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Understanding Your Detector
Interpreting Alerts
Although GT-7 has a comprehensive warning system,
only experience will teach you what to expect from
your detector and how to interpret what it tells you.
The specific type of radar being used,
the type of transmission (continuous or instant-on)
and the location of the radar source affect the alerts
you receive.
How Radar Works
Traffic radar, which consists of microwaves, travels in
straight lines and is easily reflected by objects such
as cars, trucks, and 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 and K band
radar, your detector 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 the device’s radar
detection abilities are fully
operational.
CAUTION: Overconfidence in an unfamiliar area can be
dangerous. Likewise, if an alert in a commonly
traveled area is suddenly stronger or on a different band
than usual, speed radar may be set up nearby.
Alert
Explanation
Detector begins to sound slowly; rate of alert
You are approaching a continuous radar source
increases until it becomes a solid tone. The
aimed in your direction.
signal meter ramps accordingly.
Detector emits short alerts for a few seconds
An instant-on radar source is being used ahead
then falls silent, only to briefly alert and fall
of you and out of your view.
silent again.
Detector suddenly sounds a continuous tone
An instant-on radar or laser source is being used
for the appropriate band received.
nearby. This kind of alert requires immediate
attention.
Detector sends a brief laser alert.
Laser is being used in the area. Because laser is
inherently difficult to detect, any laser alert may
indicate a source very close by.
Detector receives weak signals. Signals may be
A moving patrol car with continuous radar is
a little stronger as you pass large, roadside
overtaking you from behind. Because these
objects. Signals increase in frequency.
signals are reflected (reflections are increased by
large objects), they may or may not eventually
melt into a solid point, even when the patrol car
is directly behind you.
Detector alerts slowly for a while then abruptly
You are approaching a radar unit concealed by a
jumps to a strong alert.
hill or an obstructed curve.
Detector alerts intermittently. Rate and
A patrol car is traveling in front of you with a
strength of alerts may be consistent or vary
radar source aimed forward. Because signals are
wildly.
sometimes reflected off of large objects and
sometimes not, the alerts may seem inconsistent.
Detector alerts intermittently; rate and
A patrol car is approaching from the other
strength of signal increases with each alert.
direction, sampling traffic with instant-on radar.
Such alerts should be taken seriously.
Detector gives an X band alert intermittently.
You are driving through an area populated with
radar motion sensors (e.g., door openers or
burglar alarms). Since these transmitters are
usually contained inside buildings or aimed
toward or away from you, they are typically not
as strong or lasting as a real radar encounter.
The following examples will give you an introduction
to understanding your detector’s warning system for
radar and laser alerts.
How POP Works
POP 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 radar gun manufacturers, tickets
should not be issued in pop mode.
How Laser Works
Laser speed detection is actually light detection and
ranging (LIDAR). Laser guns project a beam of
invisible infrared light. The signal is a series of very
short infrared light energy pulses that move in a
straight line, reflecting off your car and returning to
the gun. Laser 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.
Laser is a newer technology whose use is not as
widespread as conventional radar; therefore, you may
not encounter it on a daily basis. And unlike radar
detection, laser is not prone to false alarms. Because
laser 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 laser, however. Laser is much
more sensitive to weather conditions than radar,
and a laser gun’s range will be decreased by anything
affecting visibility, such as rain, fog or smoke. A
laser gun cannot operate through glass, and it must
be stationary to get an accurate reading. Because
laser must have a clear line of sight and is subject to
cosine error (an inaccuracy that increases as the
angle between the gun and the vehicle increases),
police typically use laser equipment parallel to the
road or from an overpass. Laser can be used day or
night.
How TSR Works
GT-7 includes a new boost in anti-falsing software to
eliminate excessive alerts from erroneous X and K
band sources, such as traffic flow monitoring systems.
These systems, which are becoming more widely
used in several countries, generate K band signals to
measure the flow of traffic on a given road.
Unfortunately, most detectors see this as a
real threat and will alert you to it
unnecessarily. Our new proprietary software, TSR,
intelligently sorts, ranks and rejects these types of
false alarms automatically. The result is ultimate
protection without excessive false alarms.
