Abstract: Adaptive IIR digital notch filters useful with RF receivers for reducing interference. One or more notch filters automatically tune, to an interferer frequency, via adapting of coefficients in the z-transform. Each notch tunes independently of any other.

Abstract: A high performance global positioning system receiver including a first circuit section adapted for operative association with an antenna means and including components for receiving, amplifying, and converting transmitted signals from analog-to-digital signals; and a second circuit section including components for correcting Doppler frequency shifts in the transmitted signal, removing any codes from the digitized transmitted signal, and processing and preparing the digitized transmitted signals for operative utilization by a computer processor. A substantial part of the first circuit section is reducible to micronized format, whereas the entire second circuit section is reducible to micronized format.

Abstract: The switching frequency of switching power supplies using bipolar emitter-follower transistor amplifiers to drive field-effect output transistors is increased from a currently typical frequency of 100 KHz to at least 1.5 MHz. by reducing the heating in the bipolar transistors. The heating, which is caused by the inherent 0.7 volt drop in the base-emitter junction of the bipolar transistor, is eliminated by feeding back from a dual core output transformer, a compensating voltage equal to the junction drop, the feedback winding being wound over only one core, and the output signal windings being wound over both cores. The flux in the feedback winding core of the transformer is limited by means of a diode to keep the feedback voltage substantially the same as the forward voltage of the base-emitter junction of the bipolar transistor. The core of the transformer is temperature compensating to keep the feedback voltage correct over temperature extremes.

Abstract: Data from long range aids such as the global positioning system (GPS) and an inertial navigation system (INS) and short range aids such as a microwave landing system (MLS) are used to smoothly and automatically transition an aircraft from the long range aids to the short range aids. During cruise a Kalman filter combines data from the global positioning system and the inertial navigation system to provide accurate enroute information. When the aircraft arrives in the vicinity of the airport and begins to acquire valid data from the microwave landing system, the Kalman filter is calibrated with the MLS data to permit Precision landing with GPS/INS data alone in case the MLS system subsequently fails. In addition, navigation information begins to be derived from a weighted sum of the GPS/INS and MLS data, the weighting being determined by distance from the airport. In a first region farthest from the airport, the GPS/INS data is given a 1.

Abstract: In a skywave adaptable communication network, the time required to initiate communications between two transceivers can often be an important factor where the propagation characteristics of signals at various frequencies may bary drastically with time. The present invention not only improves upon known prior art by accepting the first frequency that it hears as a communication frequency when two nodes are attempting to communicate from a known list of probe frequencies to be transmitted at known times, it initially uses predictive frequencies in probe signal format during the time that would later be used for traffic information after link-up has occurred where the predictive frequencies may be based on algorithms, experience or whatever. Once link-up has occurred, the probe signals are used to allow the system to then adaptively change to better quality signals as these better quality signals are received, analyzed and compared with present working frequency signals.

Abstract: In a skywave adaptable communications network, the time required to initiate communications between two transceivers can often be an important factor where the propagation characteristics of signals at various frequencies vary drastically with time. The present invention improved upon the prior art by accepting the first frequency that it hears as a communication frequency when two nodes are attempting to communicate from a known list of frequencies to be transmitted at known times. The system then adaptively changes to better quality signals as these better quality signals are received, analyzed and compared with present working frequency signals.

Abstract: The average RF power output of an independent sideband diversity radio transmitter, modulated by a multiple tone data signal, is increased while the RF output peak envelope voltage is held constant. For diversity operation the same information, as a combination of the data tones, is applied to both the upper and lower sideband channels of the RF translator. Adding predetermined phase shifts between the upper and lower sideband audio tone pairs results in a reduced peak envelope voltage at the composite RF output. The final RF amplifier gain can then be increased resulting in a higher average RF power output.

Abstract: An electromagnetic shield for components mounted to a printed circuit board includes an electrically conductive wall for interconnection to the printed circuit board for generally surrounding the components. The wall includes a top edge. The wall is disposed generally perpendicular to the printed circuit board. An electrically conductive cover for covering the area surrounded by the wall includes a top portion disposed generally parallel to the printed circuit board and a flange disposed generally parallel to the wall. The top portion of the cover includes a plurality of spaced apart springs disposed along the periphery of the cover for selectively engaging the top edge of the wall when the cover is positioned to enclose the area surrounded by the wall.

Abstract: A circuit is illustrated for eliminating a repetitiously occurring or constant frequency pulse signal from a train of signal pulses. The design is such that a plurality of such circuits can be connected in series to eliminate several of various frequency repetitious pulse signals, leaving only asynchronous signals in the pulse stream presented to downstream circuitry. The concept used is to record the time between two pulses and delete the passage of any signal during a time subsequent to the second of the two pulses by an amount equal to the difference between the first two pulses. If a pulse is detected during that time window, the circuit continues to blank out the passage of pulses for as long as a pulse is detected during the time window.

Abstract: Aircraft rendezvous is facilitated by operating airborne remote aircraft TACAN stations in the inverse bearing mode and using low data rate range interrogation and range reply signals for determining bearing. An aircraft determines its bearing to another similarly equipped aircraft by switching its antenna to an omnidirectional pattern and transmitting range interrogation pulses and then switching its antenna to a rotating directional pattern and receiving range interrogation and range reply signals from the other aircraft. The TACAN station calculates the bearing to the other aircraft using the low data rate signals, thereby obviating the necessity of using a high power base TACAN station.

Abstract: A laser signal coupling device one embodiment of which comprises a transmitter where a laser diode is coupled to a single mode fiber optic cable through the use of a lens whose position relative the diode is kept constant but whose length is adjusted to obtain a beam waist for the focused beam at some predefined point such as inside the end of the fiber optic cable. Such a positioning of the beam waist can increase the yield by reducing the effect of alignment variations in axial, radial and angular directions as well as reduce noise from fiber end surface reflections. The same concept may be used to accurately focus signaling received from an optic cable, in a surface of a signal detector. Further, the concept may be used for focusing between optic cable of different types such as converting from multi-mode to single-mode fiber optic cable.

Abstract: A four directional self-aligning wedge clamp having a series of wedge elements is shown. A rod is centrally disposed through the series of elements of exert longitudinal forces thereto. A bracket pair is urged against the body of the device to be clamped while transverse forces are urged upon the wedge elements when the clamp is in its expanded state. When in its relaxed state, the clamp may be easily removed from the channels in which it is to be secured.

Abstract: The present disclosure illustrates that the process of summing an amplitude limited PSK (phase-shift keyed) signal with a one data bit delayed version of that signal and envelope detecting the sum will produce a digital binary data stream that is representative of the original data used to produce the PSK signal in the first place. This approach is distinguished over the prior art approach in that the PSK signal is limited to an amplitude value which is less than the minimum value produced by vectorial summation of noise with the transmitted PSK signal for optimal bit error rate performance.

Abstract: A broadband PIN diode transmit/receive switch. The switch is used for electrically coupling a single antenna alternately to a transmitter and to a receiver. A first PIN diode for switching is connected between the antenna and an output port of a second order network, an input port of the second order network being connected to an output of the transmitter. A tuned tank circuit has an input port connected to the antenna and has an output port connected to an input of the receiver. A second PIN diode for switching is connected from the output port of the tuned tank circuit to an RF ground. A DC source controls the PIN diodes. When both diodes are forward biased the transmitter is connected to the antenna and is provided a good impedance match over a substantial bandwidth, otherwise the receiver is connected to the antenna.

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: The present invention is a method and apparatus for providing an output signal having a high average power and the method has the steps of providing a standard frequency; forming a plurality of input signals from the standard signal such that each of the input signals has a predetermined frequency which is different from the frequencies of the other input signals; phase shifting at least one of the input signals such that at least one of the input signals has a phase different from the phase of the other input signals; combining all of the input signals to produce a combined signal; and amplifying the combined signal to produce the output signal. In one embodiment all of the input signals are phase shifted relative to one another and in another embodiment all of the input signals are equally phase shifted relative to one another except for one which is of opposite phase. Also all of the input signals are equally spaced in frequency relative to one another or have a common divisor in spacing.

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.