Traffic Speed Camera Product

Overview

A traffic speed camera is a measurement instrument first and a camera second. Its output is not a photograph but a piece of legal evidence: a speed figure traceable to a type-approved measurement, bound to images that identify a specific vehicle at a specific place and time, signed so that none of it can be altered between the roadside and a courtroom. The engineering follows from that chain of custody.

A fixed installation combines a speed sensor — the Radar Unit, the Lidar Unit, or both — with the Enforcement Camera and Flash Unit aimed at the capture zone, all run by the Processing Unit inside the Cabinet and Pole Mount on a pole or gantry beside the carriageway.

Measuring speed

Doppler radar transmits a continuous or frequency-modulated signal at 24 or 34 GHz from the Planar Radar Antenna and measures the frequency shift of the reflection: a vehicle approaching at 100 km/h shifts a 24 GHz signal by about 4.4 kHz. Modern tracking radars go further than a single Doppler tone — the Radar Signal Processor runs FFT processing that resolves range, angle, and speed for dozens of targets at once, following each vehicle across up to six lanes and assigning every speed reading to a lane and position. That tracking is what lets one camera prosecute the correct vehicle out of a cluster, the failure case that retired older single-beam radars.

Lidar takes the opposite approach: an extremely narrow 905 nm beam from the Pulsed Laser Diode, with speed computed from successive time-of-flight ranges — the Time-to-Digital Converter resolves each pulse's round trip to centimetres, and a few hundred pulses over a third of a second yield speed to ±1 km/h. The narrow beam makes target attribution unambiguous, which is why lidar dominates where vehicle-specific evidence is contested. Enforcement devices are type-approved against standards such as OIML R 91, with tolerances of ±1 km/h up to 100 km/h and ±1% above; enforcement thresholds add margin on top.

Capturing the evidence

When the tracked speed exceeds the limit at the enforcement line, the Camera Interface Board triggers an exposure timed so the vehicle sits in the calibrated capture zone. The camera is a 9–12 MP global-shutter unit behind a 50–100 mm Lens Assembly; at highway closing speeds, exposures run around 1/1000 s to keep the plate sharp, which is why flash is needed even in daylight shadow.

The Flash Unit either dumps a xenon capacitor bank — the visible flash drivers know — or fires an 850 nm infrared LED bank invisible to traffic. IR systems pair the IR Bandpass Filter filter with the flash wavelength, so the camera sees its own illumination and little else; retroreflective number plates return the IR strongly, making plates bright and legible at night at the cost of monochrome images. Jurisdictions requiring driver identification use visible flash and colour capture; rear-photographing installations avoid dazzling drivers.

Each violation package — typically two images proving motion across a known baseline, the speed record, lane, direction, and a GNSS Receiver time fix — is assembled by the Compute SoC Module, which also runs automatic number plate recognition locally in under 200 ms. The Cryptographic Module signs the record; the signature, encrypted Evidence SSD storage, Security Door Lock, and Tamper Switch together form the integrity argument the evidence relies on. Records upload over the LTE/5G Modem through a VPN to the back office, where human review precedes any notice being issued.

Living outdoors

The cabinet is a harsher environment than most electronics ever see: −30 °C winters, +60 °C solar-loaded summers, salt spray, vibration from passing trucks, lightning transients on the mains, and deliberate vandalism. The Heated Camera Window and heated Optical Window Assembly keep optics clear of frost and rain film; the Heating Element and Ventilation Fan hold internal temperature; the Surge Protection Device clamps induced transients; and the Li-ion Cell, 18650 backup pack rides through grid dips so no violation in progress is lost. Average-speed (point-to-point) enforcement uses the same hardware at two or more sites, matching plates by ANPR and computing speed from transit time over a known distance — no radar needed, and compliance extends over kilometres rather than metres around a single pole. Empirically, fixed cameras cut fatal and serious crashes at treated sites by roughly 20–40%, which is the case made for the whole apparatus.