What is the purpose of Control 1?

[gmclam]

Stanislaus County Fire Dispatch is on 153.770 MHz. It appears to also be "repeated" on 453.525 MHz, named as "Control 1". Often there are repeaters on VHF because the main dispatch is 800 MHz or something like that. But the signal on 153.770 MHz is quite strong and seems to overlap the coverage of Control 1.

So I wonder what is the purpose/function of Control 1?

 

[Kingscup]

Are you only hearing dispatch and not units on control 1? Control 1 may only be used for station dispatching only. Stations only hear dispatch and no unit traffic. Fresno fire had/has this setup. That's all I can think of off the top of my head.

 

[gmclam]

Are you only hearing dispatch and not units on control 1?

Yes. No mobiles.

Control 1 may only be used for station dispatching only. Stations only hear dispatch and no unit traffic. Fresno fire had/has this setup. That's all I can think of off the top of my head.

No wonder there is a shortage of spectrum.

 

[Markinsac]

In a word, legacy equipment support. The stations may have some older equipment in place for the dispatch tone and printing. It can be expensive to move this over to a trunked system. It also affords some redundancy due to geographic and/or trunking capacity/maintenance issues. VHF coverage given a specific power level is going to be greater.

The mobile units will come up on whatever tactical frequency they are using for the event, and can still monitor Control 1 for assignments when mobile.

 

[gmclam]

Read my first post again

In a word, legacy equipment support. The stations may have some older equipment in place for the dispatch tone and printing. It can be expensive to move this over to a trunked system.

But the main dispatch is 153.770 MHz and is NOT a trunked frequency. The main dispatch channel has a greater converage area than 453.525 MHz.

 

[whiskeytango]

does the 150 and the 400 transmit from the same location?

 

[Markinsac]

But the main dispatch is 153.770 MHz and is NOT a trunked frequency. The main dispatch channel has a greater converage area than 453.525 MHz.

My point exactly - you want maximum coverage for all the stations that might be in outlying areas. I'm guessing that the radios in the trucks for the trunking system are set to high power.

The difference in coverage given a power setting isn't as dramatic between 150 and 450 Mhz as it would be between either of those and an 800 Mhz system. As long as the trunk system tower has enough height to see the signal, it should work fairly well.

Also, if personnel carry pagers in that area, 150 Mhz pagers are still in good supply and get good reception.

 

[gmclam]

Stanislaus Control 1

My point exactly - you want maximum coverage for all the stations that might be in outlying areas. I'm guessing that the radios in the trucks for the trunking system are set to high power.

Your point is missed on me. I was looking for someone that KNOWS why this is the situation, not a bunch of guesses.

The difference in coverage given a power setting isn't as dramatic between 150 and 450 Mhz as it would be between either of those and an 800 Mhz system. As long as the trunk system tower has enough height to see the signal, it should work fairly well.

You are totally off the mark. There is no trunk system here, and there is a big difference in coverage between signals in those two bands. And since VHF has the better coverage, I see no need for the UHF repeater.

Also, if personnel carry pagers in that area, 150 Mhz pagers are still in good supply and get good reception.

Yup, another reason the UHF signal is not needed.

 

[Kingscup]

Your point is missed on me. I was looking for someone that KNOWS why this is the situation, not a bunch of guesses.

...

Then you should be contacting them and getting the correct answer rather then asking on an internet forum. I am sorry I wasted my time.

 

[gmclam]

Users of the system are not likely to know. There are a lot of people on this site that know these kinds of technical details first hand.

 

[clanusb]

The only reason I can think of for having that fire dispatch repeated on a UHF freq is if the county contracts its EMS services to a private company who mainly uses the UHF EMS freqs.

It looks like AMR does the county EMS...even though they have a DSP on 152.41250, it looks like their portables and hospital med nets are on UHF. My guess is that they are issued UHF portables, and get the repeated fire dispatch freq, just so they can have a heads up?

it isnt cross banded so that EMS and Fire can talk to each other, is it?