input freqs

[tbharper]

i cant remember but if you put input freqs in do you hear anything or is just for a repeater.my brain is on overload right know.

 

[BaLa]

i cant remember but if you put input freqs in do you hear anything or is just for a repeater.my brain is on overload right know.

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Whether or not you will hear anything, depends on how close you are to the unit transmitting, and of course how much power they have (mobile vs handheld).

The Input is the frequency a repeater listens on.

 

[RayAir]

A note regarding input frequencies- A police dept around here would say to "go local" and the repeater output would be silenced with voice communications taking place on the input freq. So if all you had programmed in your scanner was the repeater output you would miss the communication.

 

[ibagli]

A note regarding input frequencies- A police dept around here would say to "go local" and the repeater output would be silenced with voice communications taking place on the input freq. So if all you had programmed in your scanner was the repeater output you would miss the communication.

What was the purpose of doing that?

 

[gewecke]

Well put,with one small note. Several years ago this was once referred to as "talk-around". When encryption wasn't affordable or semi private channels were not in the radio,this was a popular
practice. Sometimes still used!

 

[Radio_Lady]

What was the purpose of doing that?

Probably for a bit of extra security, since almost nobody ever programs the input/uplink frequencies into their scanners.

Some years ago LAPD had three 453 MHz pairs assigned to some specialized divisions (Narcotics, Vice, Intelligence), but at the time the only encryption they had was the easily defeated voice inversion. In addition to the three repeater-select tones, "ST1" "ST2" and "ST3" and the typical output-frequency simplex (talk-around), they could switch to a no-PL setting on the repeater uplink frequency. The called it "ST4" so the other units would know they had to switch their RX to the uplink frequency. Not terribly secure, but it worked.

 

[SkipSanders]

Well, 'Talk Around' usually means simplex on the repeater OUTPUT frequency, but, otherwise, yes, it's an old 'trick' to use simplex on the repeater input (with no tone so the repeater doesn't repeat it) as a semi-secret channel.

The FBI used to use this a LOT at bank robberies, not so much for secrecy, as because the handheld units in the bank couldn't hit the repeater, so they'd use simplex on the input, the outside units could hear them (being nearby), and the outside units would still be repeated, so they could relay to base by just repeating the info themselves.

Of course, range to handheld/mobile units is rarely above 4-5 miles, unless you have a particularly high hill you're listening from.