Head of Train Data Bursts

N4IFE

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I live along the SE coast of Florida near the FEC road. I frequently hear what sounds like short bursts of data on the frequency designated as the “Head of Train” device (452.9375). Is there any software available to use with a SDR to decode the data burst?
 

N4IFE

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Thanks. Does not appear anything sufficiently interesting in the data to justify the effort.
 

chrismol1

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Yea it's another way to find out if there is equipment in the area, it works good for that. The EOT will tell you if there is movement or not in the data stream, and with brake pipe pressure and EOT unit number you can get an idea of whats moving in the area and how many , and obviously the stronger the signal the closer the action and the HOT being on top the locomotive will give a stronger signal earlier
 
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burner50

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The only thing you'll hear from HOT is a few commands during arming and emergency brake applications.

EOT broadcasts telemetry which is only marginally more interesting.
 

Tim-B

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I monitor the HOTD frequency often but just to alert me that a train is approaching. I can usually start receiving the data burst about 5 minutes or so before the train actually shows up. That is good in areas where you are between yards and there isn't much voice traffic on the radio from the train because he is just cruising along enroute. I turn that volume up to get my attention and when I hear a loud squawk then I know.
 

chrismol1

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The only thing you'll hear from HOT is a few commands during arming and emergency brake applications.

EOT broadcasts telemetry which is only marginally more interesting.
Was there an increase in power of EOTs considering the longer trains these days? I remember something like starting at 4, then nowadays its 8 or 10 watts now??

Also, if there is a mid train DPU I've heard maybe there's EOT repeaters from the DPU to send that to the HOT receiver or something like that new these days? Also, how many watts do the DPUs put out? I suppose less considering the antennas are on top the locomotives ??
 

burner50

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IF there is an EOT on the rear, and that's a pretty big IF, there would likely be a mid-train repeater.

But the majority of the time there is no EOT on the rear when there is a DPU, so there's nothing to listen for.
 

chrismol1

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IF there is an EOT on the rear, and that's a pretty big IF, there would likely be a mid-train repeater.

But the majority of the time there is no EOT on the rear when there is a DPU, so there's nothing to listen for.
Oh yea I forgot to distinguish between mid train DPUs vs end of train DPUs. So the locomotives have a program to be EOT's if they are run as end of train DPUs so therefore the EOT would be using the DPU's antenna for EOT transmissions

So the EOT number would be the number of the DPU? If the end of train DPU is the same unit as the EOT except with additional EOT payloads would be attached to the DPU payload packets right because it would be broadcasting not only its power fields but also the brake pressure so this would all feed into the same central computer. I'm not 100% familiar so please correct me

So if a train was using a DPU as end of train there would be no EOT transmissions on the usual EOT frequencies? And if it was a mid train DPU the EOT would be broadcast along with the DPU freqs so thats 2 freq data transmissions among the unit. so That would be how you'd distinguish if a train was rear DPU or not by the lack of EOT freq transmissions as its included with rear DPU tranmissions?
 
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AK9R

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I made the Azz-umption that we were talking about mid-train DPUs. Of course, if it's an end-of-train DPU, no marker is needed.
 
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