Abstract: Accurate vehicle pitch and roll can be computed from a corresponding signal loop which receives inertial data input contaminated by the effects of gravity on a vehicle. Data from Doppler radar is compared to the inertial data and an error signal dependent on pitch or roll angle is substracted from the input inertial data resulting in the generation of accurate navigational parameters.

Abstract: A doppler radar/inertial system is provided for producing navigational and fire control information for an aircraft, and which includes means for developing vertical reference signals accurately at one location and for then transferring the signals to a second location without incurring errors due to aircraft flexure. The system includes high quality accelerometers and gyroscopes mounted at one location in the aircraft for developing accurate vertical reference signals; and a high quality accelerometer and low cost gyroscope at a second location where accurate vertical reference information is required. The system includes circuitry for comparing the output of the high quality accelerometer at the second location with the accelerometer outputs at the first location, the difference of which is a function of the error in the vertical reference at the second location, as indicated by the low cost gyroscope.