Head of Train Data Bursts

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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.
 

KC2CQD

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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?
I've always enjoyed ATCSMonitor.
You could join the group, download the software and Virtual Pipe the audio from your SDR into it and select that as a source after getting the DL for FECs system. you'll even get a Dispatcher Layout. The DLs for various systems DO have server connections too if someone is streaming it.
 

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burner50

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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?


They don't act as an EOT. An End Of Train Device serves a specific purpose. A DPU serves some overlapping functions, but covers far more than what an EOT would do. If there is a rear DPU, there is no EOT unless there is an EOT deadheading for some reason. So, once you realize that they're completely separate things, you'll have an easier time understanding.

Not all circumstances dictate the use of an EOT, and their use is declining. There needs to be a marker on the rear so that other trains can verify that the train they're meeting is complete and intact. An EOT is a common modern way to accomplish this, but it can also be accomplished with a lantern, a person riding the rear, a DPU, a fusee, etc... Something to indicate that the train is complete and there isn't random cars left somewhere on the main line.

As far as what is contained in the data for a DPU, there is all sorts of things. A DPU can be operated almost completely as any other engine independent of the lead engines by radio control. As far as how to determine which you're hearing I can't say that I have ever tried to monitor DPU data. It's been several years since I left the railroad, but I believe DPU data is also on UHF.

The most surefire way to determine if there is an EOT vs a DPU is to look at the rear end.
 

wa8pyr

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Not all circumstances dictate the use of an EOT, and their use is declining. There needs to be a marker on the rear so that other trains can verify that the train they're meeting is complete and intact. An EOT is a common modern way to accomplish this, but it can also be accomplished with a lantern, a person riding the rear, a DPU, a fusee, etc... Something to indicate that the train is complete and there isn't random cars left somewhere on the main line.

I would disagree with use of EOTs declining. Virtually every train I see has one, unless it's got a rear DPU, or is a short local doing a lot of enroute switching, in which case it's simply got a flag stuck in the coupler hole (that's not common around here; even the locals usually have an EOT).
 

burner50

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I would disagree with use of EOTs declining. Virtually every train I see has one, unless it's got a rear DPU, or is a short local doing a lot of enroute switching, in which case it's simply got a flag stuck in the coupler hole (that's not common around here; even the locals usually have an EOT).

I said declining... Not rare.

Class 1's are figuring out they can run longer trains with DPU's using less fuel and less crews, so they're using DPU's on as much as they can.

When I started with Union Pacific in 2006, the only trains that had DPU were loaded coal trains. A monster manifest was 5,000 feet. Coal trains were the longest thing out there at 7,500 feet.

Now, they're running manifest trains over 10,000 feet routinely. Stackers are pushing 15,000 feet. The limiting factor wasn't a lack of power... It was most often drawbar forces. DPU can eliminate high drawbar forces, so they're using them as much as possible.

There's certain rules that make running with just a flag difficult. First, they can't run after dark. Second, after the brake pipe is broken to add or remove cars, someone has to physically walk to the rear with a gauge to ensure air is making it all the way to the rear. Third there's weight and speed limits on trains that do not have the capability of initiating an emergency brake application from the rear.
 

AK9R

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I think EOT use may vary around the country depending on the operating practices in those regions. If you are observing trains in an area where putting distributed power on the rear of the train is common, then it would be easy to conclude that use of EOTs is declining.

For a long time, the CSX trains I saw in central Indiana only had power on the head end and an EOT on the rear end. Then, they started using mid-train DPUs. That practice still required an EOT on the rear end. Some of the trains in and out of Avon Yard have mid-train DPUs. Some just have power on the head end. Since @wa8pyr lives just one state east of me, his experiences may be similar to mine.
 

cr8054

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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.
Monitoring the telemetry devices is ok out on the road, but can be a nuisance if you are close to a yard and there are multiple telemetry devices pinging away in the yard some of which are just laying on the ground pinging until the battery dies.
 

AK9R

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I live near CSX Avon Yard which is a large hump yard on the main route between Cleveland and St. Louis. I made the mistake of putting the HOT frequency in a scanner. For the most part, all I heard were HOTs since there are so many locomotives around the yard. I locked out the HOT frequency, but I've left the EOT frequency in the scan list. It's not much of a problem unless I'm on the periphery of the yard.

In my experience watching trains at Avon Yard, the car inspectors grab the EOT off of inbound trains as they inspect the trains in the receiving yard. They may switch off the EOTs at that point. The EOTs travel in the back of a car inspector's pick up truck to a small shop near the departure yard where they are serviced and tested. After that, the EOTs hang on a rack outside the shop. The car inspectors then hang the EOTs onto outbound trains in the departure yard.
 

Tim-B

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Monitoring the telemetry devices is ok out on the road, but can be a nuisance if you are close to a yard and there are multiple telemetry devices pinging away in the yard some of which are just laying on the ground pinging until the battery dies.
Yeah, you're right. I learned that real fast. BNSF operates a yard a couple of miles from where I live and they use the big road locomotives for yard jobs instead of using smaller switching units. So there are multiple HOTDs going off one right after the other. I usually don't start monitoring the HOTD frequency until I am at least 5 miles or more away from the yard and on my way to any one of several observation spots I use that are in rural areas or small towns. I like these spots cause I get to see em pass faaaast.
 
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