COMPUTER

Digital signals relating to the north reference and variable phase components of the output of the VOR receiver are used along with slant range corrected output of distance measuring equipment to generate a synthetic, stepped sinewave representing the phasor from the VOR ground station to the aircraft. Stored digital waypoint distance (Rho) and bearing are combined with north reference signals to generate a synthetic, stepped sinewave representing the phasor of the VOR to a selected waypoint. The aircraft phasor is subtracted from the waypoint phasor and the resultant passed through a low pass filter, thereby providing a sinewave, the amplitude of which represents the distance from the aircraft to the waypoint and the phase of which represents the bearing of the aircraft track to the waypoint with respect to north, which comprises the phasor, or vector, to the waypoint. This phasor is resolved into X and Y components (arbitrarily with respect to north) each component then being constant slew rate filtered, and, with north reference signals, synthetic phasors are recreated, summed and filtered so as to provide a slew rate filtered phasor representing the vector from the aircraft to the waypoint, the magnitude of which is used to drive a distance to waypoint indicator, the phasor being combined with OBS track angle information to provide cross track error and to/from indications.