Reed tracks

[Peter]

Could somebody be kind enough to explain 'reed tracks' many thanks.

Reed systems are a form of FDM. The same transmit and receive principal is used for a reed track but instead of being sent down a cable, the given frequency is sent down the rails to be detected by the receiver. Discrimination and a certain level of immunity is achieved because the receiver is looking for the specific frequency.

Without looking it up, I cannot remember how many frequencies are used for these. They are available for use as jointed and jointless tracks. In the past they were used for dual electrified areas but there have been questions over their suitability for this. That said, all of the tracks for two miles out of Paddington (25kV OLE next to LUL DC traction) use them with no problem.

Hope that very quick overview helps, but if you have more specific questions, we'll see what we can do. They are covered in the Network Rail Signal Maintenance Specifications and the Train Detection Handbook.

Peter