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Remote Dispatching the Onondaga Cutoff

A couple of weeks ago, I had the pleasure of serving as Conrail’s Mohawk Dispatcher on Dave Abeles’ HO scale Onondaga Cutoff. Dave’s model railroad is located in northern New Jersey, and I was serving as the “2nd trick” train dispatcher from my home near Pittsburgh.  The “first shift” dispatcher starting the night off, was located in Jacksonville, Florida!

A trio of my locomotives pose for a photo on Dave Abeles' Onondaga Cutoff at CP-280.

A trio of my locomotives pose for a photo on Dave Abeles’ Onondaga Cutoff at CP-280.

First of all, it’s great to be able to join my friends in running some model trains without having to make a six-hour drive in order to do so.  Also, as Conrail’s train dispatchers always worked from a desk in some faraway center, having us working remotely really contributed to the realistic experience Dave is trying to create.

So about that – hop on over to Dave’s website for more info on his railroad. The Onondaga Cutoff (the “OC”) represents a fictional Conrail bypass route around Syracuse, New York, somewhat similar to the West Shore route around Rochester.  His railroad therefore features Conrail traffic that would have been routed primarily over the Chicago Line in the mid-1990s.  The OC is fully-equipped with CTC: all interlocking switches are remote-controlled, and the layout features fully-functional LED train signals.  Control of the switches and signals is via Digital Command Control, using CATS and JMRI software all set up by Nick Anshant.  (All that, by the way, was by far the most difficult, relative to the rest of what I write here!)  For most of Dave’s operating sessions, the train dispatcher for the night sat at a PC in the basement, controlling switches and signals.  Dispatcher, yardmaster, and train crews all use GMRS walkie-talkies that are easily found on Amazon.com.

We knew early on that setting up a remote dispatcher would be easy as far as PC access.  Using remote desktop software like TeamViewer it’s pretty straightforward to give someone in Pittsburgh access to the OC’s dispatcher computer in NJ.  The hard part of this project was figuring out the communications.  After some brainstorming, we thought Skype (which provides free computer audio/video “phone” calls) would be worth a try, and indeed Skype turned out to be the answer.  We discovered that our Midland GMRS radios had separate input and output plugs, normally meant for a headset.  They also feature voice activated transmit (“VOX”) – which means that sound coming out of the PC can be used to transmit the radio.  After some fiddling and configuration, the setup turns out to be pretty easy:

  • From the computer’s sound card, run a cable from sound card Line Out (usually a 1/8″ stereo plug) to the 3/32″ mic input jack on the radio
  • And run a cable from the 1/8″ radio line out into the Line In on the PC
  • For some computers, the Sound card’s mic input might be more reliable.  For Macintosh we found that a USB sound card such as the Griffith iMic provided better signal levels.

With this setup, a computer at Dave’s house could be interfaced with a radio as described, and a Skype call to that computer would then be transmitted over GMRS, and anyone talking on the same frequency would be received by the computer and sent out over the Skype call.

Motorola Desk Mic in action

Motorola Desk Mic in action, at an operating session on my own model RR

The remote dispatcher didn’t need any special setup, other than a computer with a microphone and speakers, with Skype installed.

We wanted to take it a step further – we wanted a realistic way for the dispatcher to have a say in when he or she is transmitting.  We had already purchased tabletop Motorola radio mics of 1980s vintage, that I’d modified to be able to serve as a microphone for our Midland GMRS radios (more on that later).  It turned out to be a fairly simple matter to modify them again so that the Motorola’s push-to-talk button would “enable” the microphone for Skype, so that a dispatcher could have a conversation without unnecessarily transmitting over the radio the entire time.  This came in handy, as one of the regular OC operators goes to college near me, and he came by for part of the operating session.  It was great to be able to chat with him without unintentionally transmitting over the radio.

Yours truly, with my "dispatcher's desk" set up.

Yours truly, with my “dispatcher’s desk” set up. Webcam is visible on the monitor at right, and the Motorola desk mic is to the right of the laptop. CATS screen with the track display visible on the laptop.

Operationally, Dave’s layout depends on a five-track, double-ended staging yard that easily holds 175 cars.  This staging yard is located on a lower level of the layout, and locomotives are added and removed from trains (and scurrying back-and-forth to the locomotive area called the “Island”) throughout an operating session, to give the appearance of different trains rolling over the OC’s main line.  Much of the operation hinges on the successful juggling of locomotives and train consists to provide for the right visual variety of rail traffic to represent the Chicago Line in the mid 1990’s.  For example, a single autorack train is used to represent ML-403, ML-480, and others.  Occasionally, the autorack train is combined with one of two intermodal consists to represent times that ML-480 carried a block of intermodal.  So, it’s the dispatcher’s job to know and understand not only the train schedule for the “model” portion of the layout – “real” eastbounds and westbounds – but the dispatcher is also responsible for the “behind the scenes” work in staging that makes this all possible.

With that in mind, I thought that it would be challenging to keep track of what-is-what in the OC’s staging tracks, especially considering the double-crossover located in dark territory in the middle of tracks 4 and 5 at aptly-named “Midway”.  $25 at Amazon.com solves this problem with the purchase and installation of a web-enabled video camera that Dave placed at Midway for our benefit.  It was fun to be able to sit in my basement as dispatcher, and be able to see some of the “rail action” on the OC in real time.

One last thing worth noting – as with “real” train dispatchers, I “qualified” on the OC by running trains at several operating sessions, serving as train dispatcher once or twice, and by preparing the locomotive plan for the OS that I dispatched remotely.  All of this was invaluable, as it was necessary me to be able to visualize the entire railroad (including all of the areas not represented on the live track diagram), and make changes based on how the operations unfolded for the day.  Ultimately, while the train dispatcher is helping create the illusion of mid-90’s Conrail, part of the dispatcher’s job is making that illusion come alive for all of the guys in Dave’s basement during an operating session, by running a practical train schedule that keeps everyone reasonably entertained!

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Motorola Mic modifications

I modified two Motorola mics – one for each of us.  Initially, the goal for these mics was simply to plug them into the Midland radios so that the “Dispatcher” working on-site didn’t have to pick up a walkie-talkie constantly.  Talking into the table-top mic is easier and more realistic.
Inside the Mic

Inside the Mic

I cut off the Motorola’s RJ-11 connector and installed a 3/32″ micro-mini headphone plug, soldering the black ground wire to the sleeve on the connector, and the red wire to the tip. In order to use the Mic’s PTT button to have the correct effect on the Midland radio, inside the base of the mic, I added a 470 ohm resistor, which when PTT is pressed, shorts the green wire to the red.  For remote dispatching, I found it easier to use a second connection to the sound card – typically 1/8″ mini-headphone jack – and added a toggle switch to cut out the resistor.  PTT still has the correct effect, this time as a simple momentary SPST switch.
Motorola mic with 3/32" adapter

Motorola mic with 3/32″ adapter

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