Question on cell phone stuff

[Wayne Lundberg]

How could I detect the presence of a nearby cell phone? I'm assuming most
are sending out a query pulse every millisecond in search of a matching
signal that would make them ring. So they are transmitting a signal
continuously in human terms. What kind of circuit do I need to develop to
detect nearby cell phones? And in so doing come up with a device to detonate
the detonators plugged into IEDs and other terrorist bombs?

 

[Tim Auton]

How could I detect the presence of a nearby cell phone? I'm assuming most
are sending out a query pulse every millisecond in search of a matching
signal that would make them ring.

Why on earth would they do that? It would be a fantastic waste of
bandwidth and power. Idle cell phones do talk to the network, but only
every several minutes, not a thousand times a second. The rest of the
time it's just listening. The network sends a signal to let it know when
to ring.

Put your phone right next to a TV or stereo. You'll can tell from the
interference exactly how often it speaks to the network.


Tim