Fine or no fine?

[boomer]

Didnt mean to sound condescending, was mainly making it simple and clear for some readers who may not know about such things... saves further questioning by others!

...

i got lost at 'preface'

[McJim]

so when are the yanks/japs going to unveil the stealth sprotbike?

GSX117R?

[Max Preload]

I do also know radar does not have to reflect of metallic or even particularly solid surfaces (e.g. rain radar) but I was under the impression that the objects needed to be angled as to bounce back the transmissions to the sender

There's always going to be something perpendicular to the waveform for a signal to return, albeit a weak one. I don't think the waveform is square either (althought the newer digital ones might be), so part of it will always be perpendicular to the target also.

The first ever ticket I got in NZ was for doing 146 down SH1. I queried the device in use and how it locked onto targets, mainly as I knew I was doing more like 170 at the time. It may be that the radar technology has changed since then, but I did have a written response from the relevant office stating that the unit tracks one vehicle and one vehicle only, and cannot show multiple speeds. They could have been lying, of course.

That would likely have been with the older 50mW Hawk units - how long ago?. The reason for the low reading may have been what is referred to as the COSINE effect (the adjacent side of the vector triangle is registered speed - finally all those hours of high school trigonometry pays off lol) because the target direction is not accounted for in the mircowave units, so unless you're moving directly towards the unit your speed will register low (advantage target!). Although it may have just not acquired a lockable signal fast enough, because that speed difference would have required quite a significant angle to the patrol direction.

The current (I believe) Stalker DSR units can track 2 targets simultaneously and patrol speed and direct relative to patrol (limited to behind or in front). There is PATROL speed, STRONGEST signal and FASTEST signal readouts, each indicating orientation to the patrol i.e.fastest behind, strongest in front of patrol etc. and I *think* there is no lock for strongest (perhaps one of our resident donut munchers can advise on that aspect). How the readout is interpreted and assigned to any particular vehicle is down to the operator competence and/or any underlying need to fill quota.

[Renegade]

It's a remarkable assumption to say that things like radar guns (especially in-car ones which are affected by the police vehicle speedometer calibration, tyre wear, tyre pressures and so on)

Are you sure? even if police car is parked and the radar on stationary mode? i think your wrong.

are deemed to be accurate provided they have been tested within the previous twelve months. In the UK, items do have to be formally calibrated every twelve months, but the calibration must be confirmed by a series of manual calibration checks at the start of each shift, and proof of that must be provided. .

So do the nz police radars, every shift they are used, and fill in the log book after testing is complete.

paranoia, paranoia, everybodies coming to get me!!

[Sanx]

Are you sure? even if police car is parked and the radar on stationary mode? i think your wrong.

Well obviously not, as it should have been blatantly obvious by the comment I made. I was refering to situations in which the car is moving and, should you have read the thread, I've already been told I was wrong by Speedie as it is the radar unit itself that measures the vehicle's speed rather than simply taking a read from the car's own speedo.

So do the nz police radars, every shift they are used, and fill in the log book after testing is complete.

Really. Very interesting, as I have a letter dated yesterday that states precisely the opposite.

Logs demonstrating the laser speed measuring device was calibrated at the start of the shift cannot be supplied. There is no requirement for officers to calibrate the measuring device and therefore no such check was performed.

So who's wrong?

paranoia, paranoia, everybodies coming to get me!!

Everybody's. If you're going to take the piss, at least do it grammatically.

[davereid]

Police radar cannot really be compared to the radar used on boats or at airports etc. Other than the fact they rely on a reflected signal from a target, they are completely different.

Boat radar works by sending a short pulse of energy. By measuring the time for the signal to travel to a target and return you know how far away it is. And as you have a very directional antenna, you know what direction it is. To calculate speed, you need to measure the distance to the target, wait a period of time and measure it again.

So.. boat radar can see lots of targets, and distinguish betwwn them as it can measure distance, and direction.

Police radar uses doppler shift techniques. With doppler shift you transmit energy at a known frequency, and you measure the frequency of the refleted signal.

This gives you instant data on target speed. But, you don't know what your tarket is. You only roughly know the direction, and you have no idea at all of the distance to the target.

And if you have two targets with the same relative speed towards the radar, regardless of difference in distance you will see only one. (Which one is a guess !)

While police regularly use radar in traffic, from a technical point of view, its not really good enough to use when there are multiple targets.

Look at my web page www.eslnz.com/radar.html for a better explanation.

[Cr1MiNaL]

Everybody's. If you're going to take the piss, at least do it grammatically.

lol actually its "Everybodys' " the ' before the s shows possession .. but never mind.

[mbazza]

Thanks for the link to your website. Very good information clearly explained. Thanks. Cheers.

[Sanx]

lol actually its "Everybodys' " the ' before the s shows possession .. but never mind.

No it doesn't, you cheeky bugger. "Everybody's" either means belonging to everybody or everybody is, depending on context. Everybodys' means - literally - belonging to everybodys.

[Pancakes]

so when are the yanks/japs going to unveil the stealth sprotbike?

GSX117R?

From the link below; U.S. F117A Nighthawks, also known as Stealth fighters, swoop largely undetected through radar because their "radar-invisible" paint and angular exterior minimize reflected signals.

http://www.sandia.gov/isrc/F117.html

[scumdog]

From the link below; U.S. F117A Nighthawks, also known as Stealth fighters, swoop largely undetected through radar because their "radar-invisible" paint and angular exterior minimize reflected signals.

http://www.sandia.gov/isrc/F117.html

Speaking of such, did anybody seeee the Mythbusters episode where they tried everything the knew of to beat a radar - and didn't??

Some of the ideas and devices were hilarious, I couldn't believe there was so many old-wives tales about how to beat a radar out there - and people believed them!

[swbarnett]

Why?
Does the physical and financial pain hurt less?
And if so how?

Because I value my freedom and ability to think over and above my ability to walk. If I had to choose between a dabilitating brain disease and quadraplegia it'd be quadraplegia every time.

[swbarnett]

It doesnt take long for it to figure out what is "stationary".

Somebody correct me if I'm wrong but as I understand it the doppler effect can only show you how fast an object is moving relative to you, not it's absolute speed. The speed of the vehicle changes the emitted and received frequency.

[jimbo600]

Speaking of such, did anybody seeee the Mythbusters episode where they tried everything the knew of to beat a radar - and didn't??

Some of the ideas and devices were hilarious, I couldn't believe there was so many old-wives tales about how to beat a radar out there - and people believed them!

I think it was about beating laser as opposed to radar, and yeah some of the myths were amazing if not downright idiotic. I mean who the hell would drive with a mirror ball hanging from the rear view mirror. And CD's sheeit. I see cars in NZ with CDs all over them. How the crap do they think that that is going to work.

[Jantar]

And CD's sheeit. I see cars in NZ with CDs all over them. How the crap do they think that that is going to work.

A CD is designed as a laser reflector, so having CDs all over the car will make it easier to give the cop's laser a target. I'm sure that the HP appreciate the help.