A method and apparatus for reducing a vibratory response in a structure using a tuning object. The technique minimizes the dwell time in searching for a satellite signal in cells of a search space by comparing the peak-power-to-average ratio to one or more thresholds at one or more intermediate points during the search in a code phaseDoppler frequency bin. The method then estimates the depth of each keypoint, where depth is the distance from the feature to the camera.