Police radar, how does it work

[Bigsaint]

Max, I understand what your saying, but it seems to only be a very temporary fix at best. I'll give you an example. We have a problem with residents complaining about speeders in a community in our town. The road that goes directly through their crossing to access the beach area of the community is heavy with commuter traffic in the AM and PM hrs. The speed limit also decreases from 45 to 35 approx. 200 yds. before the ped. crossing, adding to the problem. Initially, we tried to run stationary radar in the area, wrote very few summons as most drivers were traveling between 35 and 40 mph. We knew this wasn't the typical speed through this area as the State had set up a speed/traffic monitoring system (you have probably seen them, black rubber lines streched across the road, can be used to either count traffic or count traffic and log vehicle speed). Some of the speeds recorded by the State's system were as high as 75-80 mph, while the average was somewhat above 50 mph.



When we ran the radar, the avg. speed was 30-35, but as soon as we left, the recorded speed went right back up to 50 mph +. The only way that we found that the speeding could be reduced consistantly was to issue summons, we even tried mostly verbal warnings to drivers stopped with moving radar, same results, as soon as we left the area, the speeds went back up considerably.



Human nature being what it is, seems that the majority take the visibility of the radar post or the warnings as a minor temporary set back, while the issued summons has more of a lasting immpression.



In all fairness, we have some areas that we can't seem to make a impact upon no matter what we do, could sit there all day and issue for speed, go back the next day, same time and place and do it all over again and again. Strange thing is that this one area that comes to mind is not a heavy commuter traffic area, but a problem with accidents due to the hidden driveways, etc.



I remember reading about a study that was done quite awhile ago in regards to motorists and and their typical reaction to viewing a patrol car, I believe that the conclusion was that most slow down for approx. the next several miles, then go back to thier original speed. Can't remember who did the study.



We tested this theory a few times, posting two cars in the same area, approx. 2 -3 miles apart, never had a problem finding speeders whether the first car was on a stop or just parked on the side of the road operating stationary radar.



Your theory on visibilty does seem to work if the area is constantly soaked with patrol vehicles, we have a large rural town and the areas that see us the least have the highest speeds, the roads that we frequently travel have much lower speeds for the most part. The community I mentioned above is at the fringe of our town, hardly ever sees a rountine patrol.



Scott W.

 

[Deezul1]

Amianthus, Bigsaint

You guys are on the money, I am more careful of speed limits now. I find that I am watching the speedo closer than before and boy do we have to poke along to comply sometimes. Prolly the only places I have been real watchful is school zones (hate to hit a kid) and strange towns when traveling, I guess I get familiar with the local roads and know the hazards and feel more comfortable going a little to fast.

You all are a great help

Thanks

John

 

[Max340]

Saint, your situation does seem to be frustrating at the very least, since it seems that both examples have reason for lower speeds. I recall some research done that claimed the road should have a posted limit in the 85th percentile of the traffic's speed. Obviously, with safety concerns such as a cross walk and driveways, this means nothing.



My general habit has been to run within 5 mph of the limit in town, and drive at a comfortable speed outside of town. I haven't altered this habit due to any enforcement action.



Flip side of the coin is, on my street, posted at 25mph, I have cars pass the house that I know are well over 35mph. Unfortunately, the local cops blew their enforcement when they placed the VASCAR stripes too close together, and someone took them to court specifically citing the distance factor. The Judge nailed them on it, and the enforcement on this street has been nil since then.



Its not a game that can be won, is it?

 

[Bigsaint]

Max, I agree. There really is no way to stop speeding or a persons propensity (sp) to speed. I stopped losing sleep over yet many years ago.



Scott W.

 

[Bill Lins]

Originally posted by Deezul 1

Thanks for all the input guys, keep it coming. Knowledge is power and I need it. If I had it coming I would just go to traffic school and be done with it but for once I am not guilty and will fight and hope with you alls help maybe win.

Can anybody from Texas tell me, can you still go to traffic school and keep it off your record if you lose in court?

Thanks

John

Generally, you must plead guilty- very few judges will let you fight the ticket and lose, and then cut you slack. Also, the ticket must be written for less than 25mph over the limit, and cannot be for a speed violation in a school or construction zone.

 

[Bigsaint]

Bill's reply brought to mind another good point... It's usually worth the trip to court to speak with the Prosecutor or the Officer, if the court does not use a Prosecutor for MV trials. It is common practice for the Prosecutor to downgrade speeders to the next lower bracket (15-20 MPH over gets downgraded to 10-14 over, 10-14 goes to 1-9,etc. ) in order to avoid trials and move the calender along. At least it is in our court. Most times, the Officer will not object to this practice. Here in NJ, it will save you points and lower or eliminate the insurance surcharge.



Scott W.

 

[Alan Reagan]

In Georgia, you can opt for school the first time and there is no fine, no points. Only works once though.



Also, Bill Lins made a good point on the cosine error. This is important if you are ever "clocked" on a curve either by a stationery or moving enforcement vehicle. The cosine error has been proven to be enough to drop most tickets when contested. Otherwise, doppler is very accurate.

 

[JohnMcIntyre]

Laser Cloaking device

Hey guys, I just came across a product here in the UK called an "SLD920 Laser Diffuser"; unfortunately can't find a weblink for it (yet). Apparently it's legal to buy and to use it here in England!! , not too sure about the lower 48 though... .



Essentially it's a stealth installation, which when turned on will audibly alert the driver to the presence of local laser frequencies and/or sources with a wavelength of 800-1100nanometers. Inside the vehicle, the only visible sign of the unit is a very discrete, simple on/off toggle switch and a small piezo audible alert beeper.



Installation looks fairly easy - a couple of laser transponder diffuser modules positioned at the front of the vehicle either side of the licence plate, parallel to the road surface and about 25 inches apart, set back from behind the front bumper with an unobstructed view of the road ahead... . very Dodge friendly!!



When its activated by a laser source, it somehow interferes with (aka diffuses) the laser beam, making nonsense out of any sort of returned value..... sounds too good to be true! It claims to have a 2 mile range and can detect ALL laser guns. Unfortunately, you'll have to say goodbye to Benjamin Franklin 4 times and conspicuously does not come with an FCC seal of approval



A TDR roadtest may be appropriate!

 

[Scooby]

Re: Laser Cloaking device

Originally posted by JohnMcIntyre

Hey guys, I just came across a product here in the UK called an "SLD920 Laser Diffuser"; unfortunately can't find a weblink for it (yet). Apparently it's legal to buy and to use it here in England!! , not too sure about the lower 48 though... .



Essentially it's a stealth installation, which when turned on will audibly alert the driver to the presence of local laser frequencies and/or sources in the range of 800-1100nanometers. Inside the vehicle, the only visible sign of the unit is a very discrete, simple on/off toggle switch and a small piezo audible alert beeper.



Installation looks fairly easy - a couple of laser transponder diffuser modules positioned at the front of the vehicle either side of the licence plate, parallel to the road surface and about 25 inches apart, set back from behind the front bumper with an unobstructed view of the road ahead... . very Dodge friendly!!



When its activated by a laser source, it somehow interferes with (aka diffuses) the laser beam, making nonsense out of any sort of returned value..... sounds too good to be true! It claims to have a 2 mile range and can detect ALL laser guns. Unfortunately, you'll have to say goodbye to Benjamin Franklin 4 times and conspicuously does not come with an FCC seal of approval



A TDR roadtest may be appropriate!

 

[Max340]

Originally posted by Alan Reagan

Also, Bill Lins made a good point on the cosine error. This is important if you are ever "clocked" on a curve either by a stationery or moving enforcement vehicle. The cosine error has been proven to be enough to drop most tickets when contested. Otherwise, doppler is very accurate.

Problem is, the cosine error favors the speeder by reporting a lower than actual MPH.

 

[Koa Man]

Re Laser Cloaking Device

John,

What you described sounds like the Blinder M10 laser jammer. The instructions for it tells you to install 25 inches apart. Let me assure you that it DOES work. I have had mine tested by a police friend and he could not get a reading and tried 5 times. Installation is fairly easy, except for trying to get the wires thru the firewall.



See my previous post in the early part of this thread and check out the website I have listed. Lots of good info there.

 

[JohnMcIntyre]

Detector Detector?

Originally posted by Koa Man

John,

Let me assure you that it DOES work. I have had mine tested by a police friend and he could not get a reading and tried 5 times.

Thanks Koa Man. One question I have is still unanswered. Given that it's a stealth unit and by definition it cannot be a passive device, how detectable would such a unit be to a Radar & Laser Detector Detector for instance.



JMc

 

[joel]

Cosine error

Not sure of the physics of cosine error (as in calculating the actual difference), but radar will report a lower speed if it's not getting a direct closing reading. I still think you could use that to your advantage because the officer who wrote the ticket cited you for the wrong speed (depending on the angle off, it's probably not off that much) but you could, in theory, make the argument that the officer and radar gun didn't know your speed and therefore, the ticket is invalid. The speed on it is not correct. Not sure if it would work... and if the judge asked you to do out the math and you had to show you were actually going faster than the reported speed... ... ...

 

[Alan Reagan]

Joel, you are correct. I did all of this in college and as soon as I find my physics book, I'll put the formulas out so that people can calculate it for da judge.



Never mind, Check out this link. Be sure and look at the section on cosine error (section 4) and the section on the courtroom (section 7). Good work on this one.



http://www.copradar.com/preview/content.html

 

[Briar Hopper]

The biggest issue for me remains the loss of freedom that results from excessive and overzealous speed limit enforcement. (I kept track for 2 months, recently, writing the numbers down)Those who do not have the misfortune of living in this state have no idea how bad it really is. Two years ago, our governor, a member of the liberal left, rammed a bill through the state house giving over $1 million a year to the state & local police agencies to be used for nothing but speed enforcement. not running stop lights, or drunk driving, just speed enforcement. Meanwhile, our vehicle property registration tax continues to be higher than most in the nation. It's not the cops, they're doing their job. It's the adminstration. We have a miniature version of the Clinton adminstration in this state.

Here is what I found, numbers wise:

I drive 50 miles a day, more or less, to town or city, or 2 counties away to work. In the 2 months I kept notes I saw:

2 state troopers in the same 12 mile stretch, everyday, REPEAT: EVERYDAY, (they'll be there tomorrow, too) same time. Moving radar, and I was targeted. On 4 occasions there was only one trooper.

I made 4 trips to the nearest sizable city, 4 days in a row, to work for a friend. 1st day: 6 city police cars, 4 with moving radar turned on, in 9 mile stretch. 2nd day : 4 cars, all with radar on.

3rd day: 4 cars, 2 with radar. 4th day: 8 cars, 5 with radar on.

Then, that Saturday night on the way home, on another road, counted 6 of those city police cars, all with radar on. I turned onto the interstate to finish my trip home, and counted 3 state police, radar on, two going my way, one opposite way, in a 10 mile stretch to my exit. That was 3 months ago. Today, that same stretch is a construction zone, double fines, so there are now(24 hours, round the clock) 5 city police cars at the county line, and an occasional state trooper just before the end of the zone. (clever, they plant the end zone signs more than a mile past where construction stops)

Draw your own conclusions. I have ! I don't vote for Democrats !

Sorry to make a political post, when the issue is technical, about devices... just my . 02.....