On Thu, 21 Feb 2013 10:50:10 +0000
"Clive D. W. Feather" wrote:
It would have to be a big linear amp. These transponders are used with
the train over them, so if the idiot is standing 1m from the platform
edge he needs about a factor of 800 amplification to reach the strength
of the transponder signal.

A fair point. Though you often don't need much to cause enough interference
in a digital signal to make it unusable if there is poor or non existent
error correction.

In any case, the only purpose of these transponders is to confirm the
train's exact position. It works something like this. The train starts

Is that how the new Met system will work too?

Spud