Communicator Recommendation?

wa8yxm wrote:
...,As a Ham Radio operator I have worked Duplex many times (Two frequencies) and depending on where I am full duplex (Where you can cut in while I'm talking) is possible. In fact when I was working MY radio (The Dispatcher's radio) was full duplex.. Car radios are not....

you may be thinking of semi-duplex or two-frequency simplex. I worked 35-years in public safety communications and know of no full duplex radio systems. I've been retired nearly m9-years now and maybe there have been advances in trunking since I left...don't know. educate me if that's the case.

when i was dispatching on one of our conventional 470-Mhz repeater channels I could key down and stay keyed down and occasionally would when traffic was crazy busy. it was a method of maintaining control. I would be able to hear all incoming traffic but the other mobile units would not as I had the repeat audio tied up. let's say that while I was giving out a dispatch a unit on the street experienced an emergency. while I was talking that officer could key his mic and call in. i'd hear him because the inbound audio was coming to me over the phone line or microwave link. but nobody else would hear him because I had the repeat audio tied up. that's still not full duplex because the street officer would have to unkey his mic in order to hear my reply.

in normal operations (I talk/they listen or they talk/I listen) if I had an emergency broadcast to give I could key down over a unit calling in to make the broadcast and every mobile unit with a radio in receive mode would hear me...everyone except the unit who was calling in. that's because when I transmitted I was keying the transmitter directly again via phone line or microwave link.

for years the Illinois state police ran semi-duplex ops on 42 Mhz. the cars would transmit on freq X and listen on freq Y. the base would transmit on freq Y and listen on freq X. full duplex was not possible because even though the car and dispatcher were on separate frequencies the receiver on the squad's radio was cut out while the officer was transmitting on frequency X. the only way to operate full duplex was if the squad was outfitted with a second receiver listening to frequency Y and the base dispatcher had a second receiver listening to freq X...and that just wasn't the case. maybe some jurisdictions did that. you're right in the sense that full duplex can be accomplished with 4-radios but it's just not practical.

IMO hand signals are still the best way. if you're pulling in after dark the driver and passenger should get out and inspect the site and then, using a flashlight, agree on a set of signals.