In message
,
Mizter T writes
I think it's simply the journalist getting in a muddle and jumping to
erroneous conclusions. I don't believe there's any 'long distance'
sensing or reading of Oyster cards going on whatsoever.

I jolly well hope not - I often pass near an Oyster reader when I don't
want it to be read, because I am using a paper ticket. For reassurance:
RFID reading is a classic case where an inverse fourth-power law applies
(because there's roughly an inverse square law for the transmission of
power from the reader to the card, then ditto for the information from
the card to the reader; this isn't perfectly accurate because of
near-field effects, but a fair approximation). I find that an Oyster
card needs to be within a few cm of the reader, so I doubt if it is
feasible to read them at distance of over say 10 cm without a massive
increase in the power levels, which would be a danger e.g. to those with
heart pacemakers.

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Clive Page