Western Railroad Discussion > End of Train EOT Train telemetry radio question

Several of us in NorCal have noticed telemetry transmissions sounding with 4 quick measured bursts of data in quick succession.  Usually on 457.9375 Mhz, the EOT frequency.
This is quite unlike anything we have heard before, such a repeatable pattern.  This is not brake pipe charging or changes in speed.  Seems to happen almost randomly.
Has anyone else noticed or heard this ?
Rick Somers
Redding, CA

Rick2582 Wrote:
-------------------------------------------------------
> Several of us in NorCal have noticed telemetry
> transmissions sounding with 4 quick measured
> bursts of data in quick succession.  Usually on
> 457.9375 Mhz, the EOT frequency.
> This is quite unlike anything we have heard
> before, such a repeatable pattern.  This is not
> brake pipe charging or changes in speed.  Seems
> to happen almost randomly.
> Has anyone else noticed or heard this ?
> Rick Somers
> Redding, CA
Perhaps it's a secret government code being sent to agents in the field. A new spin on a "Numbers Station" on shortwave.
https://en.wikipedia.org/wiki/Numbers_station

EOT repeaters are becoming more prevelant due to train length.

They can be wayside mounted and/or used on DP locomotives.

Depending on the make/model EOT and whatever is happening, it can transmit more often - especially true if there is an issue with the accelometer, air issues and anything else that the computer thinks it needs to transmit.

Posted from iPhone

Any info on which trains this is related to? The Redding Turn, or the now standard giant train, or the NB Intrmaodal with the DPU's. That might help characterize what's going on. Rick is from the Redding area so I would think this is for the UPrr activity in that area.

Trackside repeaters would be a new development, that would cause the same effect everytime a train goes through. The DPU repeaters make some interesting noises when there's two trains in the area, ergo the question about the NB Intermodal.

So that there is no confusion...

Repeaters mounted in the DP’s sound and work the same as the wayside ones (except as described below).

There are repeaters for DP operation but those are mounted wayside, and obviously a different data packet and freq.

DP mounted EOT repeaters use to be standalone boxes that were physically installed in the nose cabinet.

The new style ones are integrated into the electronics like every other box is. These allow you to repeat a specific EOT and not the entire world (smart repeater vs dumb repeater).

UPS Z trains now carry a spare EOT on the train in a specific location and due to motion may or may not turn on and emit data until the battery runs out.

For the wayside repeaters, they will retransmit anything it hears (dumb repeater) but most will also transmit data back on the UP network and are logged for troubleshooting purposes.

Some neat stuff out there.

Occasionally after an intermodal picks up a cut on the rear, I've seen a EOT flashing on the previous rear of the train, as well as the EOT on the new rear of train.  Would two EOTs cause the sound Rick is hearing?

mapboy

Rick2582 Wrote:
-------------------------------------------------------
> Several of us in NorCal have noticed telemetry
> transmissions sounding with 4 quick measured
> bursts of data in quick succession.  Usually on
> 457.9375 Mhz, the EOT frequency.
> This is quite unlike anything we have heard
> before, such a repeatable pattern.  This is not
> brake pipe charging or changes in speed.  Seems
> to happen almost randomly.
> Has anyone else noticed or heard this ?
> Rick Somers
> Redding, CA


I've noticed this recently at Cisco, Ca on the Roseville Sub. Several chirps in a row on the EOT band. I never timed the duration it but it seemed to happen every x amount of minutes even when there are no trains with in 30+ miles of the location. I spent the better part of 4 hours at that location last weekend and it happened the entire time.

Kinda funny, I just drove down to Costco in Redding, just as I passed Home Depot the radio belched out the four sqawk pattern. I would think it's the Local switching but didn't drive over to check it out. Redding is pretty crowded on a Friday afternoon and it's better to drive up the Canyon as early as possible these days.

Thanks everyone, glad someone else is hearing this also.  Interesting info on the repeaters, I'll have to check that out.
Most Tuesdays evenings some of us get together to relax a bit and watch the Redding Turn do some switching in the Redding Yard, from 5 pm til they are through, usually around 7:30 pm.  The 4 chirps are quite loud while we are at the Yard, very consistent signal strength.
I drove to Dunsmuir 2 weeks ago Sunday and heard the 4 chirps in the Sac Canyon also.
Yesterday we went over to Keddie and Williams Loop, then up the BNSF Highline to Poison Lake.  Didn't hear the 4 chirp pattern the whole day.

donner_dude1 Wrote:
-------------------------------------------------------

> I've noticed this recently at Cisco, Ca on the
> Roseville Sub. Several chirps in a row on the EOT
> band. I never timed the duration it but it seemed
> to happen every x amount of minutes even when
> there are no trains with in 30+ miles of the
> location. I spent the better part of 4 hours at
> that location last weekend and it happened the
> entire time.

Without more data, this is speculation:  If there is a stationary EOT repeater, it may be programmed to ID itself every so often.  Many "regular" repeaters are programmed to do this.  A lot of analog repeaters will ID themselves with a burst of Morse Code transmitting the repeater's FCC callsign.  I believe that used to be a regulatory requirement.  However, another purpose that such ID'ing serves is to let people monitoring the channel know that the repeater is up and functioning.  At one place where I worked, the repeaters were programmed to self-ID every 20 minutes.  Because data can be transmitted so rapidly on digital radios, some digital radios can even self-diagnose and transmit that data periodically.

Doesnt work that way for EOT repeaters

Posted from iPhone

Keep in mind DPU also uses the EOT channel to communicate, Might be hearing a DP set talk

Nope, it does not.

DP’s are close in freq but does not reused them EOT freq

Posted from iPhone

A somewhat recent discussion with the frequencies, not about the DPU repeating the EOT though, that was a different discussion:

Date: 07/16/19 11:16
Fred Freqs

https://www.trainorders.com/discussion/read.php?1,4829858,4830182#msg-4830182