GENESIS-VPD™ USER’S MANUAL
25
Rev. 09/04
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Erroneous speeds appear to track with the
engine speeds.
Interference regardless of the source is neither
additive or subtractive of a valid target reading.
Interference will not impact on teh accuracy of the
radar unit, but it will impact on the operational
range. If a member establishes a solid tracking
history, as referred to in section 6.4, it can be
established that interference was not present at
the time of the speed reading.
5.2.1 Angular Interference (Cosine Effect)
The cosine effect causes the system to display a
speed, which is lower than the actual vehicle
speed. This condition exists when the target
vehicle’s path is not parallel to the antenna,
including conditions such as the vehicle
traveling on a curve or a hill.
As the angle between the beam of the antenna
and the target vehicle increases, the displayed
speed decreases. Ideally, an angle of zero (0)
degrees is preferable, because the displayed
speed is the actual target vehicle speed.
However, in all uses of police radar, the radar
device is always at a slight angle to the target
vehicle to avoid collisions.
Figure 5.2.1 An angle between the antenna and the
target vehicle causes the cosine effect.
