Doppler Effect
Definition
The change in observed frequency when the source and the observer move relative to each other. A radar gun emits a known microwave frequency and measures the frequency of the reflected wave; the shift converts directly to vehicle speed.
Related terms
- ANPR
- Automatic Number Plate Recognition. A camera plus OCR pipeline that reads vehicle number plates at speed and logs the plate, timestamp, and...
- Calibration Cycle
- The periodic re-certification of a speed-measurement device against a traceable reference, usually annually for radar guns and every six months for LIDAR....
- Cosine Error
- The under-reading of true speed that occurs when the radar or LIDAR beam is not perfectly aligned with the vehicle's direction of...
- FASTag-ANPR Fusion
- Indian highway tolling pairs RFID FASTag reads with ANPR cameras at every electronic toll gantry, creating a national vehicle-position log that investigators...
- Time-of-Flight (LIDAR)
- A measurement principle where the device emits short laser pulses and times how long each pulse takes to return. Multiple pulses over...
Explained in
- Speed Detection Devices: Radar, LIDAR and ANPRThe change in observed frequency when the source and the observer move relative to each other. A radar gun emits a known microwave frequency and measures the f...