Malfunctioning EOTD/HOTD for days?

Joined
Feb 15, 2021
Messages
39
Location
City, State
Hi railroad/railfan monitoring enthusiasts, good morning.

For about the last five days, my radios have been stuck on the EOTD/HOTD freqs due to constant transmissions that individually sound like normal transmissions.

But these have different cadence (I guess you'd call it) from the normal of about 2-4 seconds between squelch release and following squelch break.

These are repeated transmissions with virtually no break between and in sort of a 1-2-3 rest, 1-2-3 rest, etc. as if some joker swiped a device of a train and is manually triggering the transmission to the rhythm of Jingle Bells or other simple rhythm.

The tracks are about a mile away and RR operations seem to be about normal, other than these odd transmissions.

I was considering contacting the RR emergency line to report it but frankly I would feel like a dope reporting something like this as an emergency.

Thoughts?
 
Last edited:

alabamarailfan

Member
Premium Subscriber
Joined
Jan 6, 2009
Messages
221
Not sure if it would help diagnose what is actually going on but there is software that will decode the EOT/HOT data packets:

Are you getting this data on the HOT (452.9375 MHz) or the EOT (457.9375 MHz) frequency or both?
 
Joined
Feb 15, 2021
Messages
39
Location
City, State
Not sure if it would help diagnose what is actually going on but there is software that will decode the EOT/HOT data packets:

Are you getting this data on the HOT (452.9375 MHz) or the EOT (457.9375 MHz) frequency or both?
Hi, thanks for responding.

The sounds are heard on HOTD and EOTD freqs at the same time.

Some other things about it...

The bc125at squelch set at 2 breaks on the frequencies fairly steadily while the sds100 squelch must be turned all the way to zero to even barely hear it.

I stood by a crossing while a train rolled by and I heard the "real" HOTD punctuated by the cadenced sound, which was when I realized the cadenced sound AKA fake sounds similar to but not the same as the "real".

Also, once the train left the area, I couldn't hear the real anymore.

Lastly, at a point about 2 to 2.5 miles away, I can still hear the fake but not the real.

Thanks for your help.
 
Joined
Feb 15, 2021
Messages
39
Location
City, State
Not sure if it would help diagnose what is actually going on but there is software that will decode the EOT/HOT data packets:

Are you getting this data on the HOT (452.9375 MHz) or the EOT (457.9375 MHz) frequency or both?
That would be both at the same time.



Thanks for your response
 
Last edited by a moderator:
Joined
Feb 15, 2021
Messages
39
Location
City, State
What if there is a train with an EOTD that is rolling along communicating just fine with the lead power...

Then the lead power enters an area in which a bogus signal (which is also more powerful than the bona fide signal) is being transmitted more or less randomly...

Effectively jamming the channels for as long as the bogus signal is stronger than the bona fide...

What would happen? Anything bad to the train operation?

I seem to recall an accident occurred decades ago in California when the EOTD failed a certain number of times to communicate with the lead, it gave up and never retried.

But I think that's been fixed.
 

KB1VLA

Member
Joined
Nov 22, 2012
Messages
320
Location
South Berwick, ME
What if there is a train with an EOTD that is rolling along communicating just fine with the lead power...

Then the lead power enters an area in which a bogus signal (which is also more powerful than the bona fide signal) is being transmitted more or less randomly...

Effectively jamming the channels for as long as the bogus signal is stronger than the bona fide...

What would happen? Anything bad to the train operation?

I seem to recall an accident occurred decades ago in California when the EOTD failed a certain number of times to communicate with the lead, it gave up and never retried.

But I think that's been fixed.
The head end box on the locomotive is paired with a specific EOTD by its marker number. The head end box will ignore any other signal on the frequency unless is is from the specific marker it is paired with. They are paired with each other when a train does its terminal brake test.
 
Joined
Feb 15, 2021
Messages
39
Location
City, State
I posted two three videos to YouTube.

The first on is the sound of the rogue/bogus transmissions on the {EH}OTD frequencies being received in my living room, ignore the dispatcher voices, that sound is from the nearby SDS100 scanning the local metro network :


These sound like they're bursting too often and the bursts are cut off at the end.

In my opinion, the squawk sound doesn't sound like normal {HE}OTD transmissions such as these,


Then here is a 6:33 train roll-by video at the crossing about 1.5 miles from my living room.

I listened to the whole thing and heard no {EH}OTD squawking at all during the whole thing.

Normally once I see the headlights, I hear squawking, but not in this video for some reason:

 
Joined
Feb 15, 2021
Messages
39
Location
City, State
I posted two unlisted videos to amfriend's YouTube channel.

The first on is the sound of the rogue/bogus transmissions on the {EH}OTD frequencies being received in my living room, ignore the dispatcher voices, that sound is from the nearby SDS100 scanning the local metro network : 20221120 103110

In my opinion, the squawk sound doesn't sound like normal {HE}OTD transmissions.

The second is a 6:33 video with train roll-by at the crossing about 1.5 miles from my living room and I don't hear any {EH}OTD squawking during the whole thing. Normally once I see the headlights, I hear squawking, but not in this video for some reason:

And then lastly, here's a video from
The head end box on the locomotive is paired with a specific EOTD by its marker number. The head end box will ignore any other signal on the frequency unless is is from the specific marker it is paired with. They are paired with each other when a train does its terminal brake test.
Hi Thanks for your reply.

What if the locomotive and EOTD are paired and communicating fine.

Then the locomotive enters an area which has bogus transmissions at possibly a higher radiated power that would jam the legitimate communications.

Of course the head end would ignore the bogus transmissions but what if the EOTD is completely jammed for a while?

Would the condition be monitored and alerted upon by the locomotive safety systems if the head end fails to receive an intelligible transmission from the EOTD for let's say several minutes?
 

KB1VLA

Member
Joined
Nov 22, 2012
Messages
320
Location
South Berwick, ME
I posted two three videos to YouTube.

The first on is the sound of the rogue/bogus transmissions on the {EH}OTD frequencies being received in my living room, ignore the dispatcher voices, that sound is from the nearby SDS100 scanning the local metro network :


These sound like they're bursting too often and the bursts are cut off at the end.

In my opinion, the squawk sound doesn't sound like normal {HE}OTD transmissions such as these,


Then here is a 6:33 train roll-by video at the crossing about 1.5 miles from my living room.

I listened to the whole thing and heard no {EH}OTD squawking at all during the whole thing.

Normally once I see the headlights, I hear squawking, but not in this video for some reason:

That telemetry behavior doesn't seem all that abnormal to me. Sometimes the EOTD will send more than one packet burst at a time, depending on the data being sent, but it's totally normal. Usually whenever there is a brake pipe pressure change the marker will report that over the air to the head end box, so if/when a train goes into emergency (air pressure drops to 0) the marker will send an almost-continuous stream of data which sounds like the behavior you're describing; but again, that's totally normal.
 
Joined
Feb 15, 2021
Messages
39
Location
City, State
I finally took the time to join the softEOT/DPU group and to try it out on these signals.

This is the one that clinches it, if I didn't goof something up in the process.

Two EOTs were detected and decoded in about 48 minutes, the rest were INV, which is about right from what I can hear.

Next I need to catch some real, legit OTDs on the scanner plugged into the laptop at the crossing.

# MRK BATST TRB CNF
# MOT | || BATCU VLV |
# Time Received SIG SRC ID BP | | || ||| | CMD TYP | | RR SYMB
2022/11/22-15:21:52 12.4 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:21:56 2.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:22:09 0.8 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:22:15 37.2 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:22:16 0.8 EOT 82769 68 0 1 OK 92 1 --- ARM 1 0 ---- ------------
2022/11/22-15:22:23 0.8 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:22:32 40.0 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:23:01 0.9 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:23:09 3.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:23:23 27.6 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:23:52 1.4 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:24:02 67.0 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:24:08 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:24:18 41.4 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:24:45 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:24:51 2.5 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:25:07 47.0 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:25:20 12.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:26:00 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:26:19 144.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:26:45 0.1 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:27:06 0.9 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:27:25 14.0 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:27:35 0.5 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:27:44 2.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:27:54 0.7 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:28:17 1.2 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:29:49 9.5 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:30:04 0.6 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:30:22 70.8 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:30:37 66.0 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:30:46 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:31:26 26.1 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:31:35 80.9 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:32:10 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:32:39 37.6 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:32:55 1.2 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:32:57 1.6 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:33:01 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:33:12 1.4 EOT 48295 114 0 1 NM 40 1 --- ARM 1 0 ---- ------------
2022/11/22-15:33:39 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:34:15 14.0 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:35:22 1.1 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:36:01 0.7 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:37:07 14.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:37:09 65.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:40:01 0.8 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:40:39 6.1 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:40:46 0.6 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:40:55 0.4 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:41:15 1.2 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:41:25 140.2 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:42:12 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:42:35 0.9 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:42:54 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:43:27 0.4 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:43:38 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:43:40 16.7 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:43:46 0.8 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:44:51 104.1 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:47:05 ---- INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:47:09 1.6 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:47:26 4.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:47:54 0.7 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:48:49 36.5 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:48:57 3.9 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:49:04 10.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:49:37 73.7 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:53:09 3.7 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:56:09 0.2 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:57:32 1.6 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-15:57:40 0.5 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-16:01:36 0.4 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-16:06:11 0.3 INV ----- --- - - -- --- - --- --- - - ---- ------------
2022/11/22-16:09:08 7.9 INV ----- --- - - -- --- - --- --- - - ---- ------------
 
Top