Do any RR's use tone squelch?

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Do any RR's use tone squelch?

Postby CPSK » Thu Jun 25, 2009 9:25 pm

I am wondering whether any RR's use CTCSS (not DTMF) tone squelching. This would prevent unwanted transmissions from other services from opening the squelch on the receiver.
I am particularly interested in this because my radio is capable of using tone squelch (it is actually amateur equipment), and it is used all the time on amateur bands, and police bands.
It would make RR monitoring a lot easier, since I am receiving a lot of IMD (intermod) on my radio. If tone squelch was engaged, I would not hear these offending signals because the tone would not be present.

I have looked at various RR radio frequency websites, and none mention CTCSS tones.
I can set my radio to scan for them, but with RR transmissions being so infrequent and short, it is nearly impossible to lock in on any tones.


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Re: Do any RR's use tone squelch?

Postby litz » Fri Sep 11, 2009 2:13 pm

Most railroads don't bother. LMR radios are highly restricted and regulated, and the chances of someone unwanted broadcasting on your AAR channel is pretty remote. Not to mention highly illegal.

Only one does, that I know of, locally ... they use a commercial business channel for a passenger subsidiary, and there were issues in the past with the local McDonald's drive thru (kid you not) and they enabled a tone squelch to block out the McD's transmissions (McD's, for their part, eventually went hard wired) ... and when they set the tone squelch on the subsidiary's business channel, they set the same on their primary AAR frequency as well.

McD's no longer transmits, so the issue is no longer there, but to undo it would require reprogramming all their radios; probably won't happen until the narrowband radios are purchased (whenver that happens). As is usual for a railroad, since what they've got works, why change it?

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