Validity of Guys of Lidar off axis test

[mswlogo]

I was looking guys of lidar's off axis test.

First off I love these guys and their passion.

But is the off axis test really valid/useful?

When I hear references to off axis detection I think of how far the leo might be off the .side of the road. Or the road comes around a bend.

But to do the testing they rotated the detector.

Rotating the receiver is not the same as moving the source off axis.

It may be useful and the results may correlate but I don't it's the same as real world off axis encounters.

[Z1NONLY]

I was looking guys of lidar's off axis test.

First off I love these guys and their passion.

But is the off axis test really valid/useful?

When I hear references to off axis detection I think of how far the leo might be off the .side of the road. Or the road comes around a bend.

But to do the testing they rotated the detector.

Rotating the receiver is not the same as moving the source off axis.

It may be useful and the results may correlate but I don't it's the same as real world off axis encounters.

They used the foam to weaken the source signal and rotated the RD's because that was the best way to get consistent results.

(with the same weak signal coming at all the detectors, just at different angles.)

If they had altered the sources' location or point of aim, or the RD's location, then a lot of other variables would have been in play. (reflections would be a big concern)

[CJR238]

I was looking guys of lidar's off axis test.

First off I love these guys and their passion.

But is the off axis test really valid/useful?

When I hear references to off axis detection I think of how far the leo might be off the .side of the road. Or the road comes around a bend.

But to do the testing they rotated the detector.

Rotating the receiver is not the same as moving the source off axis.

It may be useful and the results may correlate but I don't it's the same as real world off axis encounters.

Though my simple answer would be YES the off axis test is useful for a reference. The parameters they used wont rely give a definitive answer, I too have the opinion that Rotating the receiver is not the same as moving the source off axis. Its as close as they could get to real world off axis encounter without several locations to test and additional $$$.


But there test is also a very good reference if alerting to off axis falses are important to you.

[jerry540i]

i was looking guys of lidar's off axis test.

First off i love these guys and their passion.

but is the off axis test really valid/useful?

>>the more we know about detectors the better. This test showed the various antenna design strengths/weaknessess on the horizontal plane.

when i hear references to off axis detection i think of how far the leo might be off the .side of the road. Or the road comes around a bend.

but to do the testing they rotated the detector.

rotating the receiver is not the same as moving the source off axis.

>>its exactly the same. Whether the radar gun is 30 deg. Off center or the detector is rotated 30 deg. From the radar source should yield the same results.

it may be useful and the results may correlate but i don't it's the same as real world off axis encounters.

>>no one ever claimed this was a real world test. As always, we welcome others to test and publish their own real world results if they don't like/believe our results.

j/

[snoopyc4]

I was waiting for a GOL member to reply to this thread. Foam might not be used in the real world but off axis radar is used.

[jimbonzzz]

The resoning behind the test is simple, yet the concepts are very difficult for many people to grasp.

The detector's antenna has a pattern, but the radar gun itself has it's own antenna pattern. If one were to test the way we did, but instead keep the detectors fixed and rotate the radar gun, this would basically expose the detector's front lobe to the radar gun's changing antenna pattern as it is rotated at the different angles. So instead of testing the "off-axis" receive capabilities of the detectors, this would, in effect, be testing the antenna pattern of the of radar guns. This isn't what we wanted to do. Although this might be something interesting to do, perhaps to compare differences between several different models of radar guns, testing the radar guns was not the intent of our test.

The purpose of our test was to test the receive capabilities of the radar detectors. The only solution was to keep the radar on a fixed mount as a control, and instead rotate the detectors. The way, our test ensured that each detector was exposed to the exact same beam intensity at each angle, the only thing that changed from run to run was the angle of the detector in relation to the radar. By testing this way, the off-axis receive capabilities of the detectors could be determined and compared.

Ultimately, by testing the way we did, we were able to do a very crude plot of the detector's antenna patterns without costly lab equipment. How the detector's capabilities compared to one another was very clear, and these capabilities translate directly to the real-world.

[hockey005]

professors brain > yours

[CJR238]

The resoning behind the test is simple, yet the concepts are very difficult for many people to grasp.

The detector's antenna has a pattern, but the radar gun itself has it's own antenna pattern. If one were to test the way we did, but instead keep the detectors fixed and rotate the radar gun, this would basically expose the detector's front lobe to the radar gun's changing antenna pattern as it is rotated at the different angles. So instead of testing the "off-axis" receive capabilities of the detectors, this would, in effect, be testing the antenna pattern of the of radar guns. This isn't what we wanted to do. Although this might be something interesting to do, perhaps to compare differences between several different models of radar guns, testing the radar guns was not the intent of our test.

Ok lets spin this a bit.

The detector's antenna has a pattern, but the radar gun itself has it's own antenna pattern. If one were to test the way you did, but instead keep the radar gun fixed and rotate the detectors, this would basically expose the RD's front lobe to the radar guns changing antenna pattern as it is rotated at the different angles, just like it would in real life. Thus representing exactly how it would be in the real world with that specific gun.

Reason i spun this is the simple logic "i don’t run with my RD at an angle" so how can this make sense. Though it may not represent real world results or even how the RD would react with that particular gun in real life it gives a good ideaat least i guess with some consistency.

[thx1138]

The test accurately exposes differences in off axis between radar detectors. Real world is probably much more pronounced due to the combination of the RD off axis and the radar gun's off axis antenna performance.

If you are coming round a curve and about to drive into a radar beam (especially an instant on hit), off axis becomes pretty important. Your RD is essentially at an angle to the souce, even though from your perspective its pointed straight ahead.

[mswlogo]

The resoning behind the test is simple, yet the concepts are very difficult for many people to grasp.

The detector's antenna has a pattern, but the radar gun itself has it's own antenna pattern. If one were to test the way we did, but instead keep the detectors fixed and rotate the radar gun, this would basically expose the detector's front lobe to the radar gun's changing antenna pattern as it is rotated at the different angles. So instead of testing the "off-axis" receive capabilities of the detectors, this would, in effect, be testing the antenna pattern of the of radar guns. This isn't what we wanted to do. Although this might be something interesting to do, perhaps to compare differences between several different models of radar guns, testing the radar guns was not the intent of our test.

The purpose of our test was to test the receive capabilities of the radar detectors. The only solution was to keep the radar on a fixed mount as a control, and instead rotate the detectors. The way, our test ensured that each detector was exposed to the exact same beam intensity at each angle, the only thing that changed from run to run was the angle of the detector in relation to the radar. By testing this way, the off-axis receive capabilities of the detectors could be determined and compared.

Ultimately, by testing the way we did, we were able to do a very crude plot of the detector's antenna patterns without costly lab equipment. How the detector's capabilities compared to one another was very clear, and these capabilities translate directly to the real-world.

Thanks

I agree and that makes sense but don't we want to know how the detectors behavor against different parts of the radar guns pattern (different amounts of the LEO being angled off the road)? Isn't that a more real world situation than the car going down the road at angle?

Perhaps your test more simulated a curve vs a Leo off to the side on a straight road.