Pocket Radar PR1000, Руководство пользователя и инструкция

Страница: 7 / 12

POCKET RADAR™
Radar Measurement Challenges (Con’t)
This off angle speed measurement error is referred to as the COSINE error, named after
the mathematical function that allows you to calculate the exact speed versus angle.
The measured speed will always read lower than the actual speed as you move off the
centerline of the path of the moving object. For small angles, this error will be very small. This
is why you see police officers pointing their radar along the direction of the road; not down a
side street pointing sideways to the road.
Example
On a typical college or high school baseball field, right behind the backstop, if you stay
within 12 feet to either side of the centerline between the catcher and pitcher, any pitches
that are less than 90 MPH will read within 1 MPH of the true speed. As you move further off
the center line, the readings will become less accurate and you may miss the measurement
entirely. On Page 5, there is a chart and table of the angle versus the percentage error. This
error will occur with any type of speed radar.
6
46
˚
=30%
37
˚
=20%
26
˚
=10%
18
˚
=5%
8
˚
=1%
46
˚
=30%
37
˚
=20%
26
˚
=10%
18
˚
=5%
8
˚
=1% 0
˚
Each degree from center will cause your
speed to read the noted % lower.