Abstract: An air-to-ground tracking guidance system wherein a tracker/illuminator and a terminally guided seeker are utilized. Target track is initially established by the tracker/illuminator which also provides a target illuminating signal. Semi-active tracking utilizing the reflected target illuminating signal is employed by the seeker after launch. During this period of operation, the seeker is prevented from tracking the tracker/illuminator by means of a unique guard radiation system. The semi-active mode is supplemented by an active mode in which the seeker tracks reflections of a target illumination signal emitted therefrom and a passive mode during which the seeker tracks the radiometric thermal emission from the target. While in the semi-active mode, the seeker establishes a range track that is independent of the semi-active mode of operation. This permits the seeker to automatically convert the mode of operation to active and passive at the desired positions along the seeker's track.

Abstract: The invention is a novel noise reference generator for use in amplitude comparison radiometric systems for the purpose of rapid precision control of the over-all gain of the radiometer receiver. The reference generator operates by cyclic modulation of the temperature of a unique planar thin film microresistor which may be disposed in a constant temperature environment. A strip transmission circuit provides a common path for the microresistor heater currrent and for the generated noise signals, along with means for separating these currents.