Abstract: A first variable tracking gate is generated which activates a sample and hold circuit connected to receive incoming signals from a doppler radar receiver and apply output signals therefrom to a threshold circuit which in turn supplies a signal to a range counter each time the signal from the sample and hold circuit exceeds a predetermined threshold, whereupon an output from the range counter decreases the range at which the tracking gate is generated. A second tracking gate, generated a short time after the beginning of the first tracking gate, activates a second sample and hold circuit connected to receive signals from the radar receiver and supplies signals through a second threshold circuit to the range counter to increase the range of the first gate when the signal from the second sample and hold exceeds a predetermined threshold and signals from the first sample and hold circuit are below the predetermined threshold.