LiDAR & Speed Cameras

LiDAR Speed Detection

LiDAR (Light Detection and Ranging) speed guns use infrared laser pulses to measure vehicle speed. Unlike radar, which uses radio waves, LiDAR emits tightly focused beams of near-infrared light (typically 904 nm wavelength) that can target individual vehicles in traffic.

How LiDAR Speed Guns Work

• Laser pulse: The gun emits thousands of infrared light pulses per second (typically 100-200 pulses)
• Time-of-flight: Each pulse travels to the target vehicle and reflects back to the gun
• Distance calculation: Speed is calculated by measuring the change in distance over time: Speed = (Distance₂ - Distance₁) / Time
• Pulse rate: Higher pulse rates give more accurate readings at longer distances
• Range: Typical effective range is 300-1,200 meters, depending on conditions

LiDAR vs Radar for Speed Detection

• Beam width: LiDAR has a very narrow beam (~3 milliradians), allowing targeting of specific vehicles. Radar beams are much wider (6-24 degrees), making it harder to identify which vehicle is being measured
• Instant reading: LiDAR provides a speed reading in under 1 second. Radar typically requires 2-3 seconds of tracking
• Accuracy: LiDAR is accurate to ±1 km/h. Radar is accurate to ±1-2 km/h
• Court admissibility: Both are accepted as evidence, but LiDAR readings are harder to challenge because they target a specific vehicle
• Cost: LiDAR guns cost $2,000-$5,000. Radar systems cost $1,000-$3,000

Common LiDAR/Radar Frequencies

• 904 nm (LiDAR): Near-infrared laser, the standard wavelength for police LiDAR
• X-band (10.525 GHz): Legacy radar, still used in some jurisdictions
• K-band (24.150 GHz): Most common radar band for traffic enforcement
• Ka-band (33.4-36.0 GHz): Used by Stalker Dual and newer radar systems
• 24.125 GHz (K-band): Also used in vehicle speedometers (Doppler radar)

Automated Speed Cameras

Automated speed enforcement systems combine radar or LiDAR with cameras and ANPR (Automatic Number Plate Recognition) to issue tickets without a police officer present. These systems are widely deployed in Europe, Australia, and parts of the United States.

Types of Photo Radar Systems

• Fixed cameras: Permanently mounted at known speed hotspots, often with warning signs
• Mobile cameras: Mounted on portable trailers or vehicles, moved between locations
• Average speed cameras: Measure time between two points to calculate average speed (e.g., SPECS in UK, Tolltickets in Germany)
• Red light cameras: Combined with speed detection to catch both red-light running and speeding

Detection and Countermeasures

• Radar detectors: Legal in most US states, illegal in most of Europe, Canada, and Australia
• LiDAR jammers: Illegal in most jurisdictions (federal law in US prohibits jamming any radar/laser)
• Laser shifters: Some devices can detect LiDAR and provide warning before the officer gets a reading
• License plate covers: Illegal in many jurisdictions, designed to defeat ANPR cameras

Legal Considerations

• Accuracy requirements: Most jurisdictions require radar/LiDAR to be calibrated before and after use
• Officer certification: Police must be trained and certified to operate speed detection equipment
• Moving vs stationary: Rules differ for moving radar (in patrol car) vs stationary enforcement
• Speed tolerances: Officers typically allow 3-5 mph tolerance before issuing citations