Radar detector news and frequently asked questions.
Are radar detectors legal?
Radar detectors are currently legal to sell, purchase, own and use in Western Australia ONLY. Radar detectors are legal to own but not USE in Queensland and Tasmania. However, it makes little sense to purchase a radar detector from a supplier outside of Western Australia as test drives and other useful information and support is not available.
Where to mount your radar detector?
High mounting - Good for Radar: higher mounting gives you more "line-of-sight" with the targeting radar. If you do the math, one foot higher mounting gives you an few tenths of a mile extra, maybe even more than 1/2 mile. The average driver isn't likely to notice such a small difference in range, but it might help out in a pinch (detecting brief instant-on at long range)
- Good for detecting laser targeting vehicles ahead, since it can "see" through their windows better etc.
- Bad for detecting laser targeting you, since it is mounted further from the aiming point (front plate/headlight).
Low mounting
- Not as good for radar, but you might not be giving up too much.
- Good for detecting laser targeting you: closer to the aiming points(front plate/lights). More likely to give a laser warning when you are targeted, and you'll have time to slow down if they don't get a reading when you are first targeted, such as if you have a dark vehicle, are using VEIL, they aren't holding the gun steady etc.
- Not as good for detecting laser targeting vehicles ahead, since it can't "see" through their windows as well
How do police radar guns work?
Radar guns utilize the "Doppler principle" to determine speed. They transmit radio waves at microwave frequencies, and when these waves strike a moving object, they are reflected back to the radar gun at a slightly different frequency. The gun then "mixes" the reflected signal with the transmitted signal, and ends up with a frequency that represents the difference between the two. Since the difference in frequency is generally a number of hertz or kilohertz, it is in the audible range, hence the term "Doppler tone". The speed of the moving object can be derived by performing a calculation using the frequency of this Doppler tone and the original transmit frequency.
How do laser guns work?
Laser guns do not use the Doppler principle like radar guns do. Instead, they use "time difference of arrival". The laser gun sends out a pulse, and calculates the "time of flight" for the pulse to be reflected back to the laser gun. Since the speed of light is a known value, the distance between the laser gun and it's target can be calculated by the time of flight. The laser gun takes multiple distance measurements, and by comparing the different distance measurements over time, it can determine the speed of the target.
How do radar detectors work?
In a nutshell: Modern radar detectors are superhetrodyne receivers, similar to a scanner. First, they use a microwave horn antenna to receive the radar signal. The radar signal is generally passed on to a first mixer stage, where it is mixed with a first local oscillator to produce an IF. The IF is generally passed on to one or two more mixer and IF stages depending on the design. Finally the signal is detected, and then handled by the processing and control circuitry to produce a visual and audible alert. Radar detectors usually sweep the first LO (and sometimes the 2nd or third too) in order to sweep the different police radar bands for a signal. They will also contain multiple filter and amplifier stages.
