License Plate Recognition Camera Specs — What Matters on a Jobsite LPR
LPR camera performance on a jobsite ingress depends on lens focal length, IR illumination, shutter speed, and processor speed — not just megapixel count. Guardtress deploys purpose-built LPR cameras that read plates at 90–98% capture rate day or night, at vehicle speeds up to 40 mph, at distances up to 60 feet.
What actually matters in an LPR camera
Lens focal length: 5–50mm varifocal is standard for jobsite ingress at 20–60ft. Wrong focal length = plates too small or too warped.
Shutter speed: 1/1000 sec minimum to freeze a plate on a moving vehicle. Slower shutters blur.
IR illumination: 850nm IR at 100+ feet — LPR works in total darkness because it uses IR-reflective plate coating.
Processor: on-camera OCR is faster than cloud OCR by a factor of 3–5x.
- Lens: 5–50mm varifocal
- Shutter: 1/1000 sec minimum
- IR: 850nm at 100+ ft
- OCR: on-camera, not cloud
Capture rate benchmarks
90–98% capture on plates from vehicles within 60 feet of the camera at speeds up to 40 mph — day or night — is the modern benchmark. Older systems drop to 50–70% at night or above 20 mph.
Guardtress LPR is spec'd to the modern benchmark and independently validated on a monthly test protocol.
Common jobsite deployment mistakes
Wrong angle: LPR camera aimed too high or too shallow catches plates at an angle that OCR can't read. Optimal aim: 15–25 degrees off horizontal.
Wrong distance: cameras too far from the ingress lane can't resolve plate detail. Wrong height: too high and the plate is warped; too low and headlight glare washes it out.
Optimal mount: 12–16 feet high, 30–50 feet from ingress lane.
- Angle: 15–25° off horizontal
- Mount height: 12–16 ft
- Distance from ingress lane: 30–50 ft
- Aim: directly at plate line, not vehicle body
Storage and search
LPR reads are stored with timestamp, geo, and confidence score. Guardtress retains 90 days of reads per site by default; longer retention is available for enterprise deployments.
Client portal search allows plate lookup, wildcard match, and time-window filter. HPD coordination on active investigations uses the same search interface.
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