At 06:33 PM 10/15/2002 +1300, [EMAIL PROTECTED] (Peter Gutmann) wrote: >Scribe <[EMAIL PROTECTED]> writes: > > >"The technology 'sees' the shapes made when radio waves emitted by mobile > >phone masts meet an obstruction. Signals bounced back by immobile objects, > >such as walls or trees, are filtered out by the receiver. This allows > >anything moving, such as cars or people, to be tracked. Previously, radar > >needed massive fixed equipment to work and transmissions from mobile phone > >masts were thought too weak to be useful." > >Isn't this what CDMA already does using RAKE receivers (different fingers >track multiple signals, so it uses multipath as a feature rather than a >problem). Presumably, with rather more signal processing than is simply used >to improve signal quality, it'd be possible to use the capability to track >interfering objects.
Yes, this is very similar to a RAKE receiver. Its also similar to the passive radar systems the U.S. recently accused a former Soviet republic of selling to Iraq. Passive radars are particularly good at spotting current generation stealth aircraft. Being passive, typically using distant powerful shortwave broadcast signals, means its much harder to spot the receiving sites. steve
