If you have received a citation for speeding in Santa Barbara or in neighboring Santa Maria, or Lompoc the likeliness of lidar or radar being used to determine your speed is highly probable. So what is the difference between lidar and radar?
The difference between standard radar and lidar (laser) is that radar systems use radio waves, and lidar uses narrow light pulses to gauge your speed.
WHAT IS LIDAR
LIDAR is an acronym for Light Detection and Ranging. Lidar guns (also known as “laser guns”), are handheld laser devices that law enforcement officers point at cars to measure their speed.
HOW DOES LIDAR WORK?
Lidar guns measure speed using a “time-in-flight” method. The gun shoots invisible, infrared laser beams at a rate of about 120 to 238 beams per second measuring the distance of the object during each of these 120 to 238 times per second (once for every beam). The Lidar gun measures the time required for each of beam to bounce back. The device then calculates the time “in flight” to produce the distance between the target and the gun. The gun tracks the change in distance during a given period of time and determines the target’s speed.
THE “LASER BEAM”
The laser beam- infrared light is about 18± inches wide at 500 feet up to about 22± inches wide at 1000 feet, typically .003% of the target’s distance. The greater the range, the larger the beam diameter, thus greater the difficulty of measuring just one target at a time.
WHAT’S THE MAXIMUM TARGETING RANGE OF POLICE LASER?
The range of a Lidar device can be well over two thousand feet (more than one-third a mile).
The functional range of a Lidar device (without out a tripod) is limited by the infrared beam’s width relative to the target’s size, the reflectivity of the target, atmospheric conditions, the cleanliness and age of the Lidar lens, whether the device is being directed through a windshield, and the operator’s ability to hold the device steady. Some laser guns have a distance range from 20 feet to 2000 feet plus.
Laser can be operated from very far distances, much further than police radar, making it extremely difficult for the driver to know that they are being targeted. Unlike with police radar, laser can be operated at such great distances, officers really don’t even have to hide like police radar operators, because it’s extremely hard to spot them from those extreme targeting distances. Some laser guns, manufacturers claim can successfully measure your speed as far away as 4000 feet or more, though generally targeting distances are below 2000 feet.
It is difficult for a law enforcement officer to continuously hold the beam on a moving vehicle that is further than nine hundred feet away. It is also difficult to identify a vehicle in daylight if it is further than eight hundred feet away. Most Lidar devices will not produce a measurement if a significant portion of the beam produces multiple distance readings simultaneously (i.e. half the beam is striking a car and half is over-shooting and striking an object behind the car).
For Lidar to work accurately, a certain percentage of the infrared beams emitted from the device must bounce back. If not enough beams return to the gun, the Lidar device will not produce a result. As such, police are generally trained to aim the beam at a car’s flat reflective surfaces, such as the license plate or headlights.
CAN POLICE LIDAR GUNS TAKE PICTURES FOR EVIDENCE AGAINST YOU?
Unfortunately, some guns do have the ability to take photos showing your vehicle and your speed, making it even more difficult to fight the speeding ticket in court, with the video evidence.
LIDAR SWEEP ERROR
Moving the Lidar beam during the measurement process may artificially increase the speed reading. Movement of the operator’s hand during the measurement process can cause erroneous speed measurements.
This is called “Sweep Error”.
When a police officer’s hand moves during the measurement process, the Lidar beam moves from one location to another. The difference in distance between the two locations may be read as if the device was measuring one moving object. The further the operator is from the target the more likely sweep error is to occur.
Another common sweep error occurs when an officer directs the beam at a vehicle’s windshield and then lowers the beam to the front license plate. The change in distance between the vehicle’s windshield and its front license plate may produce an increase in speed, or if the Lidar beam moves from one object to another the difference in distance between the two objects may be read as if they were one object moving.
This phenomenon can be observed by moving the Lidar beam quickly from the windshield to the front license plate of a parked car. The stationary vehicle will produce a speed reading of five to nine mph.
Yet another sweep error may occur shooting at hill or at a banking turn by sweeping the Lidar beam along the road surfaces. There have been reports that this sweep error has caused sweep errors of more than 90+ mph even without any vehicle being present. The faster the officers tracked the beam along the road the faster the reading on the Lidar device.
Without a proper tracking history an officer cannot rule out the possibility sweep error. Sweep error is more likely where the officer is only taking a quick “snap shot” speed measurement (i.e. taking a single speed measurement instead of continuously measuring the vehicle’s speed over a period of several seconds). Sweep error is also hard to prevent at great distances where it is hard to visually estimate speed and where even slight tremors in the hands can result in rapid changes in the location of the beam.
LIDAR SIGHT MISALIGNMENT
Most Lidar devices use a heads-up display (HUD) which contains a set of cross hairs and a digital screen which displays speed, distance, and approximate beam location.
As with any gun site, the HUD sites can become misaligned if dropped or mishandled. Misalignment may result in inaccurate aim. Simply, the officer measuring the wrong car.
To prevent sight misalignment, an officer should perform a vertical and horizontal sight alignment test at the beginning and end of each shift. This will guarantee that the sights were functioning properly during the traffic enforcement period.
The HUD on any Lidar device should never be magnified (most are not). This is because magnification makes the device more difficult to use at close ranges and distorts the officer’s ability to visually estimate the vehicle’s speed, an essential component of verifying that a Lidar device is functioning correctly.
California Vehicle Code 40802(c)(1)(D) requires radar, laser, or other electronic device used to measure the speed of the accused meet or exceeds the minimal operational standards of the National Traffic Highway Safety Administration, and has been calibrated within the three years prior to the date of the alleged violation by an independent certified laser or radar repair and testing, or calibration facility.
Additionally, at the beginning and end of each shift the officer should perform tests on their Lidar device. First the officer, should run a “self-diagnosis.” The officer should visually verify that all portions of the LCD screen are functioning and that the results of the self-diagnosis are positive. The officer should measure a known distance with the Lidar device and verify that it is working accurately. The officer should test the HUD to guarantee that the sites are properly aligned.
LIDAR OPERATOR CERTIFICATION
California Vehicle Code 40802(c)(1)(A) states: When radar is used, the arresting officer has successfully completed a radar operator course of not less than 24 hours on the use of police traffic radar, and the course was approved and certified by the Commission on Peace Officer Standards and Training (POST).
Radar (radio detection and ranging) units transmit radio waves at a designated frequency that reflect off of a moving target vehicle and return to the unit. The difference between the transmitted frequency and the return frequency is called the Doppler frequency or Doppler shift, which is used to determine the target vehicle’s speed. The greater the shift received by the unit, the greater the speed. Counting units convert the frequency shift into a speed reading displayed by the radar unit in miles per hour. Aiming the radar in the general direction of the target vehicle allows the operator to get a nearly instantaneous reading. The radio waves shoot out in a cone-shaped pattern that covers roughly two-thirds of a football field at a range of 1,000 feet. The radar unit will display the strongest return signal it receives, and a Doppler tone helps the officer confirm the reading is coming from the intended target.
Lidar (light detection and ranging), on the other hand, sends out a laser beam. The lidar unit determines the distance to the target vehicle, calculating the time it takes the beam to reflect off of the vehicle and return to the unit. Lidar units use change in distance and time as key components to determine the target vehicle’s speed.
Though they are essentially the same, used to estimate speed, they are completely different
If you have received a citation for speeding in Santa Barbara or in neighboring Santa Maria and Lompoc the likeliness of lidar and/or radar being used is highly probable. Lidar and radar are quite different, as are the defenses. Contact Santa Barbara Traffic Ticket Attorney Kenneth M Hallum. Consultations are free, you have options, and defenses.