How Red Light Cameras Work; How Speed Cameras Work - Escort Passportmax Owner's Manual

Understanding Your Detector

How Red Light Cameras Work

Red light cameras use three basic things: a camera, a
device to trigger the camera and a computer. An
intersection may have more than one camera to
monitor traffic from multiple directions. The trigger is
typically a series of wires buried just beneath the
surface of the road. These wires are separated by a
pre-set distance to create a magnetic field or
induction loop. Once a vehicle is in the intersection,
the loop or circuit becomes closed and alerts the
computer to take a picture.
In some states, tickets are issued to the car's owner,
no matter who's actually driving. In this case, the red
light camera only needs to photograph the vehicle's
rear license plate. In other states, the actual driver is
responsible for paying the ticket. In this case, the
system needs a second camera in front of the car to
get a shot of the driver's face.

How Speed Cameras Work

There are several types of fixed position speed
cameras used, including radar, laser, induction-loop
and photo-based. Radar and laser based cameras are
typically mounted near the road and transmit a short
range signal across the lanes monitored. Since this
signal is transmitted across the road instead of down
the road like with many handheld systems, detecting
them in time is critical.
Another technology used is an induction loop system.
This type of system utilizes wires buried just beneath
the surface of the road to trigger a computer that
calculates speed between the two points. Photo
based systems take two sets of pictures of all passing
vehicles between two separate fixed locations. Both
sets of photographs are date and time stamped,
which enables the system to calculate average speed
between the two locations.
Fixed speed cameras can also be set up to monitor
one to four lanes of traffic in the same direction. To
achieve this, a sensor is installed in each lane, and a
wide angle camera lens is used to photograph the
vehicle that is speeding.
How GPS Works
Developed by the U.S. military,
the global positioning system (GPS) is
made up of 24 orbiting satellites. There
are at least four satellites visible at any given
time every day. A GPS receiver is designed to locate
and receive data from four of these satellites. These
data include the distance to your location from each
of the satellites. Once the distance from each satellite
is known, the receiver can calculate and pinpoint your
exact location.