User Manual

Interference Information and Precautions

There are several factors that can influence the operational behavior of Doppler radar. These

influences can be natural or man-made. A knowledgeable operator will not be confused by these

external influences.

1. Natural Influences

Driving rain or blowing dust can cause a scattering effect, or diffusion, which can

decrease the effective range. A driving rainstorm may affect the patrol display. Close

observation of the patrol vehicle speed is recommended.

Terrain can affect the range. Should the patrol car be on a slight decline, the antenna

could be shooting short of the target vehicle. If on a slight incline, it could be shooting

over the target vehicle. Range may be shortened in either case.

Strong reflectors can cause target readings that are the same as the patrol speed when in

the moving mode. To avoid this problem, the BEE III detects these harmonics and inhibits

their display.

Note: The harmonic detection feature may cause occasional blanking of legitimate target

speeds when it is the same as the patrol speed, or a multiple of it. If the operator suspects

this is the case, he can change his speed. In any case, the range of any other target is not

changed; for example, if the closest target is blanked due to the coherence detector, the

BEE III will not acquire and display a weaker, more distant target in its place.

2. Man-made Influences

These influences are normally the most troublesome because they generally involve

electronic signals that may cause spurious displays, or they may lessen the effective

range.

Power transformers, radio transmitters, neon lights, etc generate electronic noises. These

influences generate a phenomenon that can cause radar to display a false reading or

lessen the effective range. The RFI indicator will show the presence of strong RF fields

caused by local transmitters. To prevent possible readings caused by the interference, no

target speed will be displayed when this indicator is on. Intermittent signals may also be

caused by electrical noise produced by the vehicle’s ignition system or by vehicles with

noisy alternators. The RFI detection circuitry will recognize this noise as well and

suppress the speed readings. However, the officer needs to be aware that these sources

of electrical noise may affect the operation of the radar.