5. Is pacing accurate if it is done during dusk or at night?
Pacing is much more difficult in the failing light of dusk or in complete darkness, unless the officer is right on your tail. In darkness,  the officer’s visual cues are reduced to a pair of taillights. Also, if an officer paces a speeder’s tail lights from far back in traffic, she’ll have trouble keeping the same pair of taillights in view.
6. How do the road conditions affect pacing?
Pacing is easiest and most accurate on a straight road, with no hills, dips, or other obstacles and where the officer can see your vehicle continuously as she follows you. This allows her to keep her car at a constant distance behind you while she paces your speed. Hill, freeway interchanges, dips, curves, busy intersections, and heavy traffic make for a poor pacing environment. All of these obstacles can be used to challenge the accurate pacing of your vehicle.
7. How does radar work?
Radar guns aim an electromagnetic signal at a target vehicle and pick up the return signal reflected off the vehicle. The Doppler effect causes the frequency of the return signal to shift by an amount dependent on the relative speeds of the source of the original signal and the target. Speed radar devices measure the frequency of the reflected signal and compare it with the frequency of the original signal to determine the speed of the target vehicle. A radar beam varies in width comparative to it’s length‑the further the radar’s “zone†extends from the unit the wider it will be. Thus, there must be some evidence in a radar case that the radar was not inadvertently picking up any other moving objects that may also have been within the radar’s “zone.â€
8. How is radar used? What are the types of radar equipment?
Although many brands of radar units are in use, they all fall into two types, car mounted units that can be operated while the officer’s vehicle is stationary or moving, and hand‑held radar “guns†often used by motorcycle officers in a stationary position.
9. What are car‑mounted radar units?
Most radar antennas used in patrol vehicles are shaped something like a side‑mounted spotlight without the glass on the front.
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