Abstract: A terrain reference navigation system for an aircraft, surface vessel or subsurface vessel utilizing three sets of geo-physical correlation data. A kalman filter is used to correlate terrain data, electromagnetic data and gravimetric data with the output of a digital map of terrain, electromagnetic field and gravity. An optical disk stores the digitized data for sections of the globe. A Best of 3 selection process decides based on the errors in the kalman filter whether to accept the prediction of the terrain system, electromagnetic system or gravity system. An inertial navigation system uses the results of the Best of 3 selection to update aircraft, surface vessel or sub-surface vessel position and velocity and provide a more accurate positional estimate.

Abstract: A data compression/decompression method incorporating aliasing error reduction. An array of terrain data is first scanned for a set of modes and indexes are assigned to those modes. These modes are used as precision points for compression and decompression. A compressed index database is created using the associated modes for the original terrain data. If the number of modes exceed a predetermined number the number of modes is collapsed using an aliasing technique. The alias error is tracked during the compression cycle. Total aliasing error is kept to a local minimum. The compressed data is decompressed by decoding and accessing the index database for the elevation alias. Further compression is accomplished using a lossless coding technique.

Abstract: A dither stripper for laser gyro dither including a digital microcomputer which controls the stripping of the dither signal from the inertial navigation signal of the laser gyro. The dither stripper schedules internal A/D conversions using an A/D conversion arbitration scheme as well as calculates the expected system sample clock. Accurate dither stripping is achieved using a phase locked loop feedback system which compensates for real time changes in dither pickoff components while incorporating an accurate gain control mechanism.

Abstract: A delta-sigma modulator is provided with a multi-stage shift register coupled to receive as its input the output from a quantizer including an analog integrator. The serial digital output signal train from the shift register is fed back to the input of the integrator and because of the frequency division which takes place, for a given high clock rate, an operational amplifier with a lower gain/bandwidth product may be employed. The invention also includes a signal processor coupled to the output of the delta sigma modulator and which is arranged to provide an adaptive window based, decimation cycle whose exact timing is data dependent. The adaptive windowing process implemented in a microprocessor-based signal processor allows the first occurrence of a proper polarity state transition occurring during a window period to become the termination point of the computation cycle rather than providing a fixed time interval.

Abstract: The present invention discloses an apparatus to deposit thin films on a substrate. An ion beam produced by an ion gun, which is radio-frequency excited, impinges upon a target. The target is translatable laterally by a target holder to bring different target materials into contact with the ion beam. The targets are held at an angle to the ion beam. The target material sputtered off the target by collision with the ions is deposited on substrates held above the targets. The substrates are moved into and out of the path of the sputtered material by an unique rotating device for uniform deposition of the sputtered material.

Abstract: A device for measuring the position of an element utilizing a linear variable differential transducer. The primary of the transducer is excited by using a single pulse, causing an induced pulse to be created at the secondary coil. The induced pulse is compensated for the effects of distortion. The induced pulse is sampled and compared with the input pulse to determine the amount of attenuation caused by the transducer, from which the position of an element attached to the transducer can be calculated.

Abstract: A digital rebalance system for an inertial reference sensor. The rebalance system associates the error signal output with a sample value of a stored error signal and generates a rebalancing torquing pattern waveform in response to the error signal. The system includes waveform generation and error signal processing devices, precision timing devices, passive compensation circuitry and a precision switching circuit.

Abstract: A method for attaching dither motors to a ring laser gyro block such that the dither motors do not induce a large amount of stress into the laser gyro block. Attachment is achieved by the use of a center post having a diameter substantially smaller than the size of the laser gyro block.

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: Transcendental function approximation using a regional approximation look-up table, offset lookup table, scaling shifter and interpolation adder/subtractor. Rapid fixed-point arithmetic calculations can be accomplished which approximate values of transcendental functions to a predetermined accuracy. An N bit argument is used to produce an N bit result allowing the placement of the radix point in the two numbers to be different. Different parts of the input argument are fed in parallel to the regional approximation look-up table and the offset lookup table. A scaling shifter converts the output of the offset lookup table and regional lookup table to a result usable by the interpolation adder/subtractor processor. The regional approximation lookup table also provides information to the interpolation processor which provides the N bit approximation.

Abstract: The present invention discloses an ion beam gun wherein the ions are produced by radio-frequency excitation. A plasma is created in a vessel, or chamber, by ionizing gas molecules by means of a coil about the outside of the vessel. The coil receives radio-frequency energy which ionizes the gas molecules. The inside of the vessel contains an anode and resonator to assist in shaping and containing the plasma. The resonator acts as an internal electrode to produce eddy currents generated by the radio-frequency energy to enhance the plasma. A multi-apertured screen grid also helps contain and shape the plasma within the chamber while a multi-apertured accelerator grid is used to extract the ions from the ion beam gun.

Abstract: A cathode for use in a gas discharge device that is resistant to sputtering and therefore extends the life of the gas discharge device. The configuration of the cathode effectively uses the hollow cathode effect allowing the laser to operate with a lower excitation voltage. That configuration involves a body having a cavity therein and an entrance port to the cavity. Within the cavity there exists a protrusion extending from an interior surface toward the entrance port.

Abstract: A full field memory based stroke written vector occluder consisting of a first full field memory as the primary occlusion mechanism, and a second full field memory as a quantized error correction occlusion function. The apparatus includes a mechanism for generating the address of the second full field memory from the address of the first full field memory added to the least significant bit of the address plus or minus 1. The apparatus also includes an OR gate to provide the real occlusion function which is the result of accessing either or both of the full field memories.

Abstract: Apparatus and an associated method are described for testing liquid crystal matrix displays that can be performed prior to the assembly of the display. This display procedure involves applying of square wave signal to the control elements and a sine wave signal to the input terminal of an active element associated with the pixel under test. By selection of the sine wave signal frequency, the modulation products resulting from the combination of the square wave signals and the sine wave signal fall between the components resulting from the application of the square wave signal alone. As a result of the symmetry of the modulation components, a comb filter can be used to select the modulation components. The power of the transmitted modulation products provides a figure of merit for the active element associated with the pixel.

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 radar altimeter incorporates circuitry for automatically adjusting altitude readings for variations caused by altitude and temperature changes. Normal target tracking of the radar is intermittently interrupted and a calibration sequence is interjected. The current altitude and receiver AGC information at the time of each interruption is temporarily stored and a test is initiated in which a pseudo radar return at that altitude is introduced to the receiver. The receiver operates on the pseudo return as it would on an actual return. The transmit power is adjusted automatically for the correct signal level at the tracker. The resultant altitude measured for the pseudo return is compared to a known test altitude and any difference is stored away as a correction factor to be applied to the altitude reading which had been stored at the time that its operation had been interrupted to perform the calibration test.

Abstract: A pulse Doppler radar altimeter designed to resolve the ambiguous range problem associated with the use of a pulse repetition interval, which is less than the aircraft altitude, includes a radar transmitter configured to transmit first and second series of pulses where the first series has a pulse repetition interval slightly different from the pulse repetition interval of the second series. At a time when the first series is being transmitted, the receiver electronics including a range gate and a tracker searches for ground returns and positions the range gate in time coincidence with the detected ground return. Control then shifts so that the second series of pulses is transmitted and a determination is made whether overlap of the range gate with the ground return from the second series corresponds to the same altitude as when the first series was involved.

Abstract: A millimeter wave microstrip shunt-mounted PIN diode switch having its DC ground separate from RF ground is created by utilizing a fan structure (radial stub) having a radius of approximately one-quarter wavelength to provide an RF ground at that location and then coupling the DC bias supplies to that RF ground location. By doing so and by proper attention to known design practices for laying out microstrip circuitry, the need for blocking capacitors required by prior art arrangements is eliminated.

Abstract: A remote registration and calibration system for a hybrid video display. The registration and calibration functions are performed by a computer. Display mounted switches are advantageously employed. The computer system samples the state of an array of switches and then performs calibration functions based on the state of the switches.

Abstract: Apparatus and method for providing x, y an z values so as to construct figures from unit vectors rotated in three space wherein the x, y and z values result from processing construction and rotation parameters according to the following relationships:.DELTA.X'=.DELTA.X COS(G.sub.z)+.DELTA.Y SIN(G.sub.z).DELTA.Y'=-.DELTA.X SIN(G.sub.z)+.DELTA.Y COS (G.sub.z).DELTA.Z'=.DELTA.Zwhere,.DELTA.X=COS(R.sub.z) COS(R.sub.y +G.sub.y).DELTA.Y=COS(R.sub.z) SIN(R.sub.y +G.sub.y) SIN(G.sub.x)-SIN(R.sub.z) COS(G.sub.x).DELTA.Z=COS(R.sub.z) SIN(R.sub.y +G.sub.y) COS(G.sub.x)+SIN(R.sub.z) SIN(G.sub.x)X=X+.DELTA.X', Y=Y+.DELTA.Y', Z=Z+.DELTA.Z'and, R.sub.z and R.sub.y are construction rotation parameters for the Z and Y axes, respectively, and G.sub.y, G.sub.x and G.sub.z are global rotation parameters for the Y, X and Z axes, respectively. As used in a graphics display system, the invention provides offset values to an apparatus for summing offset values from a specified point.