Abstract: When a lightwave passes through a transmission grating, diffracted beams appear at the output or opposite side of the grating that are effectively Doppler shifted in frequency (phase) whereby a detector system can compare the phase of the zero order and higher order beams to obtain an indication of position. Multiple passes through the grating increase resolution for a given wavelength of a laser signal. The resolution can be improved further by using a smaller wavelength laser to generate the grating itself. Since the grating must only have a pitch sufficient to produce diffracted orders, inexpensive, ultraviolet wavelength lasers can be utilized and still obtain high resolution detection.

Abstract: A pulse-width modulated DC-DC power supply is illustrated with overvoltage protection which upon initial detection momentarily shuts down the pulse-width modulating portion of the control loop for a given cycle. If the overvoltage condition persists for more than a prescribed number of cycles or amount of time, the power supply is shut down permanently. The delay between momentary and permanent shut down being used to allow system operation to be maintained with minimal damage (voltage induced load stress) where large voltage transients may be temporarily introduced into the system.

Abstract: Many prior control circuits inject a small amplitude control tone into the prime signal path where the distortion added to the prime or main signal by the control tone does not present a significant corruption of the prime signal. This control tone is detected and, based on the detected parameters, the prime signal is adjusted as to one of its parameters such as amplitude. If there are variable frequency spurious signals that may produce products within the bandwidth of the control system, the operation of the control circuit can be completely disrupted. The present invention overcomes the prior art problem by continuously sweeping the frequency of the control tone whereby the detection of the spurious signals in the operation of the control circuit occurs such a small percentage of the time that the control circuit can maintain reliable control operation.

Abstract: A combination latch and handle which comprises an L-shaped piece of deformable plastic material having a pocket intermediate two locking protrutions. The pocket, which holds a spring metal clip, fits into a slot on the edge of a piece of sheet metal. The locking protrusions pass through openings on either side of the slot to lock the latch and handle into place securely as the forces to install same are at right angles to the forces to engage or disengage the latching mechanism. The spring metal clip is designed to co-act with a pin on a mating piece of sheet metal.

Abstract: When synchronous communication systems such as SONET (synchronous optical network) need to change data formats, the resulting periodically discontinuous clock signal associated with the data after overhead has been removed, has to be smoothed to a periodically continuous clock signal associated with resynchronized output data. The SONET format employs pointers which may be described as large phase hit error signals relative the clock signal. The present invention illustrates a technique for slowly integrating the large phase hit error signals into the clock smoothing process so that jitter in the smoothed clock output is held below previously obtainable limits. This is accomplished by high-pass filtering the large phase hit signal and summing it with the periodically discontinuous clock before applying it to a second order type 2 low-pass filter system which filter system employs phase locked loop synchronizing techniques.

Abstract: It has been determined that etchants which are used in forming the topography of a semiconductor device act to etch very quickly semiconductor oxides as compared to the action on the semiconductor material itself. If the oxides are immediately below the surface of the etchant mask, undercutting of the mask will occur and etched grooves will vary in width and shape. Thus, it is imperative in order to obtain consistent and repeatable etching action, that all native oxides be removed from the surface of the semiconductor to be etched, and that they be prevented from forming between the semiconductor material and the mask. This is accomplished by making sure that after removing the native oxide material from the surface to be masked and etched, the body is placed in an oxygen free environment before its temperature is raised to a temperature at which further native oxides may form. Thus, undercutting or underetching of the mask is prevented.

Abstract: Holographic techniques are utilized to create a lens or magnifying effect in a surface film. This surface film deflects the light rays so that they leave the film at a much different angle then they arrive at the film. Since holographically produced lenses are more efficient in the transmission mode at angles deviating substantially from near normal angles of incidence, the images to be displayed for the left eye of a viewer are substantially displaced from those images for the right eye of the viewer as opposed to the prior art presentation of holographic stereoscopic displays which positioned all of the left eye images immediately adjacent all of the right eye images for a given segment of the total picture.

Abstract: Precisely controlled grooves are formed in a semiconductor wafer as part of a total photolithographic process of producing the circuitry and the V-grooves for precise registration of the circuitry relative the edges of the individual chips of the wafer. The same registration facilitates automated electrical testing of each of the chip circuits on the wafer prior to the controlled disassembly of the array of chips into individual die. The design of the electrical connections on the array before disassociation into individual die also facilitates a mass burn-in of the circuits which burn-in tends to identify and eliminate parts subject to early failure.

Abstract: A high-pass filter which provides a digital word output indicative of a high-pass filter function of the quantity of logic "1" inputs to the counter. The output of a counter is low-pass filtered and applied in conjunction with a bias signal to a second counter which counts clock inputs from a value determined by the count input from the low-pass filter to a predetermined limit and outputs a feedback pulse to be used by the first counter in opposition to a second bias string of pulses where the second bias string of pulses and the feedback signal have substantially the same frequency of pulse rate under steady state conditions of the filter.

Abstract: An adaptive TDMA (time division multiple access) communication system is illustrated which dynamically maintains potentially different frequencies between nodes of the communication system using a process of communicating the quality of received signals between the nodes and storing this information so that an optimum frequency band can be selected whereby whenever signal quality deteriorates, an alternate frequency can be selected to provide continued communications. An embodiment of the system spans both high frequency (HF) and very high frequency (VHF) to establish the communications through atmospheric induced refractions (reflections) beyond line of sight between directly communicating nodes of the system. Further, the system uses frequency hopping both for signal transmission security and for node identification. When a node is traffic idle and also on a periodic maintenance basis, frequency bands other than the traffic frequency are analyzed for potential future use.

Abstract: Typically time multiplexed switches use an indirect addressing scheme where a set of data bits in a first addressable memory define addresses in a second addressable memory as part of a read function to time switch an output data stream previously stored in the second memory. In a situtation where there are less channels of traffic than there are potential addresses as defined by the number of bits stored in the first memory, the most significant bits can be used to define first and second ranges where the first range defines a set of data bits used for indirect addressing of traffic information and the second range can be used in a direct addressing mode to substitute the lesser significant bits of those stored in the first memory in place of traffic memory data bits when the stored most significant bits are detected to define the second range of data bits.

Abstract: A deformable or flexible diplexer element provides a common input to two separate bandpass filter arrays. The construction of the element and the associated diplexer filter containers are designed such that the average distance between each end of the element and its associated resonator can be easily adjusted to optimize coupling therebetween. With the individual adjustment and associated variable coupling, the filter responses are individually optimized to the appropriate frequencies.

Abstract: An electro-optical module for facilitating connection between a fiber optic cable connector and an electrical circuit includes an interlocking tongue-and-groove design between the skirts of the module and an electro-optical active device. Within the electro-optical active device, a lens provides hermetic sealing to the case so as to eliminate the requirement for an additional window. A barrel providing partial enclosure for the lens is used to facilitate alignment with the fiber optic cable. Finally, the total module includes mechanisms so that exact spacing is obtained between the light source and the end of the fiber optic cable whereby the beam waist of the light when the device is used in the transmission mode occurs interior to the cable rather than at the surface to accommodate manufacturing tolerances, bending forces and to reduce noise generated by reflections, etc.

Abstract: A process is illustrated to provide plated through holes for connecting between opposite sides of a circuit board such as an insulating ceramic substrate while maintaining a smooth surface on the circuit side to facilitate the process of defining the circuit pattern. The plated-through hole process is designed to uniformly cap or plug all of the plated-through holes to prevent solder from the backside from flowing through the holes to the circuit side and damaging (short-circuitry adjacent paths) the finished product.

Abstract: A variable frequency oscillator which is completely digital and does not use high frequency parts higher than 50 megahertz and yet operates at 50 MHz. Variable frequency is obtained by increment and decrement inputs supplied to a control block which selects between selected phase holding signal inputs obtained from an external source. The output pulse is returned to the control mechanism to start the cycle over. Internal to the control is an algorithm or control sequence which uses a make-before-break approach to prevent glitches which tend to occur during change of phase.

Abstract: In some applications of power amplifiers, a prescribed or given amount of distortion is permissible under many operational conditions, as long as lesser amounts of distortion are available upon command. It has been ascertained as a part of the present invention that, by reducing the bias current in one or more of the output stages of a power amplifier, acceptable distortion specifications can be maintained under conditions of low power consumption and low output power requirements while retaining the ability to have more demanding linearity requirement specifications by increasing the bias current to a more linear portion of the I-V (current-voltage) curve and optionally providing increased output signal power. The bias condition of reduced power results in a conservation of electrical power requirements, a reduction of heat and temperature problems within the amplifier enclosure and accordingly an increase in component life and circuit reliability.

Abstract: A digital implementation of an analog phase detector is illustrated, wherein the novel aspect is the use of a low speed clock, which is passed through a delay line to provide ten different phases of clock signal. The circuitry is used to generate digital numbers on a basis similar to the pulses in an analog equivalent, which numbers are summed to provide a phase detected output.

Abstract: A conductive and mechanical energy absorbing gasket is used between an electronics package and a cover of an enclosure to provide microphonics isolation. The electronics package is secured to the cover via a gasket using isolation damping grommets and screws, so that the only substantial transmission of mechanical energy from the case to the electronic package is through the screws themselves. The conductivity of the gasket places the entire enclosure at the same potential as the metal in the electronic package and as the mounting screws, and thus helps prevent the screws from acting as RF antennas.

Abstract: The present invention accomplishes the desirable end result of capacitively coupling the outer shield portion of a coaxial jack connector to an outer panel or chassis while having the jack connector physically and directly electrically connected to a back plane or motherboard within the chassis. The connection to the outside environment is via an opening in the outer or shielding chassis through which the mating portion of the jack connector is passed. A prior art approach used a capacitively connected coaxial jack connector at the panel and a cable connected internal to the chassis from this panel connector to a normal coaxial connector on the back plane. The present invention eliminates two of the three components of the prior art approach.

Abstract: A digital clock recovery circuit is presented which uses a delay line to produce a plurality of delayed sample signals. The sample signals are used to sample incoming data in a phase detector and the resultant sampled data is then resampled by the tentatively correct apparatus clock output signal. The resampled data provides a direct indication of the phase difference beween the data and the clock and the value can be obtained using a summing circuit. If the summed amount is outside an allowable range of values, a phase altering signal is supplied to an oscillator to change the phase of the apparatus clock output signal.