Video correlation tracker

Abstract

A correlation tracker for generating correlation error tracking signals over an entire video frame. Video information from a scanning receiver is inputted into the correlation tracker in serial form. The correlation tracker first incorporates apparatus to generate a reference map in pixel format. Reference map pixel information for one video frame plus one video line is stored in a memory to allow the calculation of azimuth and elevation optimal weighting values for each pixel in the field of view. Each video pixel of data being received during the current frame is then summed with the corresponding reference map pixel from the prior frame and the result multiplied by the appropriate weighting function. Each resultant product is then combined in an accumulator to form azimuth and elevation correlation error signals which are composite indications of the frame-to-frame correlation over the entire field of view. The weighting factors for each pixel are also combined and accumulatively added over the entire image plane to form three adaptive scale factors at the end of each frame which are combined with the azimuth and elevation correlation error signals to eliminate cross-coupling and generate cross-coupling-free correlation error signals. Drift compensation may also be provided by combining the adaptive scale factors and several predetermined constants to recursively calculate a drift correction which when combined with the cross-coupling-free correlation error signals generates drift-free correlation error signals.