Abstract: An attitude reference system which uses microwave radiometry to sense the orientation of a vehicle. A fundamental fact of microwave radiometry is that more natural energy emanates from the earth than from the sky. The difference in energy, which is directly proportional to temperature, can be used to estimate attitudinal position. Microwave antennas mounted on an escape vehicle, such as an aircraft ejection seat, receive energy from different directions in a base plane and from a direction perpendicular to the base plane. Vehicle orientation relative to the earth is discerned by comparing the sensed radiometric temperature received from each antenna direction, and seat guidance equipment is programmed to steer the seat in a predefined direction based upon the radiometrically sensed orientation.

Abstract: A horizon reference system has a plurality of microwave radiation sensors which are selectively connected by a controller to a superheterodyne receiver. The output signals of the receiver are processed in conjunction with antenna selection data to provide roll angle with reference to the horizon and roll angle rate data about any particular axis of the platform on which the sensors are mounted.