Guys of LIDAR August Radar Detector Test - Results UP!

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10-30-2007, 08:40 PM
MEM-TEK

Quote:

Originally Posted by thestaton

oh man I've been waiting for this forever!!!

http://homepage.mac.com/thestaton/pi...lies/jerry.gif

Now on a serious note, I stand behind the forward facing tests and if I had the chance to do it again I wouldn't change a thing.

The test car never changed, nor did the car with the radar unit inside of it. So the variables stayed the same.

**********

EDIT: I was confused and was actually thinking and writing about the straight line sensitivity tests rather than the forward facing tests. Personally, I thought that the forward facing tests fairly well match the real world environment where I live in Georgia. Please substitute "straight line sensitivity tests" wherever I wrote "forward facing tests" in my comments below. Hopefully then my comments will make sense!

**********

Hi thestation,

Don't get me wrong! I totally agree that the forward facing tests were extremely well executed and do present actual real world expectations for how each radar detector, when mounted roughly low to mid level on the average car windshield, will perform. Why? Because each radar detector, depending on its inherent upward or downward flared horn design, was either more efficient or less efficient at picking up additional radar reflections off of the test vehicle's hood, and because scatter from real police radar does reflect off of the police vehicle's hood and off of the ground significantly ahead of it. Thus GOL's straight line tests do accurately represent real world straight line performance expectations based on each radar detector's horn design and upon a roughly low to mid level windshield mounting location..

I was merely trying to suggest a modified test setup which would eliminate each radar detector's ability to see any additional reflections off of either vehicle's hood or off the ground in order to get results which would very closely match the raw sensitivities as measured in a lab where great care is generally taken to only allow a radar detector to see just the actual radar beam and not any additional reflections from within the lab. Thus, my test setup ideas merely reflected my desire to accurately measure each radar detector's inherent sensitivity by not allowing any radar detector to gain any benefit of additional radar reflections from the car's hood or from the ground. Obviously a downward flared horn will allow a radar detector to more efficiently detect additional radar reflected off of the vehicle's hood and ground ahead of the vehicle. Yet a radar detector with an upward flared horn can always be pointed somewhat downwards to allow it to more efficiently pick up additional reflections off of the vehicle's hood and thereby boost its sensitivity by about 2dBm.

Nevertheless, I am most pleased with the consistency of my calculated dBm sensitivities based on GOL's straight line tests versus Michael B's lab measured sensitivities. My calculated results mostly agree with Michaal B's lab measured results to within +/-2dBm or better, and this says volumes for how careful GOL was when performing the August straight line sensitivity tests. This high degree of correlation would have not been possible if the GOL straight line tests were significantly flawed in any way. In other words, GOL's August straight line sensitivity tests do represent real world usage conditions, and I consider the results to be carved in stone. :D
10-30-2007, 09:23 PM
MEM-TEK

Quote:

Originally Posted by Azonehits

Quote:

Originally Posted by MEM-TEK

On the other hand, I do think that reflections off of the hoods of the radar vehicle, the radar detector vehicle, and the pavement between the vehicles did slightly affect the tests since some radar horns flare downward whereas other radar horns flare upward.

This will not reflect radar signals back but rather forward and does not make any difference at all. I don't understand why the pavement between the vehicles will make a difference regardless of the flared horns. What makes a difference with forward facing tests is reflection or bounced signal that's suppose to go forward but bounces back because of objects in front of the radar gun. Without this reflections, the distance detected by the RD will be shorter. Even if it bounces from the hood, the radar don't reflect back but rather forward unless the front part of the hood is bent 90 degrees.

Ecosorb was used around the radar antenna to decrease strength of radar intensity and without blocking the front of the PVC pipe even if it was lined with ecosorb, you're talking about miles of testing from point A to point B. In your suggestion, you will still have some amount of reflected signal when objects are in front of a radar gun.

**********

EDIT: I've been talking about the straight line sensitivity tests rather than the forward facing tests. I was tired and confused. Sorry for the confusion I caused! Below, I am talking about the straight line sensitivity tests. Nevertheless, I think that my example of a downward flared versus an upward flared radar horn do have merit.

**********

No, I am still assuming that Eccosorb would still be used at the front (or back) of the PVC pipe to attenuate the signal to shorten the short test course. I also mentioned that any reflections off of the vehicle hoods and off of the ground only slightly affected the test results. I should add that GOL's test setup does rather accurately reflect real world conditions. I was more interested in the inherent sensitivity of each radar detector without allowing each radar detector to gain any benefit, due to its either upward or downward flared horn design, by also detecting additional reflections off of the vehicle hoods or off of the ground between the two vehicles.

I've created some drawings to illustrate the things which I talked about:

http://www.mem-tek.com/radar/radar_h...eflections.gif
In the above drawing, it should be obvious that the more sensitive radar detectors will detect the radar gun much further away and that the more sensitive radar detectors will also be picking up very weak radar reflections off of the pavement. It should also be obvious that less sensitive radar detectors will pick up the radar gun only when they are much closer to the radar gun. Yet, when much closer to the radar gun, the somewhat shielded radar gun's signal may not have diverged downward enough to also reflect off of the ground and thence towards the closer and less sensitive radar detector. Truthfully, I wouldn't expect these scenarios to greatly or even moderately skew GOL's distance measurements. Like I said, I would only expect that the lack of ground reflections when close to the radar gun would only very slightly affect the test results since any ground reflections are quite weak. Regardless, I do enjoy thinking about every possible variable within any testing methodology.

http://www.mem-tek.com/radar/radar_h...lared_horn.gif
This drawing shows how a radar detector with a downward flared radar horn is relatively efficient at seeing additional radar reflections off of the car's hood and off of the ground in front of the car. Note that the ray traced dark orange radar paths undergo very few internal bounces within the downward flared radar horn in order to reach the back of the radar horn where the detection circuitry is located.

http://www.mem-tek.com/radar/radar_h...lared_horn.gif
This drawing shows how a radar detector with an upward flared radar horn is less efficient at seeing additional radar reflections off of the car's hood and off of the ground in front of the car. Note that only the dark orange ray traced path entering at the bottom of the horn reaches the rear of the radar horn without undergoing numerous internal reflections. Now note that the other two dark orange paths undergo multiple reflections within the radar horn and that these reflections steadily increase in angle due to the upward flared radar horn. Finally, note that any radar detector with an upward flared radar horn can be pointed downward to essentially make the horn have a downward flare, allowing a radar detector with an upward flared horn to be much more efficient at additionally detecting radar reflected off of the vehicle's hood and the ground ahead of it.

I wasn't trying to stir up a hornet's nest! I was simply trying to bring up some ideas which I have been thinking about. :)

--Michael
10-31-2007, 01:18 AM
KnightHawk

Quote:

Originally Posted by MEM-TEK

I was more interested in the inherent sensitivity of each radar detector without allowing each radar detector to gain any benefit, due to its either upward or downward flared horn design, by also detecting additional reflections off of the vehicle hoods or off of the ground between the two vehicles.

I've created some drawings to illustrate the things which I talked about:

http://www.mem-tek.com/radar/radar_h...eflections.gif
In the above drawing, it should be obvious that the more sensitive radar detectors will detect the radar gun much further away and that the more sensitive radar detectors will also be picking up very weak radar reflections off of the pavement.

--Michael

How could this be possible when the radar detector is behind the radar gun in the forward facing test? Plus, you are not just looking at vertical axis bounce but rather a mix of vertical and horizontal bounce which can come from many directions. Think of a circle in front of you since all if not most radar guns have circular antenna's. Imagine how that circle can translate to hundreds of thousands of dots that can scatter as distance increases when it bounces from an object.

Even if the radar and the radar detector are face to face with each other, have you ever considered the direct line of sight at which the radar detector receives its signal without the reflected or bounced signal from the pavement or hood? Which would you think would travel faster, bounce or reflected signal vs. direct line of sight or straight line? It just makes sense that direct line of sight travels faster than reflected signal.

BTW, i believe there was no ecosorb used during the forward facing test in the Arizona and Ohio test site. Correct me GOL if i'm wrong on this one.
10-31-2007, 05:53 AM
thestaton

correct. for forward facing you pretty much can't use eccosorb. if the detector even alerted it wouldn't be but around 25 feet.

kind of like cobra on regular tests :)
10-31-2007, 09:01 AM
MEM-TEK

Hi guys,

I've been confusing the straight line sensitivity tests with the completely separate forward facing tests. Yesterday was a hard day at work, and I was tired when I wrote my posts. My apologies for the confusion I caused.

Please realize that I was thinking and talking about the straight line sensitivity tests even though I mentioned "forward facing". Perhaps then my posts will then make sense. I will edit them, changing "forward facing" to "straight line sensitivity". Again, my apologies for the confusion my posts caused. It must have looked like I was really off my rocker! :lol:

--Michael
10-31-2007, 09:10 AM
thestaton

it's all good. we all have those days.
10-31-2007, 09:31 AM
happya$$

Since the Professor is not responding to Mem-Tek's posts I am assuming that Mem-Tek has been technically right on on his last few hundred posts :lol:
10-31-2007, 09:44 AM
MEM-TEK

Quote:

Originally Posted by happya$$

Since the Professor is not responding to Mem-Tek's posts I am assuming that Mem-Tek has been technically right on on his last few hundred posts :lol:

I wish that were true! He has responded to a few of them and caught a few mistakes which I've made. Jimbonzzz is "The Professor" and his knowledge continues to blow me away. :D

I bet you all had thought that I had really lost it, due to my confusion regarding the forward facing tests and the straight line sensitivity tests. Its Halloween! Does anyone have some holiday related comments to describe how "batty" my posts must have seemed due to my confusion?

--Michael
10-31-2007, 10:03 AM
jimbonzzz

MEM-TEK: you are full of BS!
How's that, happy now? :wink: :lol:
10-31-2007, 10:19 AM
MEM-TEK

Quote:

Originally Posted by jimbonzzz

MEM-TEK: you are full of BS!
How's that, happy now? :wink: :lol:

Full of Headless Horseman happy horse sh#t would have been more Halloween like. :lol:

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