RRs use lots of "remote bases". one frequency out, NOT repeated.
Semi duplex (one way at a time), not full duplex (both sides can talk at the same time, like cell phones).
The UP may be using a system like the old NS system.
Dispatch out on one frequency/Trains back to dispatch on another frequency.
( NS in Piedmont North Carolina used a 160.245/160.830 frequency pair)
There are repeaters used in yards, and other places where many workers are close to each other, and need co-ordinate their work., people like hostlers, car inspectors, yard maintenance, etc
Railroads usually do not use repeaters on their road lines outside of yards.
RR dispatcher zones tend to be very long and linear.
A RR dispatch zone may be 250 miles long, but only 100 feet wide.
One single repeater would not work.
One dispatcher may be responsible for more than one zone possibly several hundred miles.
Each remote base in a dispatch zone, and its service area is about 20 miles or so.
In very busy areas or hilly areas, the remote bases may be more closely spaced.
Each dispatch zone has usually has ONE frequency, with many "Remote Bases".
A dispatcher can activate each remote base on or off as they choose, or simultaneously turn on groups of remote bases.
It is just much more convenient for dispatchers to leave ALL the remote bases in their zone activated.
That way if ALL the remote bases are activated, they don't have to spend time figuring out which remote base services an area that a train that is calling them is in.
So what this means to you is that you may clearly hear a dispatcher on the remote basenear you talking to trains hundreds of miles away via another remote base, while the train the dispatcher is talking to is far out of range of your hearing.
Also most RRs have separate Dispatch and Road channels.
This roughly compares to the Dispatch and TAC channels in public safety systems.
Dispatch channels are just that: dispatch giving orders, and co-ordinating trains on the mainlines.
Road Channels are used for communications within trains.
Remember that the end of a train may be as much as a 4000 feet from the locomotive.
During switching, the brakeman at the far end of the train does NOT need to talk to Dispatch.
He does need to tell the engineer:
1)to stop when the switch is passed by the end of the train,
2)when it is ok to start backing into the siding after the switch is thrown,
3) when to stop when the car is in its final resting position
4) car is uncoupled, move out of the siding,
5) stop, the train is back on the mainline we are clear of the siding, let me reline the switch
6) Highball! the switch is relined to the main.
Listening to Dispatch channels will give you an idea of how traffic is flowng on an entire RR division.
Listening to Road channels, when you can hear them, will give you an idea about what activity is going on near you.
Also listen to EOT and FRED channels, because of their comparatively low power, you will only hear them when a train is very close to you.
