Sample Form

Compute Range Given Speed Error

The form below computes the range between a target and radar for a given SPEED ERROR (due to the Cosine Effect) based on target speed and radar distance off the road (target lane). Other calculated parameters include time to target even with radar and target acceleration (mph/sec and kmh/sec). Target Speed entered must be a whole number (no decimal point).

Sample Form Results

Cosine Effect Speed Error

Target Speed	Radar Off Road (target lane)
60 mph 97 kmh	35 feet 10.7 meters

Cosine Effect
SPEED ERROR RANGE TIME to
Even Speed
Measured Acceleration

-0.5 mph
-0.8 kmh 269 feet
82 meters 3.1 sec 59.5 mph
95.8 kmh 0.32 mph / sec
0.52 kmh / sec

Cosine Effect SPEED ERROR	RANGE	TIME to Even	Speed Measured	Acceleration
-0.5 mph -0.8 kmh	269 feet 82 meters	3.1 sec	59.5 mph 95.8 kmh	0.32 mph / sec 0.52 kmh / sec

In the above example when a target is traveling at 60 mph a radar or ladar 35 feet off the road (target path) has a -0.5 mph cosine error when the target is about 269 feet (3.1 seconds) from the radar. The closer the target gets the greater the cosine error (the lower the radar measured speed).

Police Traffic Radar Handbook
Chapter 4.2