Railroad Defect Detection - 457.9125

Discussion forum for scanning Eastern Massachusetts, including Norfolk, Suffolk, Middlesex, and Essex counties, as well as the greater Boston metropolitan area.
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ecps92
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Railroad Defect Detection - 457.9125

#1 Post by ecps92 » 01 Sep 2019 15:20

Nothing in the Wiki for Eastern/Southeastern Mass

But recently began hearing 457.9125 CSQ with varying signal strengths, indicating different distances, sending a DTMF code [have not enabled my old CD-1]
http://www.connectsystems.com/support/manuals/CD1.pdf

Wondering if anyone else can validate this for one of our Local Railroads.
The FCC only shows Providence and Worcester, but I am in Weymouth

time to see if these coincide with the Purple Line
https://sites.harvard.edu/~wuensch/T/co ... l-map.html
Bill Dunn N1KUG
Cruise Ship Frequencies
http://scanmaritime.com

"The tougher it is to find a frequency, the more it makes me want to work to find it. - I've learned to use the SEARCH Button"

T405
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Joined: 30 Aug 2019 15:31

Re: Railroad Defect Detection - 457.9125

#2 Post by T405 » 01 Sep 2019 20:04

I think its an alternate telemetry frequency for EOT devices. Usually they run 457.9375 but I believe the newer ones have a multi channel set up in case of interference(like the old 49meg cordless phone)

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schwab
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Re: Railroad Defect Detection - 457.9125

#3 Post by schwab » 01 Sep 2019 23:15

457.9375 isn't defect detection, it's brake pipe pressure telemetry send from the rear of the train to the head end. 452.9375 is head to tail telemetry. This data is sent via packet bursts, not DTMF. Co-channel interference wouldn't be a problem, since each packet burst has the marker/receiver number encoded.
Jacob
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ecps92
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Re: Railroad Defect Detection ?? - 457.9125

#4 Post by ecps92 » 02 Sep 2019 11:27

Since the only licenses, I found and references were Railroad and Defect, hence the Subject line,

However this is 100% DTMF and only fairly [within the last week] NEW, as I scan 457/467 regularly from the QTH for Maritime Activity
And so far this AM [Monday] despite Commuter Rail Traffic, nothing has been heard......
schwab wrote:
01 Sep 2019 23:15
457.9375 isn't defect detection, it's brake pipe pressure telemetry send from the rear of the train to the head end. 452.9375 is head to tail telemetry. This data is sent via packet bursts, not DTMF. Co-channel interference wouldn't be a problem, since each packet burst has the marker/receiver number encoded.
Bill Dunn N1KUG
Cruise Ship Frequencies
http://scanmaritime.com

"The tougher it is to find a frequency, the more it makes me want to work to find it. - I've learned to use the SEARCH Button"

wltrsf
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Joined: 29 Aug 2005 19:28
Location: Rt 495@ Rt2

Re: Railroad Defect Detection - 457.9125

#5 Post by wltrsf » 02 Sep 2019 19:37

The original post is about 457.9125 not 457.9375. 457.9375 and 452.9375 are indeed EOT frequencies for railroads across the country. Don't know about 457.9125, could be PTC related.

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