Abstract: A test detect and shut off circuit for a BiCMOS integrated circuit is presented. The test detector/shutoff detects the presence of a predetermined test condition in the BiCMOS integrated circuit (IC), and upon detection of the predetermined condition isolates (i.e., switches off) the bipolar circuit portion from the CMOS logic portion of the BiCMOS IC. In this way, bias current in the bipolar transistor circuit is eliminated, thereby facilitating IDD testing of the BiCMOS logic. The detector/shutoff is particularly designed for BiCMOS implementations wherein a single voltage rail supplies voltage V.sub.DD to the logic and bipolar circuit portions of the IC. Corresponding test detect and circuit isolation methods are also presented.

Abstract: This is a one of the many differential multiplier circuits providing a fast selection of a one set of differential input signals from a multiplexity of differential input signals in which a plurality of differential input circuits coupled to differential outputs can be selectively prevented from being propagated to the differential outputs by activating one or more switching circuits coupled to the differential output circuits.

Abstract: Pixels within a satellite camera (1, 2) image are precisely located in terms of latitude and longitude on a celestial body, such as the earth, being imaged. A computer (60) on the earth generates models (40, 50) of the satellite's orbit and attitude, respectively. The orbit model (40) is generated from measurements of stars and landmarks taken by the camera (1, 2), and by range data. The orbit model (40) is an expression of the satellite's latitude and longitude at the subsatellite point, and of the altitude of the satellite, as a function of time, using as coefficients (K) the six Keplerian elements at epoch. The attitude model (50) is based upon star measurements taken by each camera (1, 2). The attitude model (50) is a set of expressions for the deviations in a set of mutually orthogonal reference optical axes (x, y, z) as a function of time, for each camera (1, 2). Measured data is fit into the models (40, 50) using a walking least squares fit algorithm.