Frequently Asked Questions

In this section:

Introduction

Below are common questions that are asked by people new to ATCSMon.

Application Specific Questions

Dispatchers Display

Much of what needs to be known about reading a dispatcher display is summarized in this graphical representation by Brian Swan, originally built for the Rochelle Railroad Park public display. Displays vary a bit from this template, but overall a good reference.

Why do I see only Clear signals?

Q: Why don’t I see any other signals except for green on the display? What about Approach indications?

A: The dispatcher only has the ability to request a proceed indication from the devices in the field. A proceed indication is distinctly different from a clear signal. A proceed indication is really any other signal at a control point except for a stop. It’s important to note that the dispatcher requests a signal, he doesn’t actually control it directly. In reality it is up to the logic in the field at the various control points to determine what the appropriate signal to display is. It will make this decision based on block occupancy, switch alignment, etc. The same logic applies with any other controls a dispatcher can send to a control point. A dispatcher can request that a control point line a switch into the siding, however, if it is not safe to do so (for example, a train moving over the switch) the control point will not act on that request. So, when the dispatcher requests a proceed indication at a control point, the signal system may in reality display a stop signal because the next block is occupied, or an approach if next signal is Stop, etc. Likewise, the MCPs in the field will only ever report back a proceed indication, so that is all that can be shown on the display. From the point of view of the dispatcher, all he or she really cares about is if the trains he controls can move forward or not.

What do the various colors on the display mean?

Q: Why do station names light up Red and Blue?

A: A station name in Red indicates that an indication was sent by the remote control point to the base station. Indications contain status information about the control point, such as block occupancy, switch alignment, signal indication (proceed or stop), etc. A station will light up blue when a control is sent to it. Controls contain the requests from the dispatcher, such as creating a route, lining a switch, or to turn on a snow melter. When the dispatcher is lining a route for a train, it’s not unusual to see a series of stations turn blue from the control message, then have them turn red as the stations send back status information. You may also see other station colors, such as Orange which indicates that some other type of radio traffic was sent to or from the station. You will also see White or Yellow, which indicates that we are unable to receive any information about that station.

Q: How come I see stations in blue for very long distances, but only the nearby stations light up red? Or some stations almost never show anything?

A: Controls (which make the station show blue) are transmitted from a tall, powerful, and centrally located base station (BCP) that can easily transmit to a large number of control points. The indication information (which makes the station show red) comes from lower-powered radios located at each control point (MCP). Since these are radio signals, atmospheric conditions can affect how well they propagate, meaning that at times (particularly at night) you will receive data for a much larger section of railroad than at other times.

False Indications or No Indications

Q: Why so some stations rarely or never show anything happening?

A: It depends on our radio reception. Some stations on a layout may never show activity if they use a frequency for which we don't have a radio, or a different protocol, or are simply out of range.

Q: Why is there sometimes a train, but no occupancy shown on the display, or vice versa?  Or trains passing restricting signals?  Or other impossible situations?

A: This is an imperfect, amateur monitoring system. The hundreds-of-dollars in equipment spent to bring this display to you is no match for the tens-of-thousands-of-dollars (or more!) spent by the railroads on radio towers, high-end receivers, transmitters, cabling, etc. If we miss a message telling us that a train is there, or is not, then we miss it and cannot update the display until the next valid message is received.

Q: Why do trains disappear into some sidings on the display, only to reappear on the other side?

A: Some sidings may be “Non-Bonded”, meaning that they are not connected to the signal system to provide block occupancy.   Rather, the dispatching computer assists the dispatcher in marking those sidings as occupied.

Radios, Scanners, and Antennas

Scanner Reception

Q: I have been taking my scanner out with a Radio Shack mag-mount antenna and have been listening to the local NS BCP here in Douglasville, GA. I get plenty of ACKS and some indications and a smidget of controls here and there. My first question may be a silly one, please forgive me. Does weather play a big part in how well I receive data? For example, I seem to do a lot better at receiving traffic on a clear cool night rather than a warm sunny day. Second question and perhaps Mark Landgraf can provide some insight into this one: I can hear the BCP just fine here, but receiving the MCPs along this line is difficult at best. I don't even get errors or anything when tuned to 897.9375 here. All the relevant MCPs have the same type antennas. I'm not sure if I need a better radio or better antenna.

I have a Uniden Bearcat BC80XLT with a Radio Shack mag-mount antenna on the rooftop of my car. I can sit almost right next to the antenna on some and receive nothing in ATCS. The scanner picks it up but that's it. And the BCP I don't have a problem picking up. Any thoughts are appreciated.

A: Yes, weather definately effects reception. You ought to see what snow and sleet does to otherwise good reception. Having the leaves off the trees for winter is also a big plus.

With regard to sitting under the MCP and hearing nothing, well, it is possible to be too close (especially with radios that have consumer front ends on them) They can be readily overpowered by strong local signals. How do the adjacent MCPs come in? A better radio is certainly a viable option. Many folks use the Icom PCR-1000 ($400) which has a built in descriminator tap. The 1000 is a fine radio for our purposes. It is basically an off the shelf ATCS ready radio. Other folks use a variety of models made by Motorola and MDS. While many of the professional grade radios can be had for under $100, they usually require some degree of bench work before they are suitable for ATCS work. The one notable easy exception to this statement is the 900 mhz Maxtrac units. The convertion into a BCP radio only requires the reprogramming of the freqs and the movement of a jumper inide from voice to data. The 800 mhz Maxtrac convertions into an MCP radio are considerably more involved. The MDS radio is probably the best and cheapest radio out there (usually under $50), but is the hardest to obtain. Convertion of the MDS units is not overly difficult. Your short term solution would be to park between the MCPs not under them.

If you are not already using the Analyze Signal function of ATCSmon, you should play with it in an attempt to minimize your error rate by adjusting your volume. This may improve your MCP signal reception.

(Answer from Mark Landgraf)

Programming/Development Related

Visual Basic Forms, etc, in place of TrackBuilder for Displays

Q: Would it be possible for ATCS Monitor to use Visual Basic forms or graphics with layers support (Photoshop or Paint Shop Pro or other formats) as dispatcher displays? I think it may be possible to interface ATCS Monitor to tell lines or layers to do things (e.g. ThisTrack^?.color=green, ThisSwitch^?.normal=invisible, ThisSwitch^?.reverse=visible). This would have the advantages of eliminating the need for TrackBuilder, allowing the display to mimic the actual physical map of the tracks, allowing the background to contain details such as roads, crossings, "you are here", etc. A VB form could contain a text area with data from MCP locomotives, or even display signal aspects with a click (assuming my second question is possible).

A: While it would probably be possible to do a GIS type display that would encode a real map, Trackbuilder contains a lot of data above and beyond just the graphics. How this interlocking and it's components interact with the adjacent track sections and signals.

ATCSMon on [insert favorite platform here]

Q: Are there any efforts to port ATCS Monitor to Linux, or publically-available code that will at least decode ATCS transmissions?

A: I doubt you'll ever see Dave Houy release the code, but he has been very accomodating of our needs. The MCP's already have Lat/Long on them, and by placing the lat/long on TB3 somewhere/somehow, we could probably get him to include a DDE pass-thru of this info. This would then allow you to start to drive movements in a GIS mapping type environment. Although, you would probably have to do a layout in order to get the logic to work correctly. With the UP locos identing themselves and their locations every minute, you could actually start to show the headend trains, as well as every other parked loco on the property. If or when a radio capable tablet or palm becomes available, and there is enough interest among the members of the group, we may be able to persuade Dave to support the software on two platforms.

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-- BrianSwan - 30 Oct 2006

• ATCS_HowToReadTheDisplay.pdf: Graphic explaining much of what is shown on the ATCS Monitor Dispatcher Display.