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I have a friend that works for the D.O.T. on the radio mounted in his truck, he can flip a switch and choose the station he wants to talk to. Be it Nome, Kodiak, Anchorage, Soldotna, etc. all from the yard in Seward. My question is, how does this work? Does flipping the dial direct the transmission to different repeaters or something? Why doesn't my scanner pick up transmissions from all these places? I have heard the Seward DOT talking to Kodiak DOT claear as a bell. I've even heard radio tests of the ALMR emergency system from as far away as Oregon. Why aren't we constantly picking up signals from these places?

Thanks in advance