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Monitoring Railroad RF Data

Frequently Asked Questions about using ATCSMon to monitor Radio Code Line

  • Q: Technically speaking, how does ATCS Monitor work?
  • A: The devices in the field (referred to as an "MCP") communicate with a base station (referred to as a "BCP") via two-way radios by sending and receiving short bursts of computer data. The data transmitted from an MCP to a BCP is called an indication, because it is indicating something happening in the field such block occupancy, switch alignment, etc. The data sent from a BCP to an MCP is called a control, because it is requesting (control­ling) something in the field, such as a signal or switch alignment. For an example of what this data burst sounds like, see the SoundSamples section.
  • Q: If it's possible to decode the information, is it also possible to affect movements?
  • A: No. ATCS Monitor is a read-only application. It receives an audio signal from the output of a high-quality radio receiver that is able to tune the appropriate frequencies, digitizes the audio waveform at 44.1 kHz, and de­rives the data by analyzing the digitized stream. The program intentionally contains no code to create any control information, and no code for audio signal modulation. Since it contains NO encoding algorithms and cannot produce any audio output, it absolutely CANNOT be used to perform or assist in the performance of any kind of radio transmission. No version of the program has ever been produced with the capability to produce a signal suitable for transmission, nor will one ever be produced. Even if it could, the railroad wayside equipment would not allow conflicting routes to be set.
  • Q: Can train symbols and other information available to the dispatcher be displayed?
  • A: That type of logistical information isn't gathered or distributed to the devices in the field. ATCS Monitor only had the ability to monitor information that is broadcast over-the-air to and from the devices in the field. Since an electric switch doesn't care about train symbols and such, it is not broadcast, and thus not available for us to display.
  • Q: I live within a few miles of a high-traffic railroad line. Can I monitor my area and provide an internet feed?
  • A: Possibly! There's more info as you read on in the Wiki, but you can also ask about your area in the ATCS Monitor Yahoo group email list.
  • Q: What do the railroads think of this?
  • A: There's varying response. Not much of it has been terribly negative, and in fact, many signal system maintainers utilize the software to monitor and troubleshoot their own systems.
  • Q: Couldn't this technology be misused dangerously in the wrong hands?
  • A: No more so than a variety of other means. All we can really do is see when a train is coming. You could think of dozens of simpler ways to achieve that: field observers, webcams, and defect detectors calling out train passage over the voice radio are among them. No useful detail about the train location, speed, or content is obtained. See the Open Letter to the Industry for technical detail.

Did you know you can go to any of a dozen websites to see the exact position of any commercial airliner in the US? Do a Google search on flight tracking, or take a look at the current New York situation.

-- GaryHahn - 31 Oct 2006 - Majority contribution by Brian Swan