Abstract: An improved method for finding the mask threshold for a maskable bilevel correlator operates on a series of frames of information. Beginning with an initial threshold, two rates are computed. The rate of change of the correlation peak magnitude P.sub.(T), a function of threshold T, with respect to the change in the value of the mask threshold T, or (dP.sub.(T) /dT), and the corresponding rate of change of correlation reference pixels with magnitude exceeding the mask threshold, U.sub.(T), a function of threshold T, with respect to the change in the value of the mask threshold T, or (dU.sub.(T) /dT), are measured. The correct, or best, value of the threshold occurs when .vertline.dP.sub.(T) /dT.vertline..gtoreq.0.5*.vertline.dU.sub.(T) /dT.vertline..
Type:
Grant
Filed:
September 27, 1991
Date of Patent:
November 9, 1993
Assignee:
Hughes Aircraft Comany
Inventors:
Thomas K. Lo, Teresa A. Hinkle, Lop G. Ng, deceased Sacks