proudamerican831]

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