Off access radar Tec question

[CJR238]

From what I have herd your actual speed is lower on off access (non direct) radar encounters?

If you get an off access radar K or KA what would be the difference in speed according to the angle of the LEO in relation to you?
Ex:
Striate on he reads 55 and your speed is 55.
At a 35% angle from road and he reads 40 and your speed is 55?
At an 80% angle from road and he reads 20 and your speed is 55?

Is the above guess somewhere in the realm of reality? Can someone shine some more light/detail on the subject?

[bart99gt]

Cosine effect isn't linear, but generally speaking there needs to be more than a 30 degree angle between the LOS of the radar and your vehicle before it really starts getting significant (ie., more than a 2-3 mph difference).

Look at this link, and scroll down to page 12. It has a table illustrating cosine effect.

http://www.fightghs.com/GHS/document...dar_Manual.pdf

[CJR238]

From what I have herd your actual speed is lower on off access (non direct) radar encounters?

If you get an off access radar K or KA what would be the difference in speed according to the angle of the LEO in relation to you?
Ex:
Striate on he reads 55 and your speed is 55.
At a 35% angle from road and he reads 40 and your speed is 55?
At an 80% angle from road and he reads 20 and your speed is 55?

Is the above guess somewhere in the realm of reality? Can someone shine some more light/detail on the subject?

Sweet! That’s what I was looking for.
Why do I se Leo’s at 30-40 degrees off access? Seems like a waist of time unless they can just add speed to what they are reading (sounds illegal).

2nd question:
On a striate road with good detection by both parties’ how much further will a RD pick up the LEO before he gets your speed, K & KA?

[TQUILL]

Sweet! That’s what I was looking for.
Why do I se Leo’s at 30-40 degrees off access? Seems like a waist of time unless they can just add speed to what they are reading (sounds illegal).

2nd question:
On a striate road with good detection by both parties’ how much further will a RD pick up the LEO before he gets your speed, K & KA?

First off I think you mean off axis. About your first question: The further you are away from the cop, the smaller your angle between your vector of travel and his position. Another explaination is perhaps he isn't working radar at the moment, even though it may be on.

I'm not sure about your second question.

[bart99gt]

Remember, cosine effect is always in the favor of the motorist. So if a cop is running radar or laser at a 30-40 degree angle (which I've never seen) you'd have to be going much faster than he's actually seeing to warrant his attention. If anything, the ticket you get would be less than what you were actually doing. So why complain?

[jdong]

Remember, cosine effect is always in the favor of the motorist. So if a cop is running radar or laser at a 30-40 degree angle (which I've never seen) you'd have to be going much faster than he's actually seeing to warrant his attention. If anything, the ticket you get would be less than what you were actually doing. So why complain?

The same, however, doesn't apply to moving radar

[bart99gt]

Remember, cosine effect is always in the favor of the motorist. So if a cop is running radar or laser at a 30-40 degree angle (which I've never seen) you'd have to be going much faster than he's actually seeing to warrant his attention. If anything, the ticket you get would be less than what you were actually doing. So why complain?

The same, however, doesn't apply to moving radar

Well, cosine error is NOT in the motorists' favor with moving radar if the antenna in the vehicle is pointed off axis. It will cause the patrol speed to read low and inflate the target speed. Again, we're only talking about a couple of miles per hour in most cases. Though I have seen some antennas mounted in patrol cars that were grossly mis-aimed.

Assuming that's not the case, cosine effect works just as it does with stationary radar.

[CJR238]

I have seen LEO's driving in the opposite direction on parkways turn around and go after people and there was about 2000ft of grass between the LEO and driver. I would think that’s at least a 30 degree angle.

[TQUILL]

I have seen LEO's driving in the opposite direction on parkways turn around and go after people and there was about 2000ft of grass between the LEO and driver. I would think that’s at least a 30 degree angle.

At 30 degrees with 2000 ft of grass between the driver and the point along the road the cop is perpindicular to, that means the cop is over 1150 feet away from the road (using simple pythagorean theorem). That seems unlikely. What could be happening is he that another officer is radaring somewhere else and the radaring LEO is talking with the other LEO on the radio telling him which cars to get.

With moving radar I believe it displays the calcuated speed of the patrol speed. A LEO would know if the reading would be off if the calculated patrol speed was different than his speedometer. If they were the same, then the cosine error would still work in the targeted car's favor.