LIDAR: Lasers Nab Leadfoots
LIDAR (Light-Imaging Detection and Ranging) is the new generation replacement for the older Radar systems that police have been using to catch speeders. LIDAR uses an IR Pulsed Laser Diode to measure speed, distance and direction. By using beam width of less than one-degree, it’s significantly more accurate than the older radar systems. As the beam crosses the traffic lanes, it can also target a single vehicle at a time and minimize the possibility of false readings.
When the LIDAR instrument transmits light out to a target, the transmitted light interacts with and is changed by the target. Some of this light is reflected back to the instrument where it is analyzed in a fraction of a second. The time for the light to travel out to the target and back to the LIDAR device is used to determine the range to the target. LIDAR guns fire multiple pulses of light each time a police officer pulls the trigger. By measuring the difference of the reflected light pulses, LIDAR guns are then able to determine the traveling speed of their target. Watch out all you lead foots!
You may watch the LIDAR: Lasers Nab Leadfoots TV story online.
Video Games for All and Underwater Flight (episode #109), in which LIDAR: Lasers Nab Leadfoots is a short story, airs tonight on QUEST at 7:30pm on KQED 9, and KQED HD, Comcast 709. (full schedule)
Chris Bauer is a Segment Producer for television on QUEST, and is the producer for this story.
15 Comments
Speed the main culprit ? The greatest brainwashing propaganda since the invention of wheel !
Unrealistic speed limits do not work toward safety , instead in the long run , people will see those tools ,laser , as a mockery of safety and fast easy money machine .
Loud music , eating ,cell phone , inattention , fatigue, zigzaguing … all factors not taken in the equation …
Who cares for a true road safety ?
While I liked the program, there are many inaccuracies in the piece.
LIDAR divergence (spread) IS similar to radar, just not as wide. One officer is mistaken about THIS fact and mis-spoke.
To have an officer claim its "pin point" (a marketing "claim") vs radar, means he fully doesn't understand the concept of a beam that spreads as it gets farther away from the "Stacked" laser Diode array. Then again, LTI never mentions how wide the beam(s) actually are at reference distances either. They mention ~3 milliradians and equate this to 3′ wide @1,000 feet. Most operators are clueless to this fact that 3′ wide isn't "pin point".
The dot in the HUD (Heads up display) of the Marksman only shows speed unless the "range" button is QUICKLY toggled back and forth. QUICKLY, I say, because the ~10 year old LIDAR he uses is the same one I have and its info in the HUD is only viewable for 2-3 seconds.
The Marksman really limits the feedback to the operator WRT: the crucial data needed in real time to determine IF the vehicle clocked is actually the vehicle (or surface) aimed at. Just having the speed displayed in the HUD isn't all the info the operator needs to know to make a positive determination that the info returned, is indeed the targeted vehicle's speed. The distance should also be shown as it is in a Stalker LIDAR HUD for instance……
The HUD "dot" isn't representative of the actual beam of the LIDAR beyond ~150 feet. Considering that its also not in line with the Transmitting lens, there is an additional parallelax error introduced between the site aim and the actual Tx lens of the LIDAR.
Next, the LTI comes with a shoulder stock for steady aiming. A requirement in the operators manual. Considering that department spent the extra $1000 for the HUD option, these officers choose NOT to use the stocks to steady their aim, which leads to many operator errors in aiming, like panning an sweeping of the intended targets.
The voice over person incorrectly states how many pulses of reflected / refracted light are made by the gun; for a reading and each second.
Most LTI Marksman LIDAR guns produce 125 pulses per second. The gun CAN calculate speed using less than 1/3 of them in perfect test conditions.
The gun does so roughly in THIS "approximate" way:
A few pulses are sent and hopefully received back.
Of these first few pulses, they are compared to each other to see if the target vehicle / item is moving.
Then the next series of ~40 or more pulses are examined to see if the return values, when applied to a line (by the method of least squares) can calculate a speed. I say calculate (through an algorithm LTI won't disclose) because all a LIDAR gun can do is measure distances over time…..
Its these 40 or more returns which are used to attempt to calculate a speed. If there are 125 pulses per second, the 1/3 of a second means that
at least 40 plus pulses are needed to obtain a calculated "speed" reading.
LTI claims a reading can be obtained in 1/3 of a second. The MArksman is actually very quick in its target acquisition, but its accuracy lies in the fundamental flaw of simple LIDAR against moving, sloped shapes and the ability of the operator to precisely operate the LIDAR gun accurately.
LTI boasts that each space shuttle uses their LIDAR guns to determine distances in space, but most spacecraft have large, mostly flat surfaces which reflect LIDAR beams back very well. Not quite an apples to apples comparison to vehicle traffic, now is it?
Accurate aim is to induce panning and actually focus on one "point" of a vehicle and pan/move along with that same point the entire time the reading is being calculated. Most *think* they can accomplish this (these officers without using a shoulder stock) but, consider the moving target "in a perfect scenario" moving 60 MPH (88 feet per second) the operator will have to of moved along with THAT point on the vehicle ~29 feet in 1/3 of a second. No small feat.
There are a few other points I'll think of later on, and for those reading, my descriptions are a ballpark of the operation of the LIDAR gun shown in this TV piece.
Lastly, I can't believe a 2007 TV show features LIDAR guns from cicra: 1997 either.
-Suf Daddy
Two quick points:
The TV show simulated the HUD info display. It is NOT an actual LTI MArksman HUD display reading.
The "speed" reading value (if selected) blinks for about 2-3 seconds then disappears. IF you select "range" you get distance info only, its one or the other, causing the operator to not have one of the two info bits (Speed & Distance) available during sighting of the target vehicle.
The Officers are shooting cars mid corner (in a curve) opening the entire side of a vehicle to the pan and sweep effects of the LIDAR beam reflecting back to the Rx (Receiving) lens. Usually, when aimed dead ahead, the slope of the hood, windshield and roofline come into play, here the officers choice of location, for surprise, introduces an additional influence which could either add or subtract from the vehicles calculated speed readings determined by the LIDAR gun…..IMHO poor location choice.
Since the LIDAR beam is invisible to the operator and motorists, who knows if the HUD dot is actually properly aimed? Some of the aim calibration test wouldn't actually pick up a mis aligned instrument if careful consideration wasn't
given to rule out a HUD dot misalignment……..
-Suf Daddy
Disappointing, Suf Daddy hits the points dead on.
At the end of the day, LIDAR is still more accurate than RADAR. RADAR requires the operator to discern which vehicle is travelling the fastest. LIDAR, with a beam that is only 3 feet wide at 1000 feet distant is much more exact. Sure it may not be a "pin point" but it is much more exact than RADAR.
Further, parts of the LIDAR beam that are reflected by curved surfaces of a car never return to the gun, they get reflected off elsewhere. So, only the pulses that return to the gun are analyzed. That is why LIDAR and RADAR work.
Moreover, police, who are prudent, test their equipment before they use it, every time. Testing the calibration for speed readings is vital to citations holding up in court.
While I admit that "bumper pacing" with a calibrated and certified spedometer is still the most accurate way for police to catch speeders, using devices like LIDAR and RADAR guns help a lot. Especially on narrow city streets with traffic that would hinder attempts to "bumper pace."
It is safe to say that this blog is simply a gaggle of people who are bitter that they got caught speeding. Sorry guys. As much as you think you can debunk RADAR or LIDAR, you can't. You should think about slowing down instead.
One last thing, you guys act like you've uncovered some super secret conspiracy to use faulty equipment to entrap innocent people. RADAR and LIDAR are not monumental frauds being perpetrated on the American people. Quite on the contrary, they are necessary parts of traffic safety.
Be thankful that you live in California and not other states like Maryland where speed enforcement is done with automated cameras, like red light cameras around here.
At the point you are punished for not operating within the guidlines, why not take free will out of the equation. Install speed limiters on vehicles, no vehice can exceed 65. People will still drive too fast for conditions, but accident impact speeds will partially be reduced. If we were truly concerned with safety this would be a likely outcome.
Speed laws only serve to generate revenue. People will continue to speed as long as they have the ability too. Laws only effect those that choose to abide by them.
Safety would better be served through attention to intentionally distracted drivers. Ticket those that talk on cell phones, put on make up, listen to music too loudly, etc… Speed is not the main culprit, it is just one of many. But, it is an easy act to identify, target and ticket.
You are free to act as you will, but be mindful of the consequences.
I am interested in anyone that has a reputable source of information regarding the faulty nature of the LIDAR (a journal reference or research paper). I recently was victimized by the "Accurate" LIDAR system. I was locked into going 65 MPH in Cruise Control on 680 in a brand new-paper plates still car and was pulled over and told the LIDAR clocked me at a ludicrous 90 MPH (from 1815 feet away)! Being that I was locked into 65 on my cruise control and that I have never driven 90 MPH in my life, I am out to prove that there can be serious, wide ranging error in this method. I am a scientist and would love to present findings on the LIDAR system in a scholarly manner to help myself and others prove the strong window of doubt cast among some LIDAR readings.
I also was ticketed on 680 just north of 580 interchange about 4 miles. I had my cruise set at 68 and with the slight downhill run was possibly doing 71/72. I also have never driven faster than 75 (Arizona) and think something else is causing serious misreads of their lidar. I also noted a vehicle passing me about 30 seconds before I saw the CHP in my rear view mirror, I wonder about target acquisition and mistaken plate reads?
For further info please see http://www.geocities.com/stop_abuse/LTI2020/OpinionE.htm
I had LIDAR touting cop walking 15 to 20 feet while taking speed check.
With that kinda handling,I'm sure the court walls will be closing in at 25MPH (J)
I'll appeal the lower court decision.
To my educated guess,the cheap looking silver plastic gizmo, which I was shot at might be in donation to cops from insurance company.
It is safe to say, each equipment pays its cost in first two traffic tickets to donor insurance company.
I guess that people that do obey the law or travel at a safe speed will get pissed off when they get convicted of something they do not do.
Errors happen. Unfortunately the court system is not on your side with traffic tickets. I have been a victim of a bad ticket and know what speed I was travelling. The lidar was a Marksman 20/20. I am not thinking that it was the guns issue but rather the way that the lidar reading was taken. The officer is sitting on the mid way point of an on ramp that is 280 degrees. Hardly a safe location for anyone. Traffic coming off the highway impedes the vision and the reason for being tucked in I suppose is to be hidden behind a cluster of trees. I do see a car passing me at a high speed and I figure the police officer is going after this individual. Further the officer is sitting in his car shooting through glass at a 45 degree or more angle. If someone is trying to tell me that there is no impact from the refractive index of glass shooting at these angles I think it is an easy fact to prove. In any event what pissed me off was not only that I was caught for something I did not do .. but the guy speeding also got away. Traffic coming onto the ramp also impedes the vision of the officer at the oncoming traffic and at that angle also the windshield cowl. So I get a ticket for going one kilometer over the new law limit of 50 km over. Lose my vehicle for a week, no income for a week. The manufacturer LTI states that the device is accurate within 2 MPH. So far 7 days in court. 2 Days in meetings and another 3 days in court to look forward to in the future. Plus appeal time. Now since this law takes your rights away immediately there is pressure applied to crown attorneys and the police officers to not negotiate reason as this could result in people suing them for their loss of income and the towing and storage charges that added up to a hefty 500.00. I am actually all for this law if the devices are used properly to eliminate error. But this sloppy lack of training on the how to properly use the lidar is going to change peoples lives. There is 10000 fine that can be levied, and possible jail time.
The system as I witnessed so far is that you have to go to pay a an ex police officer to negotiate the fine down. Of course they have all been told that there is a directive that you can only go down so far and if you are already at exactly 50 km over well you are out of luck as they do not want to have repercussions over what moneys you already have paid out. After seeing the system in action it is amazing that these laws that clearly violate Canadians rights and remedies under the simply Charter of Rights. In any event for those that say just dont speed,, you really need to be convicted of lose all your rights falsely before opening your yap. Mistakes do happen. The simple rule of law is thrown out the window and flushed down the toilet. In this area they also do not calibrate their equipment. Doing a test on a static object from the parking lot is a partial test. If you go to the manufacturer and say you want the piece tested they do not do the self test on the unit. The mistake made in my situation was likely that from the angle of the laser through the side window actually picked up the other car that was speeding. The car that was speeding did look similar to mine. By the time the officer came up to behind my vehicle the other one was over the next hill and gone. I did not pass one vehicle from the time the officer came into view. At three occasions my car would have been out of view from obstructions on cars coming off the highway going on the off ramp.. and again twice as cars were passing the officers vehicle on the on ramp.
Zapped and Mary, you both state similar circumstances to mine, Mary being on the same Interstate and general location. Zapped your citation was problably the same as the guy who passed me at about 85 mph (kph ?),I thought for sure the CHP had him in his sights so much so that I moved out of his way to clear the lane so he could try and catch the speeding driver only to have him use lights to pull me over. My day in court comes the 24 th. All I have to stand on is 40+ years with no citations and over 32 years of commercial driving and 2M miles NHTSA Safe Driver Award. My best advice is find all the details and FIGHT BACK!
Apart from the technical accuracy of these devices, the use of them as revenue collection tools seem to be another fault of the justice system. Park Ave near downtown San Jose is a simple 2 lane street with a mix of residential and small retail businesses. The street is posted at 30 MPH. The exception to this description is a section of about 1500 feet when the road widens to 4 lanes, has a concrete divider between the directions and takes a deep dip as it passes under the train tracts. The SJPD officer stood near the top of the ascending grade and aiming at the bottom of this underpass. At the bottom of the underpass, the vehicles have just picked up speed from the descent and would be at their fastest rate. Typically they would lose speed as the ascent up the other side, but by that time the LIDAR has caught them at the bottom, at their maximum speed, where the roadway is well divided, there is no cross traffic, not even a driveway Still the SJPD has used this exact location to enforce a speed limit intended for the 2 lane residential sections.
In preparing my defense, I went back to the location, took photos, made measurements, and clocked a number of vehicles through a section I marked at the bottom of the underpass. Hardly any vehicle I measure was going under 50 MPH at the bottom, but virtually all of them were back down to the typical speed of about 35 by the time they has reach the surface level and the first intersection on the top side.
This was clearly "easy pick'ins" for the SJPD. It would likely have been found illegal if the proper traffic survey has been done in that exact location. While I had fully prepared my case for court, the office didn't show up as he had some training that day, and the judge dismissed the case. While I was not unhappy about having gotten out of the ticket, I was a little disappointed that I didn't really get the trial to introduce the facts on their merits.
I had had a previous experience where the CHP were running a radar gun on east bound Montigue Expressway. They were measuring the speed just as I came over the overpass at the railroad tracks and Lafayette in Santa Clara. I was riding my motorcycle and had used enough throttle to climb the ascending grade. AS the bike reached the top of the pass, it began to pick up speed and naturally I backed off the throttle, but not before I was "gunned" for doing 60 in a 50 MPH zone. The conditions at the point I was measured were identical to any freeway, including the on ramp past the bottom of the grade. The roadway was widely divided, 6 lanes with breakdown lanes on the sides, warm summer day – bright and dry roadway and no obstacles, adjacent vehicles or pedestrians to constitute any hazard in that section. The officer explained that children use the sidewalk further along and that was the justification for enforcing speed at that point. Yet, the CHP choose the easy place to give tickets, not the place that constituted the greatest hazard, just 1000 feet further along. Before I even saw them hiding in the trees, I was back to 50 MPH and not yet at the bottom of the overpass.
At the time I was preparing my LIDAR case, I had counted the number of elementary schools within the SJPD's jurisdiction, yet they has taken their only LIDAR device to an underpass, and this was a frequent location for them to set up shop.
I see this a lot in driving around – the police hiding in easy to catch places like the newly finished Pigeon Pass out of Livermore with it's 4 lanes, picking people off right and left by teams.
It's OK to use these tools of enforcement where real hazards exist, but to turn them into revenue machines is just a perversion of justice!
I have an appeal coming up in Placer County about a LIDAR ticket. After researching, I do not find that the technology meets the Frye standard which governs the use of novel technology such as LIDAR. I have read several cases in other states where LIDAR was thrown out due to its novel science and the fact, like in CA, there is no single court case where there was expert testimony to set the precedence for judicial notice that LIDAR is in fact scientifically accurrate. In order for courts to take judicial notice, they must have one case where this sets the stage for others to recognize.