Newbie Question Conventional Freqs.

[BuiltonAsus]

I was just wondering how do people keep everything straight when it comes to conventional freqs. I noticed that in many counties conventional freqs are shared. In Washtenaw Co. there are a few freqs that are shared by all the fire dispatch centers which makes sense.

But if you look at Oakland or Wayne, many conventional freqs are shared by departments that aren't even related such as a fire dispatch freq. is shared with a police dispatch. Is it just because it's a lower freq. that they know it won't cause interference?

I also am pretty new in understanding tone-outs, and what the PL codes mean. Actually I know nothing about tone-outs. Sometimes a freq. will have different PL numbers. Is this the only way to tell the difference?

That's why I love TRS, since each has their own TG, which is very simple and easy to understand. Why can't everything be this nice.

It's late, and I think I am feeling the effects of being up, but I am delaying work. Hobbies before job right?????........

[k8tmk]

I can answer a couple of your questions.

Tone-outs are special tones that are used to alert certain pagers. For example, a particular county may have all of its fire departments pagers on one frequency, and have a common dispatcher. The dispatcher can send out these special codes to alert only those firemen that are needed. The pagers all remain quiet (squelched) until it decodes the tones that are associated with it. The correct codes will open the squelch and allow the person to hear the message. The other pagers will not hear anything.

PL codes are somewhat similar to tone-outs. PL (or private line) is a low-pitched subaudible tone that is always present whenever a particular transmitter is transmitting. If you listen closely, you can ofter hear the hum of the PL tone in the background. The purpose of a PL is to keep noise, interference from distant stations, etc. from becoming annoying when the user only wants to hear his own agency's radio traffic. In very small communities, several agencies that don't use their 2-way radios much may fund a single repeater that they all can share. Each agency would then have its own PL (there are several different ones), and wouldn't be bothered by other agencies radio traffic.

Hope this helps.

Randy