User Manual

34
Automatic Same Direction
™
(ASD
™
) is a revolutionary radar technology patented by MPH. It
allows the radar to tell the direction a target is moving relative to the radar. So in the two
examples above, the radar would see two different Doppler shifts: +4312 and -4312 cycles per
second respectively. +4312 cycles per second would be converted to +60 mph, meaning that the
target is approaching at 60 mph. -4312 cycles per second could be converted to -60 mph, meaning
that the target is moving away at 60 mph.
This allows the BEE III to do something that other traffic radars cannot do. The operator can
select to only have the radar monitor targets in a particular lane of traffic while completely
ignoring traffic in the other lane. This is particularly important when a “Jersey barrier” is present,
preventing the officer from pursuing traffic in the other lane.
Moving radar theory
Moving traffic radar refers to units that have the ability to function while the patrol vehicle itself is
in motion. They have this ability in addition to their standard stationary capabilities. When being
used as moving traffic radar, the MPH BEE III will simultaneously display both the patrol vehicle
speed and the target vehicle speed. Like the stationary radar, the moving radar is based on the
Doppler theory. However, with moving radar, the signal processing is more involved than with
stationary. The radar receives reflected signals from both the target and the roadway. The target
signal contains information on the combined speed of the two vehicles while the patrol signal has
the information concerning the speed of the police vehicle. The receiver (mixer diode) in the
antenna provides all of this information.