Speed-measuring device performance specifications : across-the-road radar module
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Summary
This document establishes minimum performance specifications and verification procedures for automated, across-the-road (ATR) radar speed-measuring devices used by law enforcement agencies. Developed by the National Highway Traffic Safety Administration (NHTSA) in cooperation with the International Association of Chiefs of Police (IACP) and the National Institute of Standards and Technology (NIST), the specifications aim to ensure the accuracy and reliability of radar systems that measure vehicle speeds and potentially record images of violators. The document serves as a technical baseline for procurement, encouraging manufacturers to meet or exceed these standards to maintain public and judicial confidence in speed enforcement evidence. The specifications apply to stationary radar devices that transmit continuous wave microwave beams across roadways and process Doppler shifts from reflected signals. The document defines strict requirements for manufacturer-provided equipment, labeling, and operational information, including installation instructions and power supply details. Technical requirements cover microwave transmission characteristics, such as frequency stability within assigned X, K, or Ka-bands, and antenna beamwidth limits (e.g., no more than 12° for X-band). Devices must also withstand environmental extremes, including temperatures from -30°C to 60°C and 90% humidity, while maintaining accuracy. Specific protocols mandate that tuning forks used for calibration remain within ±½% of their specified frequency, and that radar displays show speeds within ±2 km/h (±1 mph) of the tuning fork’s nominal speed. Performance testing includes rigorous evaluations of signal processing and electromagnetic interference. ATR devices must accurately measure speeds between 32 km/h (20 mph) and 160 km/h (100 mph), with field operation accuracy tolerances of +2 km/h to –(3 km/h + 0.01 times actual speed). The specifications require devices to reject erroneous readings caused by simulated interference from vehicle alternators, ignition systems, air conditioners, windshield wipers, and police or citizen band radio transceivers. Additionally, devices must include low-voltage indicators that activate before performance degrades and must not display erroneous speeds during power surges or when switching from off to on. The document outlines detailed test procedures using specialized equipment, such as target simulators, anechoic chambers, and multifunction synthesizers, to verify compliance with these standards. The significance of this document lies in its role as a standardized framework for evaluating the technical competence of ATR radar devices. By defining clear minimum performance thresholds and testing methodologies, NHTSA provides law enforcement administrators with a reliable tool for procurement decisions. The specifications are intended to reduce the likelihood of erroneous speed measurements, thereby enhancing the integrity of traffic enforcement data presented in courts. The document encourages ongoing review and revision, ensuring that radar technology standards evolve alongside advancements in device manufacturing and operational requirements.
Key finding
The document defines technical performance specifications and testing protocols for across-the-road radar speed-measuring devices to ensure accuracy and reliability for law enforcement use.
Methodology
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Provenance
The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).
| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | rosap | — | — | 2 | 2026-05-23 |
| archive | success | — | — | — | 1 | 2026-05-23 |
| extract | success | cached | — | — | 2 | 2026-06-10 |
| clean | success | — | — | — | 1 | 2026-06-01 |
| chunk | success | — | — | — | 1 | 2026-06-01 |
| embed | success | — | — | — | 1 | 2026-06-02 |
| enrich | success | — | — | — | 1 | 2026-05-23 |
| promote | success | — | — | — | 1 | 2026-05-23 |
| summarize | success | llm | qwen3.6-27b-prismaquant | summ-v5 | 3 | 2026-06-10 |
| tag | success | vector_similarity | — | — | 24 | 2026-06-11 |
| verify | success | — | — | — | 2 | 2026-06-10 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.
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