Defect Detectors

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thomast77

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Are they still in use? I recently started getting into Rail. I found some info that is dated showing Defect Detectors around 3-5 miles from me. I have never heard it. The Dispatch channel booms in here full scale.
 

ratboy

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I hear them constantly at home, both on NS and CSX on the main road channels. The NS ones (I can hear 2 of them all the time at home) are pretty weak, but one of the CSX detectors is quite strong, there's another one I can barely hear, unless the band opens up.. I don't know where it's at, but at a friend's house in Michigan it is very strong, so I'm guessing it's just over the border into Mich..
 

AK9R

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Defect detectors typically transmit on the "road" frequency for the particular line where the DD is located. In other words, the DD transmits on the frequency that the train crew is supposed to be monitoring as they are traversing the line. Defect detectors are usually low powered and use low profile antennas. Different railroads have different standards for their defect detectors. Some make an announcement when the train first crosses the DD so the crew knows its working. Most make an announcement after the train has cleared the DD even if their are no defects so the crew knows the DD has scanned the entire train. Most defect detectors announce their location by name or mile post number. Some DDs announce train length, number of axles, train speed, outdoor air temperature.

Depending on the type of defect detector, it will be looking for "hot boxes" (hot axle bearings), dragging equipment, high cars, hot wheels (often caused by sticking brakes), etc.
 

5kw

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Defect Detection Monitoring

For those that don't hear the "Detector" but do hear the dispatcher means the site is set for "Talk On Defect Only". When the site does talk usually means a hot bearing or wheel, dragging equipment, high/wide load alarm, in a perfect world you will never here the site talk unless it is being tested.

But, as a previous reply said, these locations are designed to talk to the train, the dispatcher transmits from a higher antenna, more power, in order to reach more trains in the territory. Other "Detectors are set to talk all the time for a few reasons.

Other things to consider are hills, distance from "Detector" typical VHF propagation and your antenna, coax and radio setup.

I hope that helps.
 

thomast77

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I was going to update this thread sooner, But I have been busy. I finally put up a 20-176 aka AntennaCraft ST3. I can now hear the defect detector. In fact I have even heard other DD's during a recent band opening. I hear a great deal more than I did. Thank You all for your input.
Tom
 

Kitn1mcc

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Amtrak when they went narrow band turned down the power on most of the detectors.

Roads like metro north do not use talking detectors
 

5kw

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Defect Detection Voice

Detectors talk on the "Road Channel" of the track the train is on.

Data is not on the "Road Channel".
 

burner50

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Do most DD's talk on the road channel? Or is it data? I have never heard a DD before.

If a detector talks, it will be on the Road channel, so the crew can hear it and act immediately. The data will be on a different frequency, most likely ATCS, or wired network.

Many times, the office will see something on the detector readout that doesn't trip a defect detector.
 
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