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How Radar Works
Traffic radar, which consists of micro-
waves, travels in straight lines and is easily
reflected by objects such as cars, trucks,
even guardrails and overpasses. Radar
works by directing its microwave beam
down the road. As your vehicle travels into
range, the microwave beam bounces off
your car, and the radar antenna looks for
the reflections.
Using the Doppler Principle, the radar
equipment then calculates your speed by
comparing the frequency of the reflection
of your car to the original frequency of the
beam sent out.
Traffic radar has limitations, the most
significant of these being that it typically
can monitor only one target at a time. If
there is more than one vehicle within
range, it is up to the radar operator to
decide which target is producing the
strongest reflection. Since the strength of
the reflection is affected by both the size
of the vehicle and its proximity to the
antenna, it is difficult for the radar oper-
ator to determine if the signal is from a
sports car nearby or a semi-truck several
hundred feet away.
Radar range also depends on the
power of the radar equipment itself.
The strength of the radar unit’s beam
diminishes with distance. The farther the
radar has to travel, the less energy it has
for speed detection.
Because intrusion alarms and motion
sensors often operate on the same
frequency as X, and K-band radar, your
PASSPORT will occasionally receive non-
police radar signals. Since these X-Band
transmitters are usually contained inside
of a building, or aimed toward the ground,
they will generally produce much weaker
readings than will a true radar encounter.
As you become familiar with the sources
of these pseudo alarms in your daily
driving, they will serve as confirmation
that your PASSPORT’s radar detection abil-
ities are fully operational.
How “POP” Works
“POP” mode is a relatively new feature for
radar gun manufacturers. It works by
transmitting an extremely short burst,
within the allocated band, to identify
speeding vehicles in traffic. Once the
target is identified, or “POPPED,” the gun
is then turned to its normal operating
mode to provide a vehicle tracking history,
(required by law).
NOTE: According to the operator’s
manual from the radar gun manufac-
turer, tickets should not be issued in
POP mode.
How Radar Works How POP Works