Since no one else answered your question, I'll give it a shot. The base station is controlled with a microwave uplink from the comm center, and the receiver audio goes back to the comm center on the microwave downlink. Since the mobile traffic is not repeated (full duplex) over the dispatch frequency, you won't hear the mobile unit's traffic unless you have a good low band antenna and you are relatively close to the mobile unit transmitting.
The low band system is semi-duplex for car-to-base and base-to-car. In other words, the base station transmits on one frequency, receives on another, but the received traffic is not repeated. When units talk car-to-car, they are able to switch to a base station transmit frequency to talk, and that mode is simplex and is referred to as "3 way". The pair for Troop F is 42.600 for base-to-car and 42.660 for car-to-base. "3 way" or car-to-car is 42.600 simplex.
Look in the database and you'll find the respective frequency pairs that each comm center uses to communicate with the cars on low band. There are 9 base station pairs and one simplex Events channel which is called Channel 19. That one gets a good bit of use in some areas.
The 800 MHz trunked radio system called VIPER has already superseded the low band system in Troop A, and also some areas in other troop zones. Eventually VIPER will supersede the rest of the low band system as the VIPER system is completed, and low band will be done away with.