Abstract: A new and improved differential pulse code modulation (DPCM) encoding and decoding method and apparatus which is capable of transmission with minimum bandwidth, is not affected by data transition density, requires no direct current (DC) response of the transmission link, and suffers from minimal ambiguity in resolution of the digital data.

Abstract: A method of planar mapping defects in a window having an edge surface and a planar surface. The method comprises of steps of mounting the window on a support surface. Then a light sensitive paper is placed adjacent to window surface. A light source is positioned adjacent the window edge. The window is then illuminated with the source of light for a predetermined interval of time. Defects on the surface of the glass, as well as in the interior of the glass are detected by analyzing the developed light sensitive paper. The light source must be in the form of optical fibers or a light tube whose light transmitting ends are placed near the edge surface of the window.

Abstract: A method of producing single-class and multi-class composite classification maps from multispectral data is provided. The multispectral data is transformed into a binary matrix format which is then encoded on an optical medium such as photographic film. The encoded data is holographically correlated with coded patterns representing selected spectral signatures to produce signal-class classification maps. Several single-class maps are optically superimposed to produce multi-class composite classification maps.

Abstract: Disclosed is a circular computer and system for determining the sun angle relative to the horizon from any given place and at any time. The computer includes transparent, rotatably mounted discs on both sides of the circular disc member. Printed on one side of the circular disc member are outer and inner circular sets of indicia respectively representative of site longitude and Greenwich Mean Time. Printed on an associated one of the rotatable discs is a set of indicia representative of Solar Time. Printed on the other side of the circular disc member are parallel lines representative of latitude between diametral representations of North and South poles. Elliptical lines extending between the North and South poles are proportionally disposed on the surface to scale Solar Time in hours. Printed on the other associated one of the rotatable discs are parallel lines representative of sun angle and a perpendicularly arranged sun elevation line.

Abstract: A Self-Contained Breathing Apparatus with automatic redundant fluid pressure controls and a facemask mounted low pressure warning device. The apparatus utilizes two stages of pressure regulation wherein the final stage is the demand regulator that delivers the breathing gas to the wearer. The first state includes a pair of pressure regulators connected in parallel with different outlet pressures, both of which reduce the pressure of the stored supply gas to pressures compatible with the second stage breathing demand regulator. A primary regulator in the first stage delivers a low output pressure to the second stage demand regulator. In the event of a "failure closed" condition of the primary regulator an automatic transfer valve switches on the backup regulator and communicates its slightly higher outlet pressure to the demand regulator.