WA Radio Scanner Users' Group

1

I'm guessing you're talking about Selective calling (selcall). Westrail, bus companies and Chubb security use this alot. It sounds like this.

When transmitted before or after every transmission It's a way that the base can know what radio has just transmitted, usually called ANI. (usually to track radio abuse or for emergencies - a sort of two-way radio version of caller-ID)

Some networks are set up so portables can signal their base using selcall and the base will still hear them call - most radios I've seen beep madly or ring like a telephone when called - even if the base isn't necessarily listening to their channel.

For example, Westrail base will hear selcalls from, say, transit security to them even though they have a dozen radios to monitor and probably have the volume down on the security channel most of the time.

UHF CBers also use Selcall for radio to radio calling.

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Sorry i probably should have made it more clear...

Jmmw wrote:I only really listen to the police channels..

Are you listening right now to 468.4750?

Ahh ok. Listening now but not sure if I heard the sound you mean. High pitched noises on the police channels are probably one of three things:

A screetch that sounds like a telephone modem followed by a high-pitched whistle is DVP (encrypted). Rare on general operational channels and is usually used on ch 3 and 9.

If you're hearing a clicking, beeping noise as a vehicle lets go of his push to talk button or if he's not getting a good signal into the repeater and you hear his voice mixed with a fast clicking and beeping then that sound is coming from the repeater receiver's CTCSS tone decoder. It's normal.

A high-pitched, fast sounding (i.e. much faster than selcall) set of tones on VKI channels is usually data from an alarm. Probably the repeater isn't happy for some reason and it's letting VKI know. Might've lost mains power or someone's trying to break in to steal it ... :-)

Gavin
VK6HGR

ahhh i think it might have been the second one, thanks. On that channel is the shooting that happened an hour or so ago in lockridge JFYI