Abstract: A system for receiving electromagnetic energy with reduced signal aliasing in the cross-scan direction. The system is adapted to be mounted on a spacecraft or an aircraft for movement over a surface in the cross-scan direction and has a sensor for receiving electromagnetic energy. The invention (10) includes an arrangement for directing energy to the sensor which has an astigmatic blur in the cross-scan direction which is effective to reduce aliasing of a signal transmitted or received by the system in the cross-scan direction of movement. In the illustrative embodiment, the invention (10) includes an array (20) of radiometric detectors. A reflective optical arrangement directs energy from a surface to the detector array. The optical arrangement includes at least one mirror (16) which has a small controlled cylindrical surface perturbation which introduces an astigmatic blur into the received image which reduces aliasing of the signal in the cross-scan direction.

Abstract: A satellite orientation detection system disposed to detect the pointing orientation of a geosynchronous satellite (10) relative to a reference location on the earth. The present invention is also capable of ascertaining the angular orientation of a longitudinal axis of the satellite (10) relative to a defined axis on the surface of the earth. A ground station (20) is included for transmitting a first linearly polarized and a second circularly polarized electromagnetic reference beam. The present system also includes a receive antenna (28) coupled to the satellite (10) for receiving the first and second reference beams and for generating an antenna-beam pattern P1 and P2 disposed to rotate about a reference axis A. A rotating polarizer arrangement (44), aligned with the receive antenna (28), periodically varies the portion of the linearly polarized energy within the first reference beam transmitted thereby.

Abstract: A variable phase time delay and signal aggregation ssystem is disclosed. The invention is adapted for use in scanning detection system and serves to maintain spatial resolution on a target surface independent of scan angle. The invention includes means for detecting electromagnetic signals from the surface area. The detector means includes a plurality of detector elements. Each detector element generates a corresponding first plurality of output signals representative of the response of the detector to energy received from the surface area within the field of view of the detector as the detection system scans through a predetermined range. Control means are included for selectively clocking the output signals from the detector elements to phase the relative timing thereof as a function of the scan angle. Means are included to aggregate these signals to generate a combined output signal having the predetermined spatial resolution.

Abstract: Apparatus is disclosed for providing a predetermined surface scan velocity of the projected field of view of a scanning instrument. The invention is adapted for use in a scanning instrument having scan drive means including an inertial element and detector means coupled to the inertial element for detecting or projecting radiation during a scan. The invention includes cam means mechanically coupled to said inertial element and supported, by a frame, to pivot therewith. The cam means includes a cam having a contour which is varied to provide a specific surface scan velocity profile for the projected field of view. A spring is coupled to the cam via a bearing which translates in response to the contour of the cam as the cam and the inertial element pivot during scan. The spring is attached to the frame to maintain the bearing in contact with the cam. The spring effectively stores energy from and restores energy to the inertial element via the bearing and the cam.

Abstract: An angular scan drive system is disclosed which permits the range of motion of a scanning mechanism to be selectively extended. The invention includes a mass (typically the scanning assembly) which is pivotally attached to a frame to scan in an oscillatory motion during a normal course of operation. A spring is included for applying a restoring force between the frame and the mass and, in accordance with the teachings of the invention, a mechanism is included for selectively coupling and decoupling the mass and the frame through the spring. In a particular embodiment, for example, the mechanism decouples the spring from the frame and attaches the free (frame) end of the spring to the mass on command during a specified portion of the scan cycle. Thus, both ends of the spring are attached to the mass thereby removing the restoring force of the spring from the assembly.