Railroad repeater station I.D.

This just occured to me, I have never heard a railroad repeater or station broadcast an I.D. Are commercial stations like this exempt from doing so?

Railroads do not use repeaters, they use remote controlled bases.
The ID need not be broad casted separately but by FCC and FRA rules each communication is to be started as for example:
Union Pacific engine 4666 to dispatcher C, or Metro North train 1868 to District F.

FCC rules require mobile radio systems to identify by call sign either during each exchange of communications or every 30 minutes in the public safety services and 15 minutes in the business services.

Railroads have an exemption to the use of the FCC call sign if they identify by the name or recognized abbreviation of the railroad and fixed station location or train symbol, engine number etc..as required by FRA regulations.

A few RRs, mainly short lines, do use "repeater" (officially called "mobile relay") stations and these may have an automatic morse code or recorded voice call sign identification device to comply with the FCC 15 minute ID rule.

An exemption, okay, I thought it was something like that.
And Dutch, on my railroad issued system map, there are several locations marked with the word "Repeater".

I agree with Dutch insofar as the Union Pacific RR uses remote bases (towers) for the TD to talk with the trains/crew/MOW, etc. When you tone up the TD depending upon where you are, the TD will see an alert on their dispatch screen showing that a request to communicate has been noted at such and such tower (place, location). The TD will then communicate through the tower which has the communication request. There are times when the TD will be speaking to a train or crew on a tower and a train 50-100 miles away can hear the TD but not the crew. If the tower were a true repeater, then you would be able to hear both sides of the conversation (am I right on that on Dutch?) (not to mention a real pain to listen to conversations such as Dispatcher 76 on the Shafter and Elko subs for nearly 400 miles, I'd go nuts).

There are also times when the TD will call a train from a tower just within range of the train from an outlying tower. If he/she comes in scratchy or low volume, we'll ask the TD to try another tower. Once he/she does, they come in loud in clear. I think your RR map just has repeater on it for simplicity sake. Most RR's don't delve to deeply into this arena.

a repeater listens on one frequency and transmitts everything it hears out on a different frequency. Therefore a repeater would not be able to hear the dispatcher unless it also had a phone line input. A remote base is just that, remote. I believe the remote bases are controlled by (talked to and listened via) either a twisted pair (phone line) or microwave satelitte. Anyone know? Ed

Usually Microwave satellite

PBX channels are usually true repeaters.

So explain to me why, here at the far eastern end of the railroads district 2, I can hear the district 3 dispatcher talking to a train at the other end of district 3 ? Both districts share the same frequency, and they walk on each other a lot. Wouldn't remote bases prevent this? And whats with the weird offset for the train to dispatch input freq?

truman wrote:So explain to me why, here at the far eastern end of the railroads district 2, I can hear the district 3 dispatcher talking to a train at the other end of district 3 ? Both districts share the same frequency, and they walk on each other a lot. Wouldn't remote bases prevent this? And whats with the weird offset for the train to dispatch input freq?

In the sense of walking on each other, actual repeater vs. remote is no difference. Actual radios are broadcasting out from both instances. As has been explained, a repeater system is another radio talking to the repeater, and then getting repeated by the repeater radio. A remote system is either a microwave system or a phone line talking to the remote, and then the remote broadcasts out. As a lot of the career guys have complained about, the off set is to get the dispatch and road channels seperated. It is essentially reversed with either system. Train to remote via air waves, remote to dispatch via micro/phone line. A lot of the career guys on here have complained about the off-set channels and getting orders, etc. from dispatch, and possibly missing a train ahead in emergency, etc. on the road channel. Yes the off-set clears up the radio, but creates problems elsewhere. Ideally, a radio that monitors multiple channels simultaneously would alleviate this. A lot of the career guys have started carrying portable scanners for this reason. They do make multiple channel monitoring radios, but changing out how many locos would cost big $$$. I know the medical helocopter in our local area monitors at least 3 channels simultaneously. I was flying with them once, and we were listening to the aircraft band, their dispatching channel, AND the Superbowl from an FM radio station simutaneously on the way back from taking someone to a trauma center. It just sounded like 3 different speakers playing in my helmet. If you are talking an off-set dispatch channel, I'm guessing that it maybe more or less a combo remote/repeater. Our county's EMS dispatch system is that way. We have 5 towers countywide. They only keep 1 "open" since we are not simucasted-yet. So if they have the "south" tower opened and we are in the north part of the county, the 911 center can hear us, but no one else unless they have our radio transmit channel. If we need to talk to another crew coming in to back us up, etc., we can request that the dispatcher open the cooresponding repeater (if they're not bright enough to do that on their own. Different story.) to re-broadcast out over the air if we are still out of talk-around/simplex range.

Without knowing the specifics of how your system works in terms of dispatcher base locations it is difficult to respond. But, here are some general comments on trade-offs with setting up a RR radio dispatch system.

If each dispatcher has a single base in the center of their district with a high tower or on a mountain top, it is likely there will be considerable overlap into the next district including areas where the adjacent dispatcher may be stronger than the local dispatcher.

As you suggest, an alternate solution is use of multiple remote bases spaced along the line throughout each district where each has minimum antenna height and power to cover about a 10-15 mile radius. This can be designed to minimize overlap although there still will be some problems from the last base in each district.

Another issue is that the signal from a distant base may be strong enough to cover a mobile signal at the dispatcher's receiver.

So the tradeoffs are:

Use a different channel for each district. The downside is that train crews are required to remember to switch channels and can not hear anything that is going on in the next district ahead until they switch.

Use a common system Road channel but a separate, unique, Dispatcher channel for each district. CSX recently implemented this in former CR districts. Crews do not like the fact that they may miss important messages on the Road channel while they are talking to the Dispatcher on the other channel.

Use a common channel for Road and Dispatcher transmit but a separate channel for trains to talk back to the dispatcher. This is great for the dispatchers that don't need to listed to Road channel chatter and their reception is not stepped on by adjacent dispatchers. The train crews have the advantage of always listening to the Road channel but the downside is train crew reception of the dispatcher is still likely to be stepped on by other units while they are attempting to copy a form.

So, there is no one best solution for all cases. A decision has to be made on the best compromise for a particulr RR's operations.

Okay, understood. I think.
What I meant by weird offset was the actual width of the offset, which is .360 meg. Is this to save space and stay within the band parameters?

truman wrote:Okay, understood. I think.
What I meant by weird offset was the actual width of the offset, which is .360 meg. Is this to save space and stay within the band parameters?

If you are asking about the offset for a train to dispatcher channel, it can be anything except an adjacent channel that might "bleed over". It is just a case of finding an available clear channel.

If it is a repeater or PBX input channel where the base has to be able to simultaneously transmit and receive then a spacing of about .600 or greater is best with about .400 as an absolute minimum to allow the antenna duplexer filters to keep the repeater transmitter signal from interfering with the mobile signal input to the repeater receiver.