Relay Input Frequencies

[Dave_D]

Repeater Input Frequencies

Hi all,

Why do the Common Public Safety channels show input frequencies for channels of type "R" (Repeater) but no input frequencies on channels of type "BM" (Base/Mobile)?

Is it not true that mobile radios communicating on 453.2125, for example, will transmit on 458.2125? Or does type "BM" suggest simplex operation in the absense of a repeater? Something else?

Any advice is greatly appreciated.

Dave

 

[blackacid]

Radios will transmit on the input freq if they are using the repeater. They can also have the simplex "BM" channel in it so that they can talk mobile to mobile for when they are close to each other and don't want to tie up the repeater or if a repeater isn't in range. So what you were thinking is correct.

 

[SkipSanders]

Base/Mobile means just that. The channel has base radios (radios at fixed locations), and mobile radios, on it.

The base may be at the police/whatever station, antenna on roof, or it may be remotely controlled (more common, if it has to cover a large area) and be off on a mountaintop somewhere, with the audio linked to the base operator by phone or microwave.

Even for 'repeater' stations, the base may actually be linked by phone or microwave to the 'repeater' rather than by the input, so they can guarantee that they control it if they want to talk.