Rador while moving?

[Jeff_89]

Well, this question may seem stupid but can cops use radar while driving. Only ask this because whenever i drive with certain people they always slowdown to the speed limit(only speeding like 10-20 anyways). I ask why and they say so they dont get a ticket. Can someone help me out on this one. Thanks.

[Brian P]

I presume you mean radAr ...

YES, they most certainly have moving-mode radar.

[Rob MacLennan]

I've been pulled over by an officer who was initially going the other way. He had a RADAR dome mounted over his driver's side door and quoted a speed that was within 2 or 3 Kmh of what I knew I was doing. Yes, it's possible. All that is necessary is a calibrated speedometer on the cruiser.

[spankayf]

Well, this question may seem stupid but can cops use rador while driving. Only ask this because whenever i drive with certain people they always slowdown to the speed limit(only speeding like 10-20 anyways). I ask why and they say so they dont get a ticket. Can someone help me out on this one. Thanks.

Many cruisers are equipped with front and rear antennas so they can clock you coming and going either direction.

[FiReSTaRT]

I got nailed for going 5 over by a cruiser going in the opposite direction. Since I was still young and uneducated, I paid the $30+- ticket and got nailed with a 20% insurance rate increase.

[Jeff_89]

thx for the input

lol, omg, i didnt even realised a spelled radar wrong, must not of been paying attention.

[masalma]

I got nailed for going 5 over by a cruiser going in the opposite direction. Since I was still young and uneducated, I paid the $30+- ticket and got nailed with a 20% insurance rate increase.

$30 how long ago was that?

yes radar works while moving, most cruisers are equipped with two sensors, front and rear facing.

Nas

[FiReSTaRT]

2001-2002. I think it was my last year @ LU before I transferred to UofT. Be careful if you're ever in Sudbury... They're as bad as the TPS and it's 400km away in case you need to show up in court.

[CopMagnet5oh]

I've been pulled over by an officer who was initially going the other way. He had a RADAR dome mounted over his driver's side door and quoted a speed that was within 2 or 3 Kmh of what I knew I was doing. Yes, it's possible. All that is necessary is a calibrated speedometer on the cruiser.

there's no " calibration " of the speedometer. and for this matter, no calibration of their lasers, whoever said ask when it was last calibrated and ask if the cop is certified on use of this device is on crack, every cop is assumed to be trained as part of being a cop and these devices do not go out of calibration with use, its either broken or working.

[Rob MacLennan]

there's no " calibration " of the speedometer. and for this matter, no calibration of their lasers, whoever said ask when it was last calibrated and ask if the cop is certified on use of this device is on crack, every cop is assumed to be trained as part of being a cop and these devices do not go out of calibration with use, its either broken or working.

Drop your tire pressure ten pounds, then see how accurate your speedo is.

[GMAN]

The radar you are talking about is called an MDR (Moving digital radar). The unit is placed on the dash. It shows the speed of approaching vehicles, as well as the speed of the cruiser.

Now the problem for speeders is that this unit can be set for a certain speed, such as 15 over and placed in an automatic mode. That means if you enter the beam exceeding the 15 k the radar counts down for 6 seconds. It then records the highest speed during those 6 seconds and displays it.

So seeing the cruiser and braking like hell, is not going to save you if it is in the automatic mode. On the other hand if you just overtook a tractor trailer, it is going to record it's speed before yours, unless you are right on top of the cruiser.

[spankayf]

The radar you are talking about is called an MDR (Moving digital radar). The unit is placed on the dash. It shows the speed of approaching vehicles, as well as the speed of the cruiser.

Now the problem for speeders is that this unit can be set for a certain speed, such as 15 over and placed in an automatic mode. That means if you enter the beam exceeding the 15 k the radar counts down for 6 seconds. It then records the highest speed during those 6 seconds and displays it.

So seeing the cruiser and braking like hell, is not going to save you if it is in the automatic mode. On the other hand if you just overtook a tractor trailer, it is going to record it's speed before yours, unless you are right on top of the cruiser.

Except.... digital radar also has a Fastest Speed Mode meaning the radar will record the trucks speed and yours... there's no protective "shadow" from the truck.

[GMAN]

Except.... digital radar also has a Fastest Speed Mode meaning the radar will record the trucks speed and yours... there's no protective "shadow" from the truck.

Have to disagree with you on that one!

[spankayf]

Have to disagree with you on that one!

I can supply the speeding bike for the test .....

[Qualdoth]

thx for the input

lol, omg, i didnt even realised a spelled radar wrong, must not of been paying attention.

Apparently you still aren't. It's "must not have" or "must've not"

[NiteshadeTA]

grammar Nazi.

Huked on fonix werced fer me!

Nites

[Muchacho]

Does digital radar or any other type of radar that works while the vehicle is moving have the capacity to know if you are speeding while both vehicles are in a curve?

I ask because a police officer told me he pointed his radar at me while I was in a curve and told me I was speeding. However, I was suspicious that he was able to "point" anything at me while he was driving so I did not admit anything. He ended up not giving me a ticket for speeding.

[spankayf]

Does digital radar or any other type of radar that works while the vehicle is moving have the capacity to know if you are speeding while both vehicles are in a curve?

I ask because a police officer told me he pointed his radar at me while I was in a curve and told me I was speeding. However, I was suspicious that he was able to "point" anything at me while he was driving so I did not admit anything. He ended up not giving me a ticket for speeding.

No it doesnt and there's 2 errors that can come into play

1) The radar beam travels in a straight line, neither bending around curves nor following the contour of hilly terrain. If the antenna is not properly positioned, it may seem to clock an approaching car when, in fact, it's clocking another car in the background

2)Moving radar tries to do a more complicated jog than stationary radar, it is subject to all the errors of stationary radar, plus several additional errors that apply to it alone. Moving radar calculates target speed by subtracting patrol speed from the closing speed of the target. Therefore, anything that produces a low evaluation of patrol speed will automatically result in a high speed reading of target speed

A stationary object adjacent to the road, such as a building, or road machinery, or even a sign, makes a more efficient reflector than horizontal pavement. Therefore the radar uses that reflection as the basis of patrol speed.

If this reflector were positioned straight ahead on a collision path, the patrol speed estimate would be close enough. But the further the object is located off a direct line to the target, the lower will be the estimate of patrol speed. This is a simple trigonometry problem relating to the cosine of the angle between the target and the ground reflector, hence the name Cosine error. Since Cosine error always makes patrol speed seem smaller than it actually is, it always acts to raise the reading of target speed.

[Rob MacLennan]

No it doesnt and there's 2 errors that can come into play

1) The radar beam travels in a straight line, neither bending around curves nor following the contour of hilly terrain. If the antenna is not properly positioned, it may seem to clock an approaching car when, in fact, it's clocking another car in the background

2)Moving radar tries to do a more complicated jog than stationary radar, it is subject to all the errors of stationary radar, plus several additional errors that apply to it alone. Moving radar calculates target speed by subtracting patrol speed from the closing speed of the target. Therefore, anything that produces a low evaluation of patrol speed will automatically result in a high speed reading of target speed

A stationary object adjacent to the road, such as a building, or road machinery, or even a sign, makes a more efficient reflector than horizontal pavement. Therefore the radar uses that reflection as the basis of patrol speed.

If this reflector were positioned straight ahead on a collision path, the patrol speed estimate would be close enough. But the further the object is located off a direct line to the target, the lower will be the estimate of patrol speed. This is a simple trigonometry problem relating to the cosine of the angle between the target and the ground reflector, hence the name Cosine error. Since Cosine error always makes patrol speed seem smaller than it actually is, it always acts to raise the reading of target speed.

I don't think that I'm following your logic on Cosine error. If two vehicles are travelling at an angle to each other, then the direct line apparent speed differential of the two vehicles will always calculate as lower than the ACTUAL speed of the vehicles. The difference in distance, per unit time, will always result in a smaller number.

[spankayf]

I didnt write this although I did edit to make it clearer.

You are right cosine error between the 2 cars will also reduce the calculated speed so it all depends on the angles whether the net result is in favour of the driver or not. It's probably more of an issue with K band radar since the beam is larger than Ka and is more likely to reflect off other targets.

The scary thing about moving radar is there alot happening all at once and the curve in the road just increases the chances of error .... and the cop has to drive the car and verify the target which may be why the he didnt get a ticket in the incident.