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How Radar Works
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How Radar Works
Traffic radar, which consists of microwaves,
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 reflec-
tion is affected by both the size of the
vehicle and its proximity to the antenna, it
is difficult for the radar operator to deter-
mine 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-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 gener-
ally 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 abilities are fully operational.