How To Monitor Two or more Groups of Radios
Most radio systems start off as a single group of radios who all hear each other i.e. hear every call. This works fine for three or four radios but as the radio system grows to several radio some users find they don't want to listen to another group talking and prefer their radio to only sound for calls directed to them or to their Group.
For instance Maintenance staff normally will want to talk frequently amongst themselves. They will normally have no need to listen to Security staff and the Security staff will have no need to hear Maintenance. A supervisor however may want to hear both Maintenance and Security user Groups.
Analogue Radios. Give each Group a dedicated channel. e.g. Maintenance on Channel 1 and Security on Channel 2 then they will only hear their own group. They can call the other Group by changing channel (remembering to return to their own channel afterwards).
But what about the Supervisor? They can't be on both channels.
Solution: What they need to do is have their radio configured to be a Scanning Radio. which will allow them to monitor both groups.
Digital Radios. Most digital radios have been designed with this scenario in mind and indeed for most users this may be the main advantage of migrating to digital radios. Digital radios can be configured to make Private, Group and All-Calls using a system called Selective Calling.