Abstract: A Passive Navigation System (PNS) provides continuous updating of position, velocity, and attitude information of a vehicle without recourse to radiating or external navigation aids. The system accurately computes navigation information with the utilization of gravity sensors, gravimetric maps, vertical position, and velocity measurements. Sensor and map data are optimally processed by real time filtering to compute the best position, velocity, and attitude of the vehicle. The products of measured gravity gradients and the velocity of the vehicle are integrated over time to obtain a north, east, down gravity vector components which are combined with corresponding components obtained from a vertical deflection map in a complementary filter. North and east components of the combination are compared with the corresponding components from the vertical deflection map, while the down component of the gravity is compared to the down value obtained from a gravimeter.

Abstract: A laser comprises a cell containing xenon at high pressure and has its walls previous to high-velocity electrons. The cell is of cylindrical shape and constitutes the anode of a field-emission diode with the cathode of the diode surrounding the anode. Electrons emitted from the cathode thus travel radially inwardly and penetrate the anode walls to excite lasing action.