Importance

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Abstract

A method and an apparatus for measuring the distance to a target according to the time-of-flight of laser pulses. The apparatus includes a transmitter of laser impulses toward the target and a receiver of laser impulses reflected from the target. A driver of the transmitter generates a first time signal corresponding to the transmission. The receiver generates a second time signal corresponding to the reception. A delay generator delays at least one of the first and second signals to compensate for time errors, and provides a third signal corresponding to the first signal and a fourth signal corresponding to the second signal, such that a time difference between the third and fourth signals is exactly equal to the time-of-flight of the transmitted pulses. Additional circuitry delays the earlier of the third and fourth signals so as to provide signals that are delayed by incrementally increasing amounts of time relative to the earlier signal, and matches a time the later signal of the third and fourth signals to one of the incrementally delayed signals, thereby to obtain a time delay value approximating the time-of-flight. In a preferred embodiment, the delay generators are digitally programmable and are controlled by a microprocessor to find the match to the later of the third and fourth signals by using a binary search procedure.

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First Claim