Three miles-long straightaways are linked by sharp, plunging S-curves where the two-lane county highway drops down through low-water crossings quaintly termed dry washes in the desert southwest. The three are not in alignment and at the 28,000-foot mark, the road not only plunges sharply downhill but also switches directions, angling some 40 degrees away from the radar.

The police radar vehicle is parked on the shoulder in the middle of a blind, downhill curve, facing traffic. At almost the instant the radar vehicle can first been seen, the radar operator begins targeting cars as they hove into view at a point-blank 650 feet of range.

20-foot-long test fixture is positioned across the target vehicle cowl area, extending 10 feet laterally to each side of vehicle. Police laser is tripod-mounted on opposite side of road, on the shoulder exactly 1,000 feet distant from target, aimed at the front license plate and transmitting continuously.

Detector is powered-up and, beginning fromn 15 feet away, moved laterally along fixture toward car centerline. When detector alerts to laser distance to centerline is noted. Process is repeated on opposite side and both Right and Left fields of view are averaged.