Telemetry (HOTD, EOTD, DPU) different channels?

[NS9710]

I’m just wondering if now that a lot of things being changed (ATCS going onto PTC and being phased out of being separate setups), have the DPU and/or EOTD/HOTD been changed in frequency? I have the 452/457.9375, and the associated DPU 4 channel sets been changed?

I have noticed in some situations that I don’t hear the telemetry channels making their traditional beep and burping tones.

I’m using a Uniden BCD160DN with a Smiley Antenna 5/8 Slim Duc 160MHz antenna.

 

[wa8pyr]

I’m just wondering if now that a lot of things being changed (ATCS going onto PTC and being phased out of being separate setups), have the DPU and/or EOTD/HOTD been changed in frequency? I have the 452/457.9375, and the associated DPU 4 channel sets been changed?

I have noticed in some situations that I don’t hear the telemetry channels making their traditional beep and burping tones.

I’m using a Uniden BCD160DN with a Smiley Antenna 5/8 Slim Duc 160MHz antenna.

No, frequencies are still the same.

Using a VHF antenna will slightly decrease your reception of those frequencies to some extent.

 

[NS9710]

There have been some times which a train has rolled past me and I have not heard the first HOTD, EOTD, or DPU blip

No, frequencies are still the same.

Using a VHF antenna will slightly decrease your reception of those frequencies to some extent.

 

[wtp]

only thought i have is to set the squelch to 0(zero).

 

[wa8pyr]

There have been some times which a train has rolled past me and I have not heard the first HOTD, EOTD, or DPU blip

I get that occasionally as well. Just one of those things, I just don’t worry about it.

 

[AK9R]

I get that occasionally as well. Just one of those things, I just don’t worry about it.

I was under the impression that EOTDs only transmit when the speed or brake line pressure changes or when interrogated by the HOTD.

 

[RugbyJunctionWI]

I’m using a Uniden BCD160DN with a Smiley Antenna 5/8 Slim Duc 160MHz antenna.

Perhaps it's your antenna, tuned to the wrong frequency? About the only trains that evade my SDR scanner are lite power moves when there is no EOT or DPU, thus no HOT either.

 

[wa8pyr]

I was under the impression that EOTDs only transmit when the speed or brake line pressure changes or when interrogated by the HOTD.

I forget, but that may be right.

 

[RadioDitch]

I was under the impression that EOTDs only transmit when the speed or brake line pressure changes or when interrogated by the HOTD.

Correct. The older EOT's also transmitted at a default interval if neither of those events occurred.

I don't believe any of the Wabtec NG, DPS 2020-He, or Siemens AP EOT's still carry that programming though. Some of the older Wabtec ATX Air Turbine markers might since there's a bunch of those around, despite them being a monster pain in the backside. Mostly all units are operating at 8 watts now also.

Keep in mind an EOT is not required if there is a DPU on the end of the train as the DPU's reporting is permitted to function as an EOT.

 

[iceman977th]

The railroads have also been looking at moving EOT/DPU operations into the 220 band.. whether it's embedded into ITCnet (PTC) or just using the same frequencies for standard EOT/DPU comms we're not sure.. but I would guess a lot of that is moving into ITCnet as the technology advances.

Mike

 

[ComradeGlock]

Unfortunately the 220 band is pretty much out of bandwidth now. And current legacy EOT/HOT/DPU systems have real connectivity issues in dealing with very long trains and varying terrains.

If you want a peek at what is probably the future (I believe) of railroad comms, take a look at a company called Ondas. They have a relatively new wireless protocol IEEE 802.16t which has already been adopted by the AAR and are offering the railroads secure, reliable comms in predominantly the 900mhz band. If you go to their website Private Wireless Networks for Mission-Critical Operations | Ondas Networks and click on the "Applications" tab, you'll see the kinds of offerings that are available. Dig around on their site and you can really get lost in the breadth and complexity of what they're offering the railroads. A lot of info in their Press Releases and Articles pages too.

Secure, reliable, and redundant comms (data and voice) are all brought to the fore with this new(ish) protocol in the 900 band on their network.

(Full disclosure, I have absolutely no affiliation with Ondas, just a curious hobbyist.)

 

[RadioDitch]

Unfortunately the 220 band is pretty much out of bandwidth now. And current legacy EOT/HOT/DPU systems have real connectivity issues in dealing with very long trains and varying terrains.

If you want a peek at what is probably the future (I believe) of railroad comms, take a look at a company called Ondas. They have a relatively new wireless protocol IEEE 802.16t which has already been adopted by the AAR and are offering the railroads secure, reliable comms in predominantly the 900mhz band. If you go to their website Private Wireless Networks for Mission-Critical Operations | Ondas Networks and click on the "Applications" tab, you'll see the kinds of offerings that are available. Dig around on their site and you can really get lost in the breadth and complexity of what they're offering the railroads. A lot of info in their Press Releases and Articles pages too.

Secure, reliable, and redundant comms (data and voice) are all brought to the fore with this new(ish) protocol in the 900 band on their network.

(Full disclosure, I have absolutely no affiliation with Ondas, just a curious hobbyist.)

I doubt voice comms will ever change due to the issues that interop between carriers would present.

 

[iceman977th]

Unfortunately the 220 band is pretty much out of bandwidth now. And current legacy EOT/HOT/DPU systems have real connectivity issues in dealing with very long trains and varying terrains.

If you want a peek at what is probably the future (I believe) of railroad comms, take a look at a company called Ondas. They have a relatively new wireless protocol IEEE 802.16t which has already been adopted by the AAR and are offering the railroads secure, reliable comms in predominantly the 900mhz band. If you go to their website Private Wireless Networks for Mission-Critical Operations | Ondas Networks and click on the "Applications" tab, you'll see the kinds of offerings that are available. Dig around on their site and you can really get lost in the breadth and complexity of what they're offering the railroads. A lot of info in their Press Releases and Articles pages too.

Secure, reliable, and redundant comms (data and voice) are all brought to the fore with this new(ish) protocol in the 900 band on their network.

(Full disclosure, I have absolutely no affiliation with Ondas, just a curious hobbyist.)

I don't see how they're out of bandwith. I've sniffed around on SDR's to see what frequencies are in use and there's maybe 10-12 in use max, at least here. I'm pretty sure they have the entire 217-222MHz spectrum to do with as they please.

I've seen that in papers before but never found any actual offerings. 900 is going to be a challenge for most railroads though, it would either have to replace VHF comms or be integrated into ITCnet somehow.

I doubt voice comms will ever change due to the issues that interop between carriers would present.

That won't matter. They'll either dual-install or force change and tell other railroads to deal with it. Just like everything else.

 

[NS9710]

I was aware of the DP if placed on the rear being a suitable replacement for an EOT, although I have seen a rear EOT and Rear DP both be used in years past.

Correct. The older EOT's also transmitted at a default interval if neither of those events occurred.

I don't believe any of the Wabtec NG, DPS 2020-He, or Siemens AP EOT's still carry that programming though. Some of the older Wabtec ATX Air Turbine markers might since there's a bunch of those around, despite them being a monster pain in the backside. Mostly all units are operating at 8 watts now also.

Keep in mind an EOT is not required if there is a DPU on the end of the train as the DPU's reporting is permitted to function as an EOT.

 

[ecps92]

IMHO
Also keep in mind, many of the (new and old) Digital (P25 etc) scanners have a slower "attack" time for reception of Analog Signals.

I know in my travels, many of the FAA/NWS Telemetry at the airports it is almost impossible to search and find unless I manually step thru those.... you might be best to find an older Analog handheld for this purpose

 

[RadioDitch]

IMHO
Also keep in mind, many of the (new and old) Digital (P25 etc) scanners have a slower "attack" time for reception of Analog Signals.

I know in my travels, many of the FAA/NWS Telemetry at the airports it is almost impossible to search and find unless I manually step thru those.... you might be best to find an older Analog handheld for this purpose

True. Definitely need to make fine adjustments to the programming and settings. One of the reasons many of us hams prefer to use our amateur radio or commercial gear at trackside.

 

[ComradeGlock]

The 220mhz band works for current PTC requirements (except primarily the Chicago area) but doesn't come close to meeting the data transfer bandwidth demands that railroads are facing to improve safety and comms reliability. The railroads are already in the new 900mhz private wireless networks as forced in part by the FCC licensing for that band utilizing the IEEE 802.16t protocol. EOT/HOT/DPU will most likely be the first to utilize the newly licensed band because that process has real on the ground issues now that need to be addressed and the equipment and network already exists for it.

Ex: BNSF stays silent as rail industry faces pressure to meet FCC’s 2025 deadline

Read the documentation on the studies distributed by the FRA and AAR regarding the types of comm's they're researching. You'll find they generally point to a cab mounted SDR with 220, 900, and LTE radios (with the potential for others). Significantly simplifies the comm hardware and roof mounted furniture.

If someone told you 10 years ago that the RR's would be able to scan an entire train moving at track speed with 1,000 pictures per second of potential failure points, scan those pics utilizing AI, send any suspicious findings to a human, and that human has the ability to stop the train with literally a push of a button all with seconds, you'd have looked at them like they were crazy (I suspect similar to the way some of you are looking at this post right now). But it's happening now, multiple times a day from multiple sources across multiple Class 1's. (That's a LOT of data being moved, processed and stored.)

I know the Class 1's have traditionally been reluctant to change. But when one derailment due to a lack of proactive and/or infrequent critical failure point monitoring can cost over $1 Billion, that tends to put a little giddy up in management's step.

 

[RadioDitch]

If someone told you 10 years ago that the RR's would be able to scan an entire train moving at track speed with 1,000 pictures per second of potential failure points, scan those pics utilizing AI, send any suspicious findings to a human, and that human has the ability to stop the train with literally a push of a button all with seconds, you'd have looked at them like they were crazy (I suspect similar to the way some of you are looking at this post right now)..

Very valid and fair point. You are right. Change and advance is inevitable by some measure.

Honestly, I was never interested in ATCS or anything like that, so the switch to ITC/PTC, and many routes going CSS without intermediates didn't mean anything to me. I've always been a go somewhere interesting, turn on the radio, and see what happens type of railfan. But if voice comms on the high iron do ever go unmonitorable, that'll be it for me in the railroad hobby. As interested as I am in the railroads and railroading, it's always been combining my big interests that has allowed me to enjoy myself trackside.

Guess I'll just have more time for DX trips, satellite roves, and scanning...

 

[RugbyJunctionWI]

TL;DR... When scanning, it's entirely possible for simultaneously transmitted telemetry signals to compete with each other and thus get missed.

I recently started experimenting with the AirSpy SDR# software's "slicer" functionality with an AirSpy Mini software defined radio (SDR) and SoftEOT/SoftDPU to decode the telemetry signals, and now I see just how many train telemetry signals a scanner actually misses. With scanning, telemetry signals can "step on each other", resulting in missed signals. I.e., if a train has one or more DPUs and a FRED, it's likely that both the FRED and the DPUs are sending signals to the locomotive at the same time. With scanning, the radio will lock onto whichever signal it "hears" first but then completely miss any other signals that were sent at the same time.

With slicing, this issue of "stepping on each other" doesn't exist. The SDR is listening to all 6 telemetry frequencies at the same time and in different threads, so if there is an EOT signal at the same time as a few DPU signals, the SDR catches them all. Obviously, this is only something that one can do with an software defined radio and not a hardware scanner (at least no hardware scanner I'm aware of). Even with a fast hardware scanner, it's still likely something will be missed.

 

[ComradeGlock]

@RadioDitch - I completely agree. With nothing to listen to (eventually) and every loco looking the same, railroads just become another way to get your Amazon package the next day.

Everything I've read from FRA, AAR to vendors, the Class 1's at least are starting to see themselves as Tech companies, only running diesel engines instead of search engines.