Abstract: A vehicle obstruction avoidance system particularly for reversing a vehicle towards obstructions not visible in the wing mirrors. A radar head is mounted on the rear bumper, the head including a scanner and sensor. The total range of interest is only a few meters and provides very little time for processing echoes from all range cells in the range. The invention provides a system in which only one range cell is processed with each pulse transmission and the range cell is stepped on for the next pulse.