Erik Reuter wrote:
...
> The only thing I can think of that might possibly work would be that
> each RFID chip delays a random amount of time before responding to a
> query from the reader (and this random time changes each time for each
> RFID chip that is queried). Then if the reader keeps querying over and
> over, eventually, by luck, it should get a clean signal from each RFID
> chip. But this seems that it would get very inefficient if you had
> hundreds of RFID chips in close proximity.
>
> Anyone else have any ideas how it works?
Not I. But in your system it would be enough to keep
querying until it was unlikely that any new chips were going to
be "heard". All the system has to do is keep a list of all the
chips clearly heard on each query, and merge the lists at the
end. It would be easy to calculate the probability that a chip
was remaining hidden in the collisions, and go until it was
sufficiently small.
An alternative method with time delays is for the query
to specify which classes of chips should delay for how long.
(e.g. delay := .000001*(bit 3 + bit 5 + bit 11 + bit 12))
---David
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