A detector consists of a a simple SHF reciever.
These are usually relatively simple circuits containing a microwave detector (often based upon a Schottky diode) and a comparator that drives an alarm. Such devices will pick up any microwave signal between two and ten Gigahertz so they cover most but not all speed camera's avaiable.
The method of speed determiation in police equipment uses the doppler shift principle, that is the phase change in the returned signal from the the transmitted reference. Unlike proper RADAR the outgoing signal is unmodulated, generating the signal is often just a case of powering up a Gunn diode fitted into a resonant cavity with a horn antenna to give a narrower beam.
A simpler solution, aside from mounting an unshielded microwave oven in the trunk of your car, is a second brake-light switch.
Works wonders for tailgaters! :twisted:
I understand that radar detectors are legal in the states, wonderfull bit of salesmanship that was.... :lol:
You see, the average reaction time to put the foot on the brake is half a second [0.5sec] whilst a quick read of the sales blurb for speed cameras reveals that they stabilise and capture the cars velocity in around one-tenth of a second [0.1sec]. Basically the buzzer gives the driver no warning just sounds to let you know you've been busted.
The penalty for interfering with the operation of speed camera varies but rest assured using any form of electronic jamming by accident or design could well prove unpleasent in a court of law. :cry: