Calibration Cycle
Definition
The periodic re-certification of a speed-measurement device against a traceable reference, usually annually for radar guns and every six months for LIDAR. The certificate is the document the prosecution produces in court.
- Radar guns
- Typically annual re-certification
- LIDAR devices
- Typically every six months
- Reference
- Traceable calibration standard
- Court role
- Certificate produced as evidence of accuracy
Common questions
Why does a defence challenge to a speeding case often focus on the calibration certificate?+
If the device's calibration certificate is missing, expired, or shows the device was outside its certified re-certification window at the time of the reading, the reliability of the speed measurement itself becomes open to challenge, independent of how the device was operated on the day.
Does calibration alone guarantee an accurate speed reading in a specific case?+
No. Calibration establishes the device met accuracy standards as of the calibration date, but individual readings can still be affected by operator error, angle of measurement, or environmental interference, so operational procedure is checked separately from the calibration record.
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...
- 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...
- Doppler Effect
- The change in observed frequency when the source and the observer move relative to each other. A radar gun emits a known...
- 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...