Escort Passport SRX Owner's Manual page 10

How Radar and Laser Work
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 reflection
is affected by both the size of the vehicle
and its proximity to the antenna, it is difficult
for the radar operator 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-Band radar, your Passport will
occasionally receive non-police radar
signals. Since these X-Band transmitters are
usually contained inside of buildings 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 abilities are fully
operational.
How Laser (Lidar) Works
Laser speed detection is actually LIDAR
(Light Detection And Ranging). LIDAR guns
project a beam of invisible infrared light.
The signal is a series of very short infrared
light energy pulses which move in a straight
line, reflecting off your car and returning to
the gun. LIDAR uses these light pulses to
measure the distance to a vehicle. Speed is
then calculated by measuring how quickly
these pulses are reflected given the known
speed of light.
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LIDAR (or laser) is a newer technology
and is not as widespread as conventional
radar; therefore, you may not encounter
laser on a daily basis. And unlike radar
detection, laser detection is not prone to
"false" alarms. Because LIDAR transmits a
much narrower beam than does radar, it is
much more accurate in its ability to
distinguish between targets and is also more
difficult to detect. As a result, even the
briefest laser alert should be taken
seriously.
There are limitations to LIDAR
equipment. LIDAR is much more sensitive
to weather conditions than RADAR, and a
LIDAR gun's range will be decreased by
anything affecting visibility such as rain, fog,
or smoke. A LIDAR gun cannot operate
through glass and it must be stationary in
order to get an accurate reading. Because
LIDAR must have a clear line of sight and is
subject to cosine error (an inaccuracy
which increases as the angle between the
gun and the vehicle increases) police
typically use LIDAR equipment parallel to
the road or from an overpass. LIDAR can be
used day or night.
How Safety Warning Systems Works
Safety Warning Systems, or SWS, is a
modified K-band radar signal used to transmit
important driving related information.
From the factory, your Passport is
programmed with SWS turned ON. If SWS is
not used in your area, you can simply turn
SWS reception OFF by using Passport's
EZ-Programming feature.
The SWS system has 64 possible
messages (60 allocated). The SWS messages
your Passport can decode and display are
listed on the facing page.
Note: Some of the safety messages have
been condensed, so each message can be
displayed on one or two screens on
Passport's eight character display.
Since Safety radar technology is
relatively new and the number of transmitters
in operation is not yet widespread, you will
not receive Safety signals on a daily basis
and should not be surprised to encounter
emergency vehicles, road hazards and
railroad crossings that are unequipped with
these transmitters and, therefore, fail to
provide a signal. As Safety transmitters
become more prevalent (the number of
operating transmitters is growing every
day), these Safety radar signals will become
more common.
For more information and details about
SWS safety radar, visit their web site at
www.swslc.com.
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