Abstract: A system primarily for industrial security; to detect intruder movement in interior areas. A Doppler detecting, bi-static system utilizing range (time-delay) areas of varying shapes. The detection containment obtained is orders of magnitude more absolute than conventional systems which depend on antenna beam shaping to obtain varying detection coverage. Range discrimination is effected by bi-phase modulating the transmitted CW radio frequency waves according to a maximal length pseudo-random code. The autocorrelation function provides the ideal range discrimination response for the application. Omni antenna coverages are provided and a lower rf band is used than in conventional systems for this use, affording lower moving clutter susceptibility and better coverage. The general pseudo-random coding techniques are available within the state of the Radar Arts.