Douglas A Hill

US Patent:

41719077, Oct 23, 1979

Filed:

May 25, 1978

Appl. No.:

5/909373

Inventors:

Douglas G. Hill - Solana Beach CA
Richard N. Jekel - La Mesa CA
William W. Busche - San Diego CA
James E. Stufflebeam - San Diego CA
Robert L. Bruce - San Diego CA

Assignee:

Cubic Western Data - San Diego CA

International Classification:

G01C 308
G01B 1126

US Classification:

356 5

Abstract:

A device for measuring distances to a target includes electronic circuits for generating a light which is amplitude modulated by three selectable frequencies. Also included are optics for focusing the amplitude modulated light onto the target, and for receiving reflection of the light therefrom. Additional circuits convert the received light to electrical signals representative thereof, and compute the phase angles between these signals and the amplitude modulating signals. The distance to the target is then calculated based on these phase angles and the wavelength of frequencies equal to the differences between the three selectable frequencies. Another circuit uses an accelerometer to measure vertical angle to the target, and further distance measurements are made based thereon. Still other circuits compensate for a variety of potential error causing conditions, such as signal waveform asymmetry and component tolerance. A subassembly of the device is mountable on a theodolite telescope and utilizes folded optics in order to be plungeable.