Radar Detectors and Radar Signal Jamming
A conventional radar detector, which detects police radar with a simple radio receiver, is a completely passive device. It simply makes out the presence of radar. A more active role in eluding the police is played by sophisticated detectors. These devices, in addition to the basic receiver, have their own radio transmitter that produces a jamming signal. The signal is identical to the original signal from the police radar gun, but additional radio noise is also mixed with it. On account of this, the radar receiver gets an unclear echo signal and an accurate speed-reading cannot be made.
More modern radar gun systems make use of less obvious bandwidths instead of the easily detectable frequencies. Such guns use quick bursts at what has been termed as the K-band range, instead of a constant broadcast. If other speedsters have already been caught, a sophisticated radar detector can detect these signals.
There is also a light-sensitive panel in modern detectors that detects the beams from lidar guns. As the beam doesn’t carry well over long distances and the beam is much more focused, lidar guns are more difficult to evade than traditional radar. The car is most likely to be already in the beam's sights; by the time a detector makes out the presence of the laser beam. One method that people use in order to evade these systems is by trying to reduce the reflectivity of their cars. Since a black surface absorbs more light, it reduces reflectivity. Special plastic covers that are supposed to reduce the reflectivity of license plates are also available.
A laser jammer works more or less in a similar fashion as a radar jammer. The detector has its own in-built light emitting diodes (LEDs) that produce a light beam of their own, in addition to a light-sensitive panel. When this beam is shone on the lidar system, the receiver is unable to detect any reflected light and is, therefore, get a clear speed-reading.
An LED sends out a reflective signal in order to jam the laser light. The frequency of the beam produced by the LED is similar to that of the laser light on the gun and also has some additional electronic 'noise'. The reading thus produced is an unintelligible one and cannot be used to prosecute a suspected speedster.
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