The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 08, 1979
Filed:
Jun. 21, 1977
Glenn Mamon, Chestnut Hill, MA (US);
Douglas G Youmans, Watertown, MA (US);
Jeffrey A Volp, Billerica, MA (US);
The Charles Stark Draper Laboratory, Inc., Cambridge, MA (US);
Abstract
A system for determining the range between a reference point and a target by transmitting a pulse toward the target and measuring the time until receipt of a pulse reflected by the target. In an airborne laser altimeter configuration, the reference point may be located on an aircraft and a pulsed laser is directed along a vertical path to the ground. The system measures the duration of a pulse sequence including a first (or start) pulse, representing a pulse transmitted from the reference point, and the last of one or more associated subsequent return pulses, where the return pulses represent reflections of the transmitted pulse from both the ground and interfering objects located between the reference point and the ground. The system generates a replica of the start pulse and subsequent pulses, with the replica being delayed by a predetermined period from the start pulse and associated subsequent return pulses. The undelayed pulse sequence is processed to determine the number of return pulses in that sequence, and this detected number of pulses is utilized to enable a gate which passes only the last return pulse in the delayed pulse sequence. A time interval measurement is performed by a single precision time interval counter which is initiated by the start pulse of the delayed pulse sequence and is disabled by the gated last, or stop, pulse of the delayed pulse sequence.