School Bus System

[bigredmachine]

I have a couple questions about the system that my local school district's buses use..
They have motorola radios that use 469 mhz as the input frequency and 464 mhz as the main frequency. I'm not sure how it works so I want to clarify. I understand that the mobile radios transmit on 469 to the repeater and the repeater broadcasts that signal on 464. When the buses leave the area for a field trip or whatnot how do they communicate? Do the radios automatically sense that there is no repeater main frequency so they just transmit and receive on 469 the whole time? Or do the radios transmit on both frequencies all of the time and whichever is received with a better signal is used?

Sorry for so many questions..I've just had a lot since getting my scanner!

Thanks. Sid

 

[Don_Burke]

I have a couple questions about the system that my local school district's buses use..
They have motorola radios that use 469 mhz as the input frequency and 464 mhz as the main frequency. I'm not sure how it works so I want to clarify. I understand that the mobile radios transmit on 469 to the repeater and the repeater broadcasts that signal on 464. When the buses leave the area for a field trip or whatnot how do they communicate? Do the radios automatically sense that there is no repeater main frequency so they just transmit and receive on 469 the whole time? Or do the radios transmit on both frequencies all of the time and whichever is received with a better signal is used?

Sorry for so many questions..I've just had a lot since getting my scanner!

Thanks. Sid

Normally, the mobiles are also set up to transmit and receive on the repeater output, usually as another channel position on the radio.

It would be rare to find a school bus system that switched automatically, although I have run a two meter rig set up to transmit on the repeater input and to listen on both the input and output. That worked pretty well in many situations.

Transmitting on both frequencies would just make a mess.

 

[N_Jay]

They probably just switch to "Channel 2" or "Talk-around", or "direct", and then transmit and receive on the repeater output frequency.

It is very common.

 

[bigredmachine]

so technically I should be able to put both of these freqs on a bank in my scanner, have it scan ning, and be able to get the best signal from where I happen to be. (if it happens to stop on the best one first)

 

[scanfan03]

so technically I should be able to put both of these freqs on a bank in my scanner, have it scan ning, and be able to get the best signal from where I happen to be. (if it happens to stop on the best one first)

Yes but you will only hear them on the 469 freq if you are close enough.

 

[Don_Burke]

so technically I should be able to put both of these freqs on a bank in my scanner, have it scan ning, and be able to get the best signal from where I happen to be. (if it happens to stop on the best one first)

I have several systems I scan that way. You may find yourself locking out one of them if it is marginal, but for the most part, it will run fine scanning both frequencies.

I have found it works a little better if it is set up so that the scanner hits the input first in the scan sequence.

 

[Astro25]

They will revert to channel 2. If it's anything like my old school, we had maxtracs, gm300's, m1225's, and even CM300's. Each radio had about 10 of the district's channels in it.


What school/area do you live in? It may be listed in the database for the exact frequency and PL or DPL tone.

 

[kb2vxa]

Hi Big and all,

You can end this speculation by looking them up in the FCC database. That will give you the particulars on the license and any restrictions. In most cases the mobiles' repeater input frequency use is limited to a particular radius around the control point and a talk around simplex frequency may be statewide or nationwide depending on the area they cover. License restrictions vary so this may not be the case, look it up.