Tektronix, Inc.

Kevin B McDonald

Florian Gene Bell

William A Trent

Michael S Overton

Glenn Bateman

Richard I Lane

An input signal is sampled by alternately coupling the input signal and a reference level to a sample storage element, whereby the magnitude of the signal stored by the storage element immediately following application of the input signal to the storage element is a function of the input signal magnitude and the magnitude of the signal stored by the storage element immediately preceding coupling of the input signal to the storage element is a function of the reference level.

Method of calibrating and controlling the optical power output of an OTDR

Sample and hold with intermediate reset voltage outside of the magnitude

An avalanche photodiode non-linearity correction circuit cancels a portion of a non-linear recovery error response by the APD to an input signal by using the fact that the non-linear recovery error is only mildly dependent upon the APD gain. The gain of the APD is varied from data acquisition cycle to data acquisition cycle, with the acquired data being stored. The stored data from consecutive data acquisition cycles are combined in a summation circuit to effectively cancel a significant portion of the non-linear recovery error response.

Avalanche photodiode non-linearity cancellation

An automatic trigger mask for an optical time domain reflectometer inhibits high optical level pulses in a received optical signal from saturating an optical detector in a receiver. A portion of the received optical signal is compared with a threshold signal derived from the output of the receiver. If the portion of the received optical signal exceeds the threshold signal, then a control signal is generated to open an optical switch in the optical path to the receiver so that the high optical level pulses are inhibited from reaching the optical detector.

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Bend, OR, United States of America

Kevin B McDonald