Radar? I've always thought those MPH readouts were for verifying your 1/4 mile trap times?81 Corvette said:
Total urban legend.81 Corvette said:
You've made my head hurt!Mac said:Hib pretty much said what I was gonna but I can add a few things... maybe one or two things the technical writer might be aware of... or not.
For those who don't know, I'm a cop and I'm certified expert at estimating speed, including using radar and laser. Although I'm no longer working highway patrol, I did a couple of years as a professional ticket writer.
Fiberglass is effectively invisible to radar but the metal of the frame, the rad, the motor, the birdcage, etc etc etc... every bit of it reflects the radar. The lower profile which a Shark presents helps a bit but by no means are Sharks invisible to radar.
Radar isn't the be-all, end-all by any stretch of the imagination. There's a reason why some many tickets get tossed out of court despite "good" radar results. If you sit still and watch one of those radar trailers as displayed in the picture, you'll observe most of what I'm about to describe.
Most police radar have a single antenna which transmits a radar signal that spreads out in a cone shaped pattern in front of the antenna and reflects off of anything and everything inside that pattern. The same antenna is used to receive the reflected signal. The speed, wave length and modulation of the transmitted signal are known so the receiver is set to exclude that signal. If the modulation of the reflected signal is Doppler-shifted by movement within the pattern, the instrumentation measures the shift and displays it as a speed.
Doppler shift? The sound of the train's horn changes as it goes past because the movement of the train affects the sound waves, etc. As stated above, the radar receiver is set to exclude the known transmitted signal. In other words, if nothing is moving, the signal isn't changed and nothing displays as a speed. Practically speaking, there is never a time when nothing is moving.
Radar measures EVERYTHING within it's range which means erratic and/or unreliable readings are very common. If a bird zooms past the radar antenna, it will be measured. If a raindrop falls, it will be measured. The radar sets have a gain control which the operator uses to exclude most of these unwanted readings but if it's set too high, everything is excluded so most of the time, gain is set mid-range.
The radar set will display the strongest signal which it receives. That's why I said fiberglass is effectively invisible- the metal behind it will produce a much stronger signal than the plastic fantastic so the fiberglass become irrelevent.
So if a tractor-trailer is approaching you from behind, being that it's a larger mass of metal, the radar will likely display it over your Shark... or it might display a combination of your speeds... or the difference between them. What's to stop the transmitted signal from bouncing between your vehicle and the tractor trailer? What if that bounced signal ends up stronger than that of your Shark or his truck? Errant reading!
Then there are times when the radar set will display speeds which are completely wrong. A car doing 30 mph shows as doing 60 mph... or there's no car but a "ghost reading" (yep, that's what they call it) shows. False readings are common, especially if gain is set low. What's to keep the cops from making a mistake? Well....
The way it's supposed to work is the cop uses the radar to confirm his visual estimate of speed. In other words, the cop should use his judgement rather than trusting the technology. Some cops leave the radar running and use the audibel tone it generates to draw his attention away from his donut & coffee long enough to see you speeding. Others leave the radar in "stand-by" and use the 'instant-on' once he's already eyeballed you just to confirm his visual estimate. If you get stopped by the guy doing the latter, you're getting a ticket and chances are you won't get out of it in court.
NOW, the sweet curves of the Shark do make it much more difficult to use laser for speed enforcement. Laser is strictly "line of sight" so a reflected signal is necessary or no reading is obtained. In most cases, cars have upright licence plates, grills, turn signels, etc.. so getting a reflection isn't difficult however the angles of the front end of Sharks tend to bounce the laser up into the sky or down onto the ground.
I could ramble on about laser too but you've probably read enough of me for one day.
-Mac
Gotta love those arrows. It's very programmable (& easy to program)
Some states in my mind just generally Suck. You know, the states you don't even like to drive thru. Virginia is one of them as is Massachuchetts. Why TF would any state put a moniker on them that most people can't even spell?Culprit said:
Dealers:
