Abstract: The field observed by a video camera includes a desired target which is to be encompassed by an electronic window. The acquisition of the target is controlled initially by a light pen to position the electronic window on the target displayed on the screen of a receiver. Automatic video tracking proceeds then by measuring the mean video level in the vicinity of the target, adjusting the signal to this level and rectifying it, and then periodically measuring the difference in energy in the two successive halves of the window along the axis in question, this measurement giving the positional divergence between the center of the window and the energy center of the target. Corresponding error signals are used to move the window to keep the target centered therein.