Batboard

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What is a FRED?

Charles Blythe
KD5TKR

There are plans for train control systems that would be based on GPS to someday replace track circuit based signaling and control systems.

FRED is a railroad term for the rear end telemetry and marker device that hangs on the last car. The "F" politely is for "flashing" but another "F" word was applied by crews when it meant the elimination of the caboose and associated jobs. The "RED" is "Rear End Device"

Today most FREDs are two way brake pipe telemetry and remote control emergency brake application devices now usually called "EOT" for "End of Train" and the associated locomotive equipment is called "HTD" for "Head end Telemetry Device". They operate on a 452/457 MHz frequency pair. Each EOT has a serial number that is selected on the locomotive HTD and an "arming" procedure establishes communications between the 2 units.

It's been a while since I worked on RR stuff (including FREDs), but to the best of my knowledge, the radio's themselves do not have GPS in them. That does not mean that you can't add something to the accessory port and use it as part of an ID string. Maybe by now there is something, but I am not aware of it.

-WEC

Ok, I knew about the EOT, just not the FRED. I picked up a VHF Spectra from a former railroad employee, and have been listening to the AAR freqs for a while. I'd also like to know more about the Defect Detectors. Are they stationary or mounted to the train as well?

Charles Blythe
KD5TKR

Defect detectors are mounted in a small shed by the wayside. The talking ones usually operate on the RR's road freq. When they know where they are, railfans use them to alert them a train is coming.

There was a recent thread on here about detectors:

http://batboard.batlabs.com/viewtopic.php?t=44385

GP38:

From your description of the air-powered FRED it sounds like it is a WABCO ATX. I have heard about them but I have not seen one. I read the AAR rule waiver info for them that says they only produce a 0.2 psi loss in trainline pressure and a turbine failure will not cause an emergency brake application. I wonder how they are working out in the "real world" and what the users think of them? Not needing to worry about a dead battery is good but not if it means one more leak in the trainline to contend with.

I don't know of any AAR Loco radio with a built in GPS but the data capability of most radios supports an add-on accessory.

Here is a snippet from a person on the inside of the industry that makes EOT's. The original discussion was about NS "dual band" units, but the last sentence is relevant to this thread:

"Quantum has the "RED HOTS", EOT receivers, on nearly every NS
locomotive. These receivers are dual band, VHF and UHF, and at one
time could handle all three formats, VHF DTMF (called NS slow), VHF
FSK (NS fast), and UHF FSK (AAR). They were later cut back to just do
the FSK formats. Quantum started making HOT hardware about 4 years
ago, and EOT hardware (boards for Sou Tech units) about 3 years ago.
They have just recently come out with their own EOT unit (it's the
red one). That EOT (and soon Wabtec's) have GPS receivers and
transmit their location in addition to the normal messages. Location
is transmitted about every 4 minutes."

Doug

K2HZ, indeed it was a UP ATX. I both like and hate them. They are nice because, obviously, as long as there's air in the brake pipe they never die. The bad thing is, if you've got a long (75+ cars) cut with an ATX on one end, you can't just go ahead and arm him once the engine/s pull to clear. As soon as the air dumps, you lose comm with ATX FRED and have to go back to him later to poke him. This can mean walking...yes, 75+ cars once you've made your last hook at the head end and the train is built.

As far as durability, I haven't had one fail yet. They seem to be built pretty solid, as much as battery pack FREDs. They are a lot lighter without those lead cells, though. I figured the air loss had to be miniscule, as I'm still trying to find where the turbine exhausts. So far, nothing. Not even a pinhole.

Hello.

The air comes out of the base.
The space between the 4 screws is the exhaust.

F.R.E.D....Freight Rear End Device.

Pacific National (in .au) uses a seperate radio for AVL.

GP38-

Chances are they may be talking thru some nearby UP loco's with all the new Harris data radios that are also used with the remote diagnostic features (FIRE? system with the EMD's?).

Another thought, is that with all the GPS/Sat enabled refrigator cars that UP/BNSF came out with in the last couple of years, they may have something going on there.

Either way, its something that hasn't been advertised too much by UPRR.