GB1436740A - Semi-automated surveying apparatus - Google Patents

Abstract

1436740 Ground profile measurement apparatus DEFENCE SECRETARY OF STATE FOR 5 Sept 1974 [11 Sept 1973] 42655/73 Heading G1A Ground profile measuring apparatus comprises a light source producing a collimated, horizontal beam, a ground follower on which is mounted a target comprising a series of equally spaced, vertically disposed areas, photo-detectors, each receiving light from a separate target area and a recorder for indicating which detector is illuminated and the distance the ground follower has travelled from a datum. The source may be a laser with a mechanically oscillated mirror producing a horizontal scan and the ground follower may be a wheel, mounted for relative vertical movement to the back of a vehicle. The detectors may be connected to the target areas by light guides. The photo-detector outputs (1 when illuminated) are fed in parallel into shift register 21. Pulses from clock 22 are fed as shift pulses to register 21 and are counted by counter 23. Circuit 24 produces an output on a 0 to 1 transition and logic circuitry 25 then passes the contents of counter 23 to store 26 thence via D/A converter 27 to recorder 28 where it is recorded against ground follower displacement. If the count in 23 reaches the number of stages in the shift register 21, a failed signal is produced. The above circuit indicates the lowest illuminated photo-detector. When several detectors are illuminated, the mean can be determined by a circuitry modification which feeds half the clock pulses to counter 23 between the 0 to 1 and the 1 to 0 transitions in the shift register output.