Radar Guns Blog: Radar Gun News, Radar Gun Forum, Radar Gun Products, Radar Gun Reviews, Radar Gun Information, Radar Gun Advises

Recently a number of publications have reported a laser radar (lidar) measuring a vehicle speed at a range of 9,204 feet (1.7 miles). An operator would have difficulty seeing a vehicle at that range.

For a police lidar to measure a vehicle at that range the target would have to be a very large vehicle (a tractor-trailer), and the weather would have to be completely clear, cool, very dry (little or no humidity), and measured just before or after sunrise (least amount of background heat).

A well designed police lidar should ignore echoes greater than specified maximum operating range (typically about 2000 feet). A lidar that can measure a vehicle at 9000 has the receiver wide open to unwanted signals and interference sources and errors.

CopRadar

In the Hyde area of Manchester England a motorist was caught by a Speed Camera (Photo Radar) system, but not just for speeding. The motorist realized a radar system got him when the camera flash alerted him to the yellow speed camera (all UK speed cameras are painted yellow). The motorist was so enraged he reportedly back tracked and blew up the speed camera. The camera was damaged and rendered useless, however images of him speeding and returning to the scene were preserved (in the base located below the camera). The motorist got 4 months jail time (and probably a speeding ticket -- the least of his current problems).

Many UK speed cameras are fixed mounted, usually to a utility pole. Typically in the UK when a motorist goes after a speed camera they usually use an ax or paint. In 1983 the state of Texas (USA) tried a portable French-manufactured Ka band radar for a time but discontinued it's use because the units were being stolen. Photo speed cameras (photo radars) are extremely unpopular with the public worldwide.

CopRadar

Montreal (Canada) police are investigating a sergeant's (an 11 year veteran) role in a company that helps drivers contest speeding citations resulting from radar. Some question whether it is a conflict of interest for any police officer to have anything to do with any company that contest any traffic tickets.

The police sergeant claims he has followed all rules and regulations. The officer also states "Mistakes can be made every time a radar gun or a laser is used. There are grounds for a challenge in 10 per cent of cases."

I seriously question the 10 percent error rate. In general the error rates, based on my experiences, are either much higher or much lower depending on police department (or even officer). The way it really works is a properly maintained radar that is setup and operated by a highly trained officer almost always gets an accurate measurement. A radar improperly setup (all too common) will seldom (or more often never) get an accurate measurement.

CopRadar

Several cities in Oregon (including Portland) and Colorado state police have been reported to use laser radar to catch tailgaters (and speeders). Laser radars can display target speed and range from radar. The police aim the laser radar first at the lead vehicle front bumper, and then at the suspect tailgater front bumper. The officer gets both a range and speed reading on both targets (if targets are close enough to radar to be singled out).

Measuring distance between a moving vehicle and suspected tailgater with a laser radar using radar range information is difficult if not impossible. Laser radar typically takes at least 1/3 second or more to get a speed reading. The radar also displays the last (latest) range measurement (more useful data would be LAST range on lead vehicle and FIRST range on tailgater). Too many parameters are changing too fast to get accurate information about vehicles separation. The lead vehicle length is also a factor (range between rear of lead vehicle and front of tailgater).

To determine vehicle separation accurately the time difference between vehicles crossing a fixed point or landmark should be used (rear of lead vehicle and front of tailgater). If both vehicles are traveling at the same speed (this is usually the case) and a radar can measure the speed -- a timer could be used to calculate vehicle separation. However the timer accuracy required will be on the order of fractions of a second to measure vehicle separation with any accuracy (most difficult).

CopRadar

Across the United States a number of police departments have purchased Daimler-Chrysler Dodge Chargers equipped with microwave radar (a popular option). The corporation is actively pursuing the police car market estimated at about 70,000 vehicles. The Chargers are in direct competition with Ford's Crown Victorias.

The Charger's cost varies with options and are estimated to be between about $25,000 and $32,000. Estimated top speed is 130 - 150 mph (210 - 240 km/hr) using a Hemi engine rated between 340 and 395 horsepower. Acceleration is 0 to 60 mph (97 km/hr) in 6 seconds flat (0.45 G's). Options include (but not limited to) a microwave radar, various voice/data radios, computer, video system, GPS, and breathalyzer.

The new muscle cars are physically smaller and have more equipment (radar, video, GPS, keyboard, etc.) compared to the 1960's and 1970's muscle cars. Smaller size and more equipment leaves little room for the driver (officer). More equipment generally means more data and the potential for user (driver) overload (too much data/information to perceive/manage effectively).

CopRadar