Abstract: A line monitoring arrangement of an optical fibre communications system carrying system data signals includes a test sequence generator, an optical transmitter and a correlator. The generator generates a sequence of test pulses, and the optical transmitter repeatedly launches the sequence of test pulses into a first end of a transmission line forming part of the communications system. The correlator correlates signals received at the first end of the transmission line with the sequence of test pulses to identify returned test pulse sequences. The test pulse sequences and system data signals are superimposed onto the transmission line.

Abstract: An apparatus for generating three dimensional graphic symbols. Each symbol includes a plurality of polygons referenced to a datum point in a cartesian coordinate system, for example, having X, Y and Z axes. Apparatus for storing a vertex list is included. The vertex list characterizes each symbol and includes a starting address and a plurality of vertices, wherein each vertex is comprised of X, Y, and Z offsets from the datum point. In one embodiment, each vertex has a surface normal assigned to it. Connected to the vertex storing apparatus is an apparatus for registering an icon ID reference numeral to each symbol. An apparatus for mapping to the starting address is further connected to an output of the registering apparatus. The mapping apparatus uses the icon ID reference numeral to point to each symbol's starting address. Apparatus for transforming the vertex list into a different coordinate system is arranged to receive the vertex list from the vertex storing apparatus.

Abstract: A method and apparatus for providing a texture mapped perspective view for digital map systems. The system includes apparatus for storing elevation data, apparatus for storing texture data, apparatus for scanning a projected view volume from the elevation data storing apparatus, apparatus for processing, apparatus for generating a plurality of planar polygons and apparatus for rendering images. The processing apparatus further includes apparatus for receiving the scanned projected view volume from the scanning apparatus, transforming the scanned projected view volume from object space to screen space, and computing surface normals at each vertex of each polygon so as to modulate texture space pixel intensity. The generating apparatus generates the plurality of planar polygons from the transformed vertices and supplies them to the rendering apparatus which then shades each of the planar polygons.

Abstract: A bus interface controller for use in a digital information system. The bus interface comprises more than four bi-directional data channels which are multiplexed so as to accomplish switching of data from any channel to any or all of the remaining channels. The device is preferably embedded in a substate comprising gallium arsenide material and operates at a frequency of at least 25 MHz.

Abstract: A method for storage and retrieval of digital map data representative of a tessellated sphere including five zones. Firstly, the number of tessellations for each zone is defined. Secondly, the range of each zone is defined. Next, the radius of the sphere is defined. A sphereical data base is then created by warping the digital map data into the spherical data base by latitude and longitude. Finally, data from the spherical data base is retrieved and the data may be displayed on a cathode ray tube (CRT) display or a flat panel liquid crystal display.

Abstract: An apparatus for reading a first addressable memory and writing into a second addressable memory wherein the first addressable memory is logically arranged in a rectangular matrix and is scanned at an arbitrary angle with respect to the matrix for producing a plurality of scan patterns whose parameters can be altered and controlled by an external source, while the second addressable memory, also arranged in a rectangular matrix, is written into along parallel rows and columns. The apparatus is particularly adapted for use with a digital map display system having an airborne computer for generation the scan parameters.

Abstract: A digital mapping display system for an aircraft wherein map data from a mass memory unit is periodically loaded into RAM in the form of a cache memory in accordance with the aircraft trajectory. The cache memory is randomly addressable within the physical address space of a control processor, individual segments of the cache memory being loaded with map data and updated while other segments are being displayed, thereby avoiding the inherent delay of accessing the mass memory unit and addressing the entire RAM array. Parallel processing of map data and symbology facilitate a real-time display.