Elektor Electronics mag had a GSM phone sensing circuit earlier=
 this
year.

Just a variation on a standard radio frequency sniffer circuit. =
 You
may be able to adapt a GDO (Grid Dip Oscillator) circuit to sense=

900/1800 MHz signals.

Colin
--
cdb, bodgy1@optusnet.com.au on 11/12/2003

I have always been a few Dendrites short of an Axon and believe=
 me it
shows.

Light travels faster than sound. That's why some people appear=
 bright
until they speak!

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