dic
Member
Listening to the Lancaster/Tehachapi feed on railroad radio.net and am hearing DTMF (phone) tones.
What purpose do they serve?
Thank you
Dic
N1XBA
What purpose do they serve?
Thank you
Dic
N1XBA
(never heard of them activating crossing circuits).
Dick Samuels, owner and operator of the Oregon Pacific Railroad, explains that here for his specific shortline:
Altamont Press Discussion Board :: Discussion :: Re: Oregon Pacific Railroad's GMD-1 in Snow Action - Video link
At about 24:29 in the video they are discussing, you can see the sticky that shows the specific tones for each street (only two, in this case).
https://www.youtube.com/watch?v=ro8u61gF2SI#t=1469
Also used to have detectors repeat transmissions. Not sure what number they key in but on many installs on CSX, the detector will respond "Rebroadcast" and then repeat the last transmission.
Back in the day railroads used to use PBX (Private Branch Exchange). Basically it was a phone-to-radio-to-phone interface where a special code is dialed to access the PBX, and then the phone number is dialed all using DTMF tones. CSX used to use it to call signal maintainers, yard masters, ect.
Listening to the Lancaster/Tehachapi feed on railroad radio.net and am hearing DTMF (phone) tones.
What purpose do they serve?
Thank you
Dic
N1XBA
The three digit DTMF tones are in fact used to light a light and sound a tone in the dispatcher's pod at the Harriman Center (or BNSF's dispatch center in Tx) to let them know somebody needs to talk to them.
They don't normally listen to all the chatter that goes on and for good reason:
So the solution is: each Base station has a DTMF tone decoder that has a unique code to trigger it. The train crews know what that code is.
The train crews can also send a different set of DTMF tones to a detector and have it play back the details of the last test. This is so they can confirm what they think they heard..