What you should know about radar
How Traffic Radar Works
Traffic radar uses a radar beam to measure speed. Think
of the beam as a searchlight. It’s invisible because it’s made
of microwaves instead of light, but otherwise it acts very
much like a light beam. It travels in straight lines. It’s easily
reflected. It scatters as it is passed through dust and
moisture in the air. And — this is essential — it has to hit
your car before it can determine your speed.
Radar can’t see around corners or through hills. It can’t
see you when you are behind another vehicle. When in
the clear, how strongly your vehicle reflects determines
how far the radar can read your speed. Generally, larger
vehicles reflect more strongly than smaller vehicles.
Truck are “visible” on radar farther away than cars.
The principle on which radar operates is absolutely
reliable. Radar equipment, on the other hand, is only as
good as the quality of its design and manufacture. Traffic
radars tend to be unreliable. They’re cheaply made and
therefore vulnerable to many interferences that cause false
readings. And, compared to the military and weather radar
which have rotating antennas, traffic radars are vastly
simplified. This simplification means that traffic radar
cannot tell one car from another. The operator has to do
that, and since the operator can’t see an invisible beam any
better than you can, he frequently doesn’t know which
vehicle’s speed is being read. This is a source of many
undeserved tickets.
How Radar Detectors Work
A radar detector works like a radio tuned to microwave
frequencies. Valentine One is an extremely sensitive radio,
and it’s tuned exactly to the frequency bands used by all
traffic radar in the U.S. — X band, K band, Ka Band, which
includes photo. Moreover, it has two antennas, one aimed
forward and one rearward, so that it can locate the radar.
Because Valentine One is so sensitive, it can easily find
radar from the scattering of the beam, and it can find these
scatters a long time before the actual beam hits your car.
The only exception is Instant-on radar.
How Instant-on (Pulse) Radar Works
As a defense against detectors, many radar units can be
operated in the Instant-on mode, also called the Pulse
mode. This means the radar is in position, but it is not
transmitting a beam. So it cannot be detected. When the
target is within range, the radar operator switches on the
beam and the radar calculates the speed, usually in less
than a second. This calculation happens too quickly for
the target (you) to respond in time.
Still, you can defend against Instant-on by recognizing it
when the operator zaps traffic ahead of you. Valentine
One’s great sensitivity — and your attention to the nuances
of its warnings — gives you at least a sporting chance.
The Difference Between X Band and the K Bands
X-band alerts (“Beep”) are often found at long distances.
K and Ka bands are usually detected at closer range, and
alerts on those frequencies are much more likely to be
radar. So Valentine One makes a different sound (“Brap”)
to warn you of these more urgent threats (bogeys).
What are False Alarms
Since all radar detectors are simply radios tuned to
the microwave frequencies used by traffic radar, they
automatically sound their alert whenever they encounter
signals on those frequencies.
The problem is, other devices that are not radar are also
operating on radar frequencies. A detecting radio must
respond to them too. Every response indicates a threat, a
bogey. How can you tell the difference between radar and
what people commonly refer to as false alarms? Your
judgment is the only way. But here are the basics:
•
X band:
A catch-all band, still used regularly in some
areas by traffic radar, but heavily populated by sensors
for supermarket automatic doors and other nuisance
signals. In shopping areas, expect door sensors. But
know the territory. Unless you’re sure that X band is
not used locally for radar, stay alert until you’ve
identified the bogey.
•
K band:
Maybe radar, maybe not. Supermarket door
sensors operating on K have recently begun corrupting
this formerly reliable warning of radar. Another non-
radar source — cheapie radar detectors that pollute by
transmitting on K.
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