Underground Trains


Thread Starter

Cross, Patrick

Dear List

We have an automated electric train system running underground. We communicate to it via a leaky feeeder radio system. I was wondering if anyone has had any experience with alternative methods of communication to trains. For example: is it possible to superimpose the communciation over the power supply.

Thanks & Regards

Patrick Cross
Control Systems Engineer
WMC Olympic Dam
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Schaminee, Bart (IndSys, GEFanuc, Nether

Hello Patrick,

Try to contact Echelon -> LonWorks www.echelon.com
Or GE Harris. www.geharris.com
They do communication over Power Lines.

Bart R. Schaminée
- Netherlands -

This document is provided for informational purposes only.

Anthony de la Rosa

check out www.adaptivenetworks.com they make a range of powerline modems that will surely work for you. I use their AN192 powerline modem to
communicate with a PLC5/15 on a stacker crane. A Digital Alphaserver sends move commands to the stacker crane via a terminal server to an end of aisle modem to the 460v trolley assembly and down to the stacker cranes vertical brushes and to another AN192 on the stacker crane itself.

Communicating with the train using signals riding over the power lines or through the rails is used in a large number of European subways since many
years ago.
Patrick, a very long time ago, I worked for a company that made tunnel rebroadcasting systems, so I have a suggestion.

Why don't you consider spread spectrum technology for the radios and passive repeaters in the tunnels? If you use 2.4 gHz, you may be able to do without the repeaters.

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And is notorious for its problems. Nowdays everything is going onto broadband leaky feeder cables, these carry cellular phone traffic as well as railway communications and control signals.

Leaky feeder cable is not easy to implement, but is predictable. Specialists are able to make an on site inspection and tell you wht you need, and it will work. Power line transmission is sinonomous with 'black magic'.

Power lines are also restricted to a small number of communications channels, whilst broadband leaky feeders can carry a wide range of signals and services.

Pravin Fatnani

well, I don't have the details, but this is the way it is done between Electricity Authorities, using the transmission lines. Its called PLCC -
power line carrier communication.

Pravin Fatnani

Donald Pittendrigh

Hi All

I remember a pal of mine at Siemens telling me one day about an ultra long wave radio system for communication underground, as an alternative to the leaky feeder option.

Donald Pittendrigh
Power line carrier (PLC) systems have been around for some time and are used widely in Europe, mainly on catenary power lines. If it is only data that you need communicate with trains you may be able to use Spread Spectrum Technology.
Kasten Chase Applied Research in Toronto Canada makes a spread spectrum product currently used by two signalling suppliers to communicate with trains in tunnels.

Transit systems want to communicate with portable radios in tunnels and this generally requires the installation of a leaky coaxial cable network. We've also used CATV cable which is relatively inexpensive, and inserted antenna taps (using a special tool) every 60 m with success, for this see Kaval Communications also in Toronto Canada.

Norbert Koot

Here at the Toronto Transit Commission, we used a 3rd rail channel to communicate to trains, but it was notorious for noisy performance. The sliding shoe is not a clean contact, and generates large bursts of AM noise onto the channel (you've likely seen the sparks). We installed a broadband leaky antenna to replace it. Although it too is not perfect, at least the dropouts are fewer. Modern data communications equipment
can typically handle either type of dropout through packet retransmission, but the dropouts are harder to tolerate for voice channels.

Norbert Koot

in my opinion the communication via leaky feeders may be good enough to exchange data at the rate of up to 1 Gb/s, specially if you use unlicensed frequencies such as 58 or more GHz. However the usage of the power lines with a spread spectrum technique able to poll a specified train just with a simple code is attractive. In this case I wonder how to, let me say, "conditionate" the line in order to guarantee such communication without interfering different services present on the line.
Whta do you think about?

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