Abstract: A communication system and a method for using an approximating frequency synthesizer with frequency correction by digital signal processing (DSP) means to provide a radio transmitter or receiver with rapid high resolution tuning capabilities. A user selects a frequency upon which he wishes to transmit or receive information. An approximating synthesizer is used to provide an RF injection frequency. A radio controller interprets the user selected frequency and determines the closet available approximating synthesizer frequency. The controller commands the approximating synthesizer to the determined available frequency and calculates the difference in the determined available frequency and the user selected frequency. The calculated difference or error is passed on to the DSP for correction during frequency mixing in a single or multiple step process.

Abstract: A bidirectional amplifier apparatus comprising a plurality of diodes located in a ring structure around an amplifier device to be switched. Each pair of diodes are spaced approximately one quarter wavelength, at the frequency to be passed, in order to maximize isolation across the "off" diode pairs. Use of transmission line devices of approximately one quarter wavelength, at a desired frequency, provide a high impedance at the desired frequency while attenuating higher frequencies where the transmission line devices length approach one half wavelength. The use of the transmission line devices also provide a ground bias for the paired diodes.

Abstract: A tri-phase combiner/splitter system that has similar advantages to presently available binary combiner/splitter systems which uses quadrature couplers. Notably, the combiner input Voltage Standing Wave Ratio ("VSWR") remains at 1:1 for identical mismatch impedance at the output ports. There is also a complete cancellation of back-door intermodulation components for identical output device nonlinearities. An innovative wideband, 0.degree. three way combiner/splitter is the basic building block of the present invention. To achieve equal port impedances, a new wideband transmission line transformer is used. By using 60.degree. or 120.degree. phase equalization networks at the three, 0.degree. output ports, this device is converted to a wideband tri-phase combiner.For moderate bandwidths, a coupled transmission line version is possible using meandering strip lines in the same fashion used in quadrature coupler design.

Abstract: An apparatus for providing illumination to flat panel displays having a multi-walled encasement device, lighting means and a flat panel display. The multi-walled encasement device may be of a variety of shapes and serves to support the lighting means within the cavity formed by its walls. The fluorescent bulb is fabricated into a circular design and placed within the multi-walled encasement device thereby providing uniform light intensity across the flat panel display attached to the encasement device. The encasement device may contain convex or concave contouring to better direct or concentrate light wave intensity to the flat panel display.

Abstract: A control knob assembly primarily for use with devices utilizing flat panel display technology, each assembly having means for manipulating the electronic apparatus by using remote sensing capability to transfer control knob input into a control signal. The assembly is mounted on a bezel, affixed to the front side of the flat panel display and cooperates in conjunction with a plurality of photodiode devices located near the back side of the flat panel display. Photodiodes are located with respect to knob location so as to be able to detect knob adjustment by monitoring a reflected signal that is alternatively disrupted by knob adjustment. The photodiode devices may be infra-red light emitting diode as are well known in the prior art. Circuitry to the photodiode device is used to transmit detected knob adjustment to the appropriate device control circuitry.

Abstract: An apparatus and method of calibrating a digital to analog converter including means for establishing and storing a minimum and maximum analog endpoint value slightly in excess of the desired operating range of the DAC and then scaling each respective raw data point of the DAC within the established endpoint values.

Abstract: A digital amplitude modulator receives a plurality of phase coherent input signals from a plurality of amplifiers (A1-An) respectively representing the bits of a plural bit digital word and converts them to a single output signal on an output with a first plurality of transformers having transformer ratios which vary substantially in accordance with a power of two corresponding to the significance of the bit represented by the input signal being converted thereby and a second plurality of transformers having primaries connected to the first plurality of transformers, respectively, and secondaries all connected in series together to an output terminal and transformer ratios which vary in substantial accordance with the same powers of two that the transformer ratio of the first plurality of transformers to which they are connected vary.

Abstract: A system for controlling for gain and phase errors due to mismatches between signal channels in direct conversion receiver having a pair of signal channels carrying I and Q baseband component signals which are in quadrature. In accordance with the system new I' and Q' signals are generated which may be viewed as analogs of the I and Q baseband components but which are related to twice the phase angle defined by the original I and Q baseboard components signal components. Phase angles are determined based on the original I and Q baseband components signals and the new I' and Q' signals. An error signal is then formed from these signals which can be analyzed to determine the gain and phase errors affecting the I and Q baseband components. These components can then be adjusted to correct for gain and phase errors in order to compensate for hardware mismatches between the signal channels in the receiver.

Abstract: An integrated attitude director indicator and horizontal situation indicator is disclosed that utilizes stereopsis to combine information that normally requires two display surfaces onto a single electronic display. One embodiment of the display comprises left and right eye versions alternately presented on the display in synchronism with alternate eye shuttered lenses worn by the viewer. The viewer has an instantaneous sense of the real world direction from his aircraft as apparently suspended within a spherical grid. The integrated display provides a presentation somewhat similar to existing flat screen separate instruments with an aircraft symbol lying at the center of the sphere with roll, pitch and heading scales displayed on this sphere. The sphere itself has one color such as blue above the horizon line and a different color such as brown below the horizon line.