WHAT IS POP RADAR
NEW RADAR GUN IS SOLD UNDER
The POP™ mode isn't error prone; it's error
ticket writers have been bragging about their new radar;
They say it nails detector users without warning.
their MPH Industries model BEE™ III, with its POP™
mode, gave them an advantage for a while. But now V1 has
full-time POP Radar Protection on two bands. Yet a problem remains.
When operated in its POP mode, those radars also produce
erroneous speed readings every time.
we believe MPH Industries knows this feature is faulty.
Why else would it advise, in the accompanying Operation
and Service Manual, as follows:
note of caution: Information derived during the POP
burst is non-evidential… Citations should not be issued
based solely on information derived from the POP burst.”
actual testing of a BEE III in our laboratory, we quickly
learned why MPH Industries is covering itself in the fine
print. The POP mode is fundamentally flawed. It consists
of a lightning-quick radar burst, over and done with before
a radar detector can pick up the signal. We consistently
measured the POP duration at 67 milliseconds (that’s 0.067
for accuracy, that burst is over the speed limit for the
BEE III’s own internal components.
traffic radar units rely on a Gunn oscillator to produce
a stable, reference frequency for the microwave beam.
This reference frequency must be held constant
throughout the entire reading. Here’s how radar works:
A microwave beam at the reference frequency is transmitted
toward the target. The radar unit then compares the reference
beam to a reflection of that same beam after it has bounced
off a moving vehicle and returns to the radar unit. The
difference between the reference frequency and the reflected
frequency—known as the Doppler shift—gives the speed of
the moving vehicle.
Gunn oscillator we’ve ever tested can go from “off” to
“on” and back “off” again in 67 milliseconds while simultaneously
holding its frequency. This is basic physics. To be “on,”
electrical current must flow through the oscillator. As
the current begins flowing, it inevitably heats the component.
While the device’s temperature is changing, so is its
frequency. After a second or so under power, the device
will reach its constant operating temperature and it will
hold steady at its design frequency.
during the short cold start from ambient temperature to
operating temperature, the device is literally out of
control. Component makers don’t even bother to quantify
the frequency change—called a start-up chirp in electronic
jargon—because Gunn oscillators are designed as steady-state
devices; they’re not intended for cold-start use.
does this start-up chirp mean for ticket accuracy? The
answer is really unknowable, because it’s influenced by
a number of variables. For example, how far away is the
target vehicle? The longer the distance, the greater the
error. What’s the target speed? The slower it is, the
larger the percent error. Which way is the target moving?
The error adds to the speed of vehicles approaching the
radar, and subtracts from vehicles heading away.
MPH Industries has stepped into foul territory with the
POP mode. In its zeal to defeat detector users, it has
created a radar unit operating outside the accepted principles
of engineering. Then it has tried to paper over its own
technical recklessness by advising police doperators,
sotto voce in an obscure section of the manual,
that they can’t use the BEE III’s key selling feature
for its plainly intended purpose.
number one: Given the widespread ignoring of manuals,
will anyone even read that warning?
number two: If they read it, will they heed it?
Industries, in its quest for corporate profits, is playing
an unconscionable game with its law-enforcement customers.
Traffic radar is bought for one reason; it’s a ticket
machine. Promising a feature, then telling the police
after the sale not to use that feature for writing tickets,
is pure bait-and-switch. Moreover, it dangles a temptation,
a moral hazard, that threatens to corrupt enforcement.
MPH Industries must be compelled to recall all BEE
IIIs at once and disable the fundamentally faulty POP