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Rolling CTCSS

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Astrak

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I have been listening to a business on my scanner recently and the CT tone continuosly changes when they are talking, is this normal or is the scanner not receiving properly?
 

DaveH

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How often is the code changing, and what type of receiver are you
using? The PRO-92 has been known to flip around a bit in its
decoding. Are you sure this isn't a multi-user channel?

I've never seen a system that uses rolling CTCSS, except
possibly a very early (1980's) 1st-generation trunking that used
CTCSS in a non-conventional way (Ferritronics; company is long
defunct).

I've seen LTR falsely trigger a CTCSS decoder (certain data
patterns match certain tones). Also, certain LTR patterns have been
known to interefere with certain DCS codes on the same channel.

Dave
 

Astrak

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I'm using the PRO-97 and listening to the railroad and the CTCSS constantly changes while listening to one person talk. This is in CT search mode.
 

KCChiefs9690

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I have the PRO-2055, and that happens sometimes to me too. I heard someone tell me to go with the code that shows up the most. How far away from the station are you? A possibility is that if you are far away, it could pick up false codes.
 

rattlerbb01

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I'm not much of a railfan at all, however, don't railroads generally not use CTCSS or DCS on their channels? Everything down here in Texas is toneless on the 160-161 mhz channels. Railyards and loading companies might use it for local repeaters but not any of the line channels down here.
 

jmp883

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Astrak wrote:

I'm using the PRO-97 and listening to the railroad and the CTCSS constantly changes while listening to one person talk. This is in CT search mode.
You've just answered your own question :D ! Take the radio out of CT Search and you won't see that anymore. I can't speak specifically for the PRO-97 but most scanners operate the same way.....when you have the radio in CT Search it will constantly scroll through the CTCSS tones until it finds the one that the user you're listening to is using. The scanner will then stop on that CTCSS frequency, usually flashing it until you enter it into the radio memory.

Now here's a railroad radio tip.....I'm a railbuff/modeler as well as a radio buff and in all my years of listening to railroads from the midwest to the east coast I've yet to find one that uses either CTCSS or DPL. Their PD's or M-O-W units may use CTCSS or DPL but the trains themselves use CSQ-Carrier Squelch. Just program the frequency, set the squelch to just where the white noise disappears, and listen away! :D
 

wa8pyr

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Astrak said:
I'm using the PRO-97 and listening to the railroad and the CTCSS constantly changes while listening to one person talk. This is in CT search mode.
Your radio is probably picking up tone artifacts from the speaker's voice; this happens often, and is especially common with DTMF decoders. I see both regularly.

Tom WA8PYR
 

Astrak

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jmp883 said:
Astrak wrote:



You've just answered your own question :D ! Take the radio out of CT Search and you won't see that anymore. I can't speak specifically for the PRO-97 but most scanners operate the same way.....when you have the radio in CT Search it will constantly scroll through the CTCSS tones until it finds the one that the user you're listening to is using. The scanner will then stop on that CTCSS frequency, usually flashing it until you enter it into the radio memory.

Now here's a railroad radio tip.....I'm a railbuff/modeler as well as a radio buff and in all my years of listening to railroads from the midwest to the east coast I've yet to find one that uses either CTCSS or DPL. Their PD's or M-O-W units may use CTCSS or DPL but the trains themselves use CSQ-Carrier Squelch. Just program the frequency, set the squelch to just where the white noise disappears, and listen away! :D
Normally the PRO-97 will not display a tone until it picks it up in search mode, it doesn't scroll through them. So how does the rail radio work, I hear them call Omaha which I suspect means Omaha Nebraska so does that mean the radio is sent over phone line or something.
 

jmp883

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Astrak wrote:

Normally the PRO-97 will not display a tone until it picks it up in search mode, it doesn't scroll through them.
Maybe you're a little confused, or maybe I'm a little confused here.....:wink:

Like I said before I'm not familiar with the PRO-97 but in your original post you said that the CTCSS constantly changes while you're listening to a transmission and that the radio is in the CT search mode. If you can see the CTCSS tone constantly changing, and you know the radio is in the CTCSS search mode then one way to describe what you're seeing on the radio display could be called scrolling.

Anyway, to answer your railroad radio question.......rail radio works just the same as any other basic two-way radio system. I dispatched for a large northeastern commuter railroad. My territory consisted of 90 miles of double-track railroad hosting both our commuter trains and freight trains of a major freight railroad. We used one frequency for the entire territory and selected the repeater/antenna sites based on where the train was we needed to talk to. In the field the engineer or conductor would key up and the signal was automatically picked up by the nearest repeater/antenna. This allowed us to talk to multiple trains, on the same frequency, at the same time, without interfering with anyone else on the same frequency. In my opinion this was not the best arrangement since there were several territories that all used this same frequency. The southern half of the the state had a different frequency, but it was the same method.

I have family in Omaha, NE and I've listened to both the UP and the BNSF railroads when I'm visiting. I've heard those same tones before and after transmissions and after talking to other train dispatchers, radio people, and rail buffs I've found out that those tones are either DTMF (Dual Tone Multi-Frequency) or PBX (Private Branch Exchange) tones. These tones are used to activate specific repeater/antenna sites. Again, this allows trains on the same frequency to talk to different dispatchers without interfering with each other. It works much the same as CTCSS or DPL, the only difference, from a scanner standpoint, is that all you need to do is program the radio frequency in and listen.

Hope this helps......and of course if anyone can correct/update my information I'd be more than grateful! :D
 

W4KRR

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I don't believe the PRO-97 scrolls through the tones when it's in tone search mode. The display simply remains blank until it receives the proper tone, and then it's displayed.

Very often when monitoring a frequency that doesn't use a tone, a tone might briefly appear, sometimes alternating with other tones. As someone above said, it's picking up artifacts from the voice and not an actual PL tone.
 

EricCottrell

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jmp883 said:
Astrak wrote:
Now here's a railroad radio tip.....I'm a railbuff/modeler as well as a radio buff and in all my years of listening to railroads from the midwest to the east coast I've yet to find one that uses either CTCSS or DPL. Their PD's or M-O-W units may use CTCSS or DPL but the trains themselves use CSQ-Carrier Squelch. Just program the frequency, set the squelch to just where the white noise disappears, and listen away! :D
Hello,

In the Boston area some of the railroad dispatchers (base stations) do transmit a PL tone but the trains do not. The PLs are not all the same. I use carrier squelch so I do not miss the train side.

I am taking a train trip soon out to New Mexico. I like listening to the road channel on the scanner as I travel. My first time through Chicago by rail.

73 Eric
 

DaveNF2G

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On the old Conrail mains in the northeast, the trackside detector announcement transmitters used a 100.0 Hz tone, but CSX is replacing that equipment and the tone is going away.
 
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