Abstract: The REAL TIME KEYBOARD SCANNER shown herein provides scanning and debouncing, but not multiple key resolution or buffering. At the end of each keyboard scan, the scanner produces a code indicating which key was depressed, or that no key was depressed, or that multiple keys were depressed. If this code is the same as the code in a valid-key register, then no change is made to the valid-key register and no debouncing is performed. If the codes differ, then debouncing is performed. The CPU served by the scanner can examine the code in the valid-key register whenever it finds such examination to be convenient, and need not tie up valuable processing time in continuously monitoring the valid-key register. If desired, an interrupt may be sent to the CPU when the code in the valid-key register is changed.

Abstract: An oscillator circuit provides a symmetrical signal without halving the frequency of a crystal oscillator 12. The input 14 of the crystal oscillator 12 is low pass filtered, and the output 18 of the filter 16 is differential voltage compared with the input 14 of the crystal oscillator 12. The output 22 of the differential voltage comparator 20 is symmetrical and of the same frequency as the crystal oscillator 12. The crystal oscillator 12 is preferably a Pierce oscillator.

Abstract: The ACCELERATION DISTORTION RESISTANT RING LASER GYRO (RLG) (10) shown here includes a control mirror (12) subject to distortion beyond the path length control capabilities of the RLG (10) when subjected to intense translational acceleration in the direction (20) perpendicular to the face of the control mirror (12). An anti-parallel compensating mirror (14) is provided to offset the path length change. Additional design flexibility may be obtained by replacing the compensating mirror (14) with a compensating group of mirrors.

Abstract: For use with a quartz angular rate sensor, a frequency and phase-locked synthesizer recovers a reference signal virtually free of phase noise, and generates a quadrature-phase reference signal for complex demodulation of the angular rate signal. The synthesizer also ensures a precisely adjusted phase shift of approximately zero across the drive tines of the sensor. Moreover, the digital synthesizer provides a precise numerical indication of the drive frequency, which can be used for compensation and automatic tuning of filters, such as a tracking filter, a filter in an automatic gain control, and notch filters in the phase and/or frequency detectors in the digital synthesizer. The tracking filter is used as a pre-filter for the synthesizer, and is responsive to a passband-width control signal generated from the magnitude of the frequency and phase error signal controlling the frequency generated by the synthesizer.

Abstract: Equivalent circuit parameters of a piezoelectric resonator are measured in order to precisely control the amplitude and/or frequency of oscillation of an oscillator including the resonator, or to compensate for variations in the amplitude and/or frequency of oscillation. Significant variations are caused by shunt capacitance, and to a lesser degree, series resistance. The equivalent circuit parameters are measured by exciting the resonator at a plurality of frequencies, measuring responses of the resonator at the frequencies, including a complex response at one of the frequencies, and determining a value of the shunt capacitance from the responses. Preferably, the resonator is simultaneously and continuously excited at three different frequencies, one of which is approximately the resonant frequency of the resonator.

Abstract: The invention uses transferable solder bump connection techniques in combination with a disposable test board to test and burn-in "as received" (i.e., untested) dies. Using transferable solder bumps, a die is first attached to the top of a disposable test board. The test board can be designed to allow 100% functional testing of the die as well as burn-in. Dies that successfully complete the test and burn-in process are considered to be "known good dies." Next, heat is applied to remove the known good die from the test board. A property of the invention is that solder bumps transfer with the die such that it can be used immediately in a flip-chip configuration and affixed to a MCM or other circuit board.

Abstract: A method to fabricate a tuning fork resonator gyro which uses non-piezoelectric substrate structure is proposed. The tuning fork structure can be effectively rendered piezoelectric for activation and sensing by thin film deposition of a piezoelectric material. Electrical excitation of the piezo film excites vibrations in the structure of the drive tuning fork, and the gyro signal generated due to rotation can be picked up from the piezo film on the signal tuning fork. Most piezoelectric films have a much higher piezoelectric coupling than crystalline quartz, the material used in the prior art. The piezoelectric films on mechanically hard non-piezoelectric substrates are simpler for fabrication, electroding, and have a number of other advantages over the prior art. Fabrication of the tuning fork structures can be done more simply than the prior art, and deposition of the piezo films can be accomplished by sol-gel, or other thin film techniques.

Abstract: A ring laser gyroscope detector lens system for mounting on a ring laser gyroscope body having a resonant cavity. The ring laser gyroscope body has CW and CCW counterpropagating light beams propagating in a plane normal to the rate input axis of the ring laser gyroscope. The ring laser gyroscope detector lens system comprises a means for extracting a component of each of the CW and a CCW light beams from the cavity and for providing extracted CW and CCW beams. A means for combining the extracted CW and CCW beams to form an interference light source receives the extracted light. A planar array of detector element receives light from an objective lens means responsive to the interference light source. The objective lens means is typically a cylindrical lens that forms an interference light source pattern on the planar array of detector elements. A bias and amplification means is provided for conditioning each of the detectors in the array to be independently responsive to incident light intensity.

Abstract: A sensor such as a quartz angular rate sensor is operated in a closed-loop mode including feedback of a control signal. The sensor produces a modulated carrier frequency signal. For stable operation of the feedback loop, the control signal is obtained from the modulated carrier frequency signal by complex demodulation of the modulated signal to produce an in-phase demodulated signal and a quadrature-phase demodulated signal, and the in-phase demodulated signal and the quadrature-phase demodulated signal are filtered by a complex equalizing filter to produce an equalized in-phase signal and an equalized quadrature-phase signal. The equalized in-phase signal represents information sensed by the sensor, and phase of a demodulation reference signal is adjusted to minimize appearance of the information in the equalized quadrature-phase signal. The equalized in-phase and quadrature-phase signals are complex modulated at the carrier frequency to produce the control signal.

Abstract: The SELF FILLING AND EMPTYING DATA PIPE LINE disclosed herein fills a pipeline register automatically when it is empty, without requiring a double request from the receiver. When the pipeline register is full, it is maintained in a full condition for as long as the sender has valid data. When the sender no longer has valid data, the pipeline empties itself of all remaining valid data to the receiver.

Abstract: A ring laser gyro scale factor enhancement circuit connected between at least one power supply voltage level and a reference potential for conditioning at least a first and second input signal from a ring laser gyro assembly, the first and second input signals being essentially sinusoidal and having a common first input signal frequency, the second input signal having a predetermined first phase relationship with the first input signal for a first ring laser gyro rotational sense and a second predetermined phase relationship with the first input signal for a second ring laser gyro rotational sense.

Abstract: The FAULT TOLERANT GATE ARRAY USING DUPLICATION ONLY shown here renders AND-drives-OR, and OR-drives-AND, gate arrays as fault tolerant as when triplicated, but does so by only duplicating the array. A test input is added to each of gates of the bottom tier of the two arrays. When a test signal is applied, the same output should be produced by both arrays. This output should be the same as an expected test output, which is known in advance. When the test signal is withdrawn, the two arrays should continue to produce the same output as each other, although it may or may not be the same as the output under test. If any of these three conditions is not met, the failure may be used to determine the correct output, the failed array, and the nature of the failure.

Abstract: The MODEM WITH DIGITAL ISOLATION removes the relatively large heavy isolation transformer from the Data Access Arrangement and substitutes two tiny pulse transformers between the Integrated Analog and Digital Signal Processor with multiplexers and demultiplexers to eliminate analog distortion and multiple leads, and to accommodate Lap Top/Palm Top computers, while enhancing data speeds. The combination with surge protection enables both uncommon and common mode protection.

Abstract: A MOVING VEHICLE CLASSIFIER WITH ITERATIVE DECONVOLVER ESTIMATOR deconvolves a signal in which a plurality of sensed signals, which originate from a common signal source (namely, a moving vehicle) and traverse differing signal paths, are used to formulate an initial unconstrained estimation of the signal source as a reference signal. Preselected constraints are placed on the reference signal to generate an estimate of the source signal, and of a source signal matrix, for the plurality of input sensors. A pseudoinverse of the source matrix is then used to form an estimate of the impulse response of the propagation paths for the signals. The estimates of signal path impulse response are used in combination with the input signals to again estimate the unconstrained reference signal. This is in turn used to estimate a new source signal matrix and path responses. These estimation steps are repeated in a series of iterative steps until a point of minimum variance from the received signals is reached.

Abstract: A purely chemical method for forming a layer of insoluble sulfides on semiconductor surfaces in order to passivate their surfaces and more particularly to a method of forming a layer of insoluble sulfides on a HgCdTe device surface.

Abstract: To demonstrate a signal, the signal is sampled and each sample of the signal is multiplied by the sine and the cosine of a phase angle indicating when the sample was taken from the signal. The sinusoidal signal for producing an in-phase demodulated signal is Chebychev-approximation derived and computed as a selected even or odd polynomial, depending on whether the phase angle falls within one of a plurality of angular ranges. So that the error in the synthetic sinusoid is minimax and so that the even and odd polynomials have similar computational complexity, the angular ranges for the even polynomial exceed the angular ranges for the odd polynomial. Preferably, the sinusoid for producing a quadrature-phase demodulated signal is computed as a differential of the sinusoid spliced from the odd and even polynomials. Therefore the quadrature-phase demodulated signal can be provided with a minimal increase in computational complexity.

Abstract: An apparatus and method are disclosed for classifying a signal among a plurality of potential signal sources or events in which a signal embodying values for predefined source features is received and conditional likelihoods are determined for the correspondence of each feature value with each of the plurality of events. The individual conditional likelihood values for each feature which corresponds to a common event are multiplied together to form an overall conditional likelihood that any event in question is the source of the signal. The total likelihood products are then sorted into maximum and minimum values, with the maximum likelihood forming a tentative output designation. The ranked values are then examined by a decision logic element to determine if they satisfy certain minimum absolute and relative value threshold limits to verify if the maximum or next higher level likelihood values designate proper output choices.

Abstract: A ring laser gyroscope radiation-resistant detector lens system for mounting on a ring laser gyroscope body having a resonant cavity. The ring laser gyroscope body has CW and CCW counterpropagating light beams propagating in a plane normal to the rate input axis of the ring laser gyroscope. The ring laser gyroscope detector lens system comprises a means for extracting a component of each of the CW and a CCW light beams from the cavity and for combining the extracted CW and CCW beams to form a substantially circular interference light source. A planar array of detector element receives light from an objective lens means responsive to the interference light source. The objective lens means is a cylindrical lens that forms an elliptically-shaped interference light source pattern on a first and second adjacent pair of detectors in an array of four detector elements.

Abstract: A ring laser gyro, having: an envelope for an optically resonant cavity having a gain bore section, the envelope containing an active gas medium. The envelope contains electrically energizable electrode means having at least two electrodes at electrode locations within the envelope for establishing an electrical discharge in an active gas medium between the electrode locations. The electrical discharge excites a pair of light beams along a lasting path between the electrode locations. The light beams counterpropagate in the optically resonant cavity. The envelope is coupled to means for generating an output signal for the gyro by measuring a difference in the frequencies of the light beams. The active gas medium has an axial current driven gas flow and a return gas flow induced by the electrical discharge, the resultant gas flow contributing to bias errors in the output signal. The envelope also comprises a gas bypass cavity adapted to pneumatically couple the electrode locations along the gain bore.

Abstract: A COMBINED DECIMATION/INTERPOLATION FILTER FOR ADC AND DAC (analog-to-digital converter and digital-to-analog converter) provides a single filter which may be used both as a decimation filter and as an interpolation filter. It is simple and inexpensive. It gains simplicity and inexpensivenes by carefully selecting the tap weights of the filter, cascading multiple filters, time domain multiplexing the multiple filters into a single filter, and using adders instead of multipliers to provide the tap weights.