PL Tones and how does the dispatcher hear trains?

[ofd8001]

I'm relatively new to railroad monitoring.

Do railroads use PL tones?

How do dispatchers a long way off hear trains if they are on a simplex channel?

Thanks!!

 

[icom1020]

some shortlines that have repeaters use sub-audible or 'pl' tones but most others do not. Towers to communicate from train to dispatcher are brought up through DTMF selective tones.

A dispatcher can monitor or call up trains from dispatch centers like Ft Worth or Omaha via microwave links.

 

[Grog]

Here is the Norfolk-Southern Railroad microwave relay tower on Crowders Mountain 35 miles west of Charlotte NC

 

[icom1020]

I should also mention that fiber optics play a role in this too.

 

[W4KRR]

They have base station antennas set up, usually around every 15 to 25 miles along the tracks, so that trains and mobile units are never very far away from any receiving/transmitting station. The antennas may be set on wooden poles, on towers, on tall buildings, mountain tops, etc. The antennas are usually, but not always, located along or near the tracks, and usually, but not always, located on railroad property. The dispacther can select which of these antennas he uses to communicate with the trains, obviously he will choose the one that is closest to wherever the train is located. The communications from the train are sent to the dispatcher's location going through the closest base antenna, then the signal is routed either over leased telephone lines or microwave links to the dispatcher's location.

 

[karldotcom]

There is a good book called Railroad Radio that discusses all these technologies....although now the RRs are getting into VoiP and other new technologies.