Choosing The Right Radar Detector
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Page 4 - Police Mistakes25% of All Radar Tickets are in Error Although all radar detectors are tested for accuracy by police agencies, radar and laser guns and their operators still make many mistakes. It is estimated that over 25% of all radar tickets are in error. The most noticeable and common mistakes include shadowing, RFI interference, cosine error and mechanical interference. Shadow Error Shadow Error occurs when the moving radar's "Low Doppler" incorrectly locks onto a large metal object like an 18 wheeler in front of the patrol car and adds the speed differential to the opposite lane target vehicles speed. VSS Low doppler is used to determine the patrol vehicles speed. Shadowing has and is being eliminated by interfacing the police radar gun into the vehicles speed sensor. This is known as VSS or Vehicle Speed Sensor interface. Now that the patrol car's speed is obtained by the vehicles own speed sensor, the low doppler signal from the police radar gun can be compared and accuracy is increased. RFI RFI stands for Radio Frequency Interference. Many poorly shielded radar guns speed readings will go blank when a commercial radio or police radar is keyed up. Cosine Errors Cosine error is standard with both radar and laser guns. The greater the transmission angles of the gun to the target vehicle, the greater the error. However, the angle is always to the advantage of the driver. It always shows a speed less than the actual speed. An example would be a speed radar gun transmitting at a 10' degree angle from the approaching target vehicle. The target vehicles actual speed is 60 mph but the radar gun shows 59 mph. The Most Troubling Error
This is an example of mechanical interference as the police car's heater/air conditioner fan was producing the erroneous speed reading. The fact remains, radar and laser guns still make mistakes. Landmark Ruling
The ruling states that laser guns may not target vehicles past 1,000 feet due to the gun's one millididadian beam divergence of 36" at that distance. Anything further than 1,000 the radar gun might incorrectly target an adjacent vehicle. >> New A user on our RadarDetector forum that goes by the nickname of Da Mail Man recently found himself falsely accused of speeding because of the "shadowing" effect. Because of the information provided here and on other forums he fought back and submitted his trial by decoration and won! I wish to thank Da Mail Man for allowing you to download the legal documents he used to beat his unjust citation so you can build your own defense if the need ever arises.
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The third error is the most troubling. In 2004, the Pennsylvania State Police purchased hundreds of new radar guns. They were clocking rocks at 70 mph. 
New Jersey Superior Court Judge Reginald Stanton issued a landmark ruling in 1996. 
