Abstract: A method and apparatus for estimating a frequency of a received carrier wave in a Quadrature Phase Shift Keying (QPSK) system. The invention uses a combination of an FFT, DFT bins, and three point interpolation to estimate a frequency of the carrier wave. The system is robust and compensates for multipath fading and other types of signal degradation.

Abstract: A cryogenic bypass current lead to bypass quenched magnets in a string of magnets in a superconducting super collider comprises a HTSC section interposed between a lower conductive body terminal and the conductive of the lead is described.

Abstract: A broadcasting method for simultaneously broadcasting analog and digital signals in a standard AM broadcasting channel is provided by: broadcasting an amplitude modulated radio frequency signal having a first frequency spectrum, wherein the amplitude modulated radio frequency signal includes a first carrier modulated by an analog program signal; and simultaneously broadcasting a plurality of digitally modulated carrier signals within a bandwidth which encompasses the first frequency spectrum, each of the digitally modulated carrier signals being modulated by a portion of a digital program signal, wherein a first group of the digitally modulated carrier signals lying within the first frequency spectrum are modulated in-quadrature with the first carrier signal, and wherein second and third groups of the digitally modulated carrier signals lie outside of the first frequency spectrum and are modulated both in-phase and in-quadrature with the first carrier signal.

Abstract: The output matching networks normally included in a microwave power transistor package as well as the transistor combining network therefor are eliminated for heating applications, e.g. microwave ovens. In a preferred embodiment, the transistor dies of four microwave silicon bipolar power transistors are directly connected to the low impedance points of a common patch type antenna element, also referred to as an applicator, located within the wall of a heating chamber in place of a magnetron. Each pair of power transistors are electrically spaced one half wavelength apart and are located transverse to each other on the antenna. The transistors are operated in pairs with a 180.degree. phase difference so that mutually orthogonal longitudinal modes are excited in the antenna. Moreover, the transistors are frequency modulated over their prescribed frequency band to eliminate standing waves in the load, i.e. the article or substance being heated or cooked.

Abstract: A silicon microwave monolothic integrated circuit device and method of fabricating having a high resistivity silicon substrate with a masking layer of low temperature silicon oxide, silicon nitride and polysilicon sublayers on a first area, and an epitaxial layer over the surface of the silicon substrate in a second area. The active devices are formed over the second area and the passive devices are formed over the first area.

Abstract: An airspace management system and method includes an alternate quick look mode display option which allows a user to designate a specific geographic region for display in a specified area on a display screen. Within this specified area, which can encompass a portion or all of the display screen, radar plot data is displayed for at least one aircraft for which input radar information is received. Symbols can be assigned to aircraft to differentiate friend and enemy aircraft; colors can be assigned to differentiate friend and enemy aircraft and plots; and radar-measured height information can optionally be displayed. In this quick look mode, near real-time positions for all aircraft within the quick look mode window are displayed, since selection of the quick look mode window bypasses normal time-consuming tracking information processing.

Abstract: A power supply for providing a symmetric drive for an AC electroluminescent (EL) display panel includes a single power supply which provides two voltage signal values of opposite polarity V.sub.pos,V.sub.neg to the panel's row drivers. The supply also corrects the difference between the two voltage signal values V.sub.pos,V.sub.neg as a function of the difference between the maximum column driver voltage value V.sub.col and its nominal value to reduce latent images on the display panel. By utilizing a single switching regulator to generate the opposite polarity row voltages V.sub.pos,V.sub.neg the circuit complexity and cost associated with providing a symmetric drive for an EL panel is reduced.

Abstract: A rotating antenna system subject to both tilt and translation forces includes first and second tilt sensors each having a pendulum assembly of a different length than the other sensor. The sensors provide identical output signals in response to a tilt, but different output signals in response to a translation of the antenna. Circuitry is provided for eliminating the effects of translation so as to obtain a tilt angle correction signal for correcting the radar height calculation.

Abstract: A low frequency sonar system for detecting buried cables and pipelines that includes at least three sub-bottom sonar beam projectors arranged athwarships, i.e. transverse to the central longitudinal axis of the system platform and a common receiver, the latter preferably being an arc focused device. The projectors are comprised of parametric transmitters, with the two outer projectors canted relative to the middle projector so that sonar return signals having a relatively narrow beamwidth are directed to the bottom and returned as a sequence of specular reflections along the length of sub-bottom targets to the common receiver. The transmission from the three parametric transmitters result in three spaced apart "hits" on the target which are displayed as a function of depth. Three detections in a row, i.e. at the same depth, provide an indication of a cable or pipeline buried beneath the bottom of a body of water.

Abstract: A system for identifying the location of an aircraft on the surface of an airport includes a plurality of low power FM transmitters located along the boundaries of runway and taxiways. Each transmitter provides an FM signal having a common carrier frequency and each FM signal is encoded with unique information indicative of the position of the transmitter on the airport surface. Aircraft and other vehicles containing a conventional FM receiver "capture" only the strongest signal and process the "captured" signal to determine which transmitter was the source of the signal and hence where the aircraft is on the airport surface.

Abstract: A digital quadriphase-shift keying modulator is described which generates a modulated intermediate carrier frequency (IF) based on a desired number of samples for each input information bit. The design includes a ROM (or RAM) look-up table which stores digitized waveforms. The inphase and quadrature components of a complex baseband signal are translated to an IF at a multiple of the sampling rate simply by alternating the inphase and quadrature samples and alternating signs. The real IF output is produced by summing the inphase and quadrature signals.

Abstract: An AC thin film electroluminescent display panel includes a metal assist structure formed on and in electrical contact over each transparent electrode, and light absorbing darkened rear electrodes which combine to provide a sunlight viewable display panel.

Abstract: A microwave oscillator with loop frequency conversion to and signal amplification at an intermediate frequency. A high-Q sapphire dielectric resonator is coupled in a frequency conversion loop between a pair of balanced mixers. One mixer comprises a downconversion mixer from an output frequency F.sub.0 to an intermediate frequency F.sub.IF, while the other mixer comprises an upconversion mixer from the intermediate frequency F.sub.IF to the output frequency F.sub.0. The frequency conversion loop additionally includes a low 1/f noise IF amplifier coupled between the mixers. The two mixers receive a local oscillator signal having a frequency F.sub.0 .+-.F.sub.IF from a microwave reference signal generator. In such an arrangement, an output frequency section and an intermediate frequency section is provided. The output frequency section includes the sapphire dielectric resonator and an output power divider while the intermediate frequency section includes the two mixers and the IF amplifier.

Abstract: A modular mail processing method and control system for sorting pieces of incoming, internal, and outgoing mail including a plurality of sorting bins which correspond to either mail stops or zip codes depending on which sort plan is selected. The modular mail processing method and control system permitting mixed pieces of mail of various sizes to be sorted. Additionally, an internal mail envelope, which has address regions consisting of blocks, may be utilized in connection with the modular mail processing method and control system in order to allow accurate detection of handwritten addresses.

Abstract: A numerically controlled oscillator that outputs a complex exponential value (sine and cosine). The numerically controlled oscillator inputs a scalar phase increment and uses the scalar phase increment to approximate a complex exponential phasor increment. A complex multiplier multiplies the exponential increment by an exponential value previously output from the oscillator to yield a multiplication result. A recursive amplitude normalizer, connected to the complex multiplier, normalizes the multiplication result to yield the complex exponential value.

Abstract: A system for sensing images using a detector array and correcting errors in the image signals caused by gain and offset variations from detector to detector in the array is disclosed. To correct gain and offset errors, the detector array is dithered by moving the detector line of sight between consecutive frames according to a predetermined pattern. This dithering causes different detectors to image the same location in the scene during different frames, and causes two adjacent detectors to scan between the same two points in the scene during a cycle of the dither pattern. Image data generated from the dithering is used to remove gain and offset errors from the sensed images, and to generate gain and offset correction values to be stored in a table and applied to the sensed images. The system is also adapted to compensate for scene changes when the detector array is installed on a moving platform.

Abstract: An electric vehicle power distribution module including a chassis containing electric power distribution components. A battery connector is disposed on the chassis for electrically connecting the power distribution components to a battery. A safety cover is secured to the chassis and includes an aperature in a side wall for receiving an electric cable from the battery to be selectively engaged with the battery connector. The aperture is positioned with respect to the battery connector so as to preclude removal of the safety cover from the chassis without disengagement of the electric cable from the battery connector.

Abstract: A microprocessor-based system includes a central processing unit (CPU) and a CPU memory coupled by a CPU bus. A DMA sampler is coupled to the CPU, the CPU memory and the CPU bus. The DMA sampler includes sampling circuitry which is implemented as a finite state machine to maintain a substantially exact sampling rate on at least one analog input signal provided to the DMA sampler. The DMA sampler also includes DMA circuitry implemented as a data flow machine, which requests bus mastership from the CPU when samples obtained by the DMA sampler are available for transfer to the CPU memory. In response to the request, the CPU relinquishes bus mastership to the DMA sampler which provides the sample to the CPU memory and returns bus mastership to the CPU.

Abstract: A preconcentrator is provided for use in a solid state mass spectrograph for analyzing a sample gas. The mass spectrograph is formed from a semiconductor substrate and has a cavity with an inlet, a gas ionizing section adjacent the inlet, a mass filter section adjacent the gas ionizing section and a detector section adjacent the mass filter section. The preconcentrator is provided in the mass spectrograph between the inlet and gas ionizing section. The preconcentrator includes an array of preconcentrating elements, each of which is built upon a semiconductor substrate upon which a dielectric membrane has been deposited. An absorber is provided on the membrane for collecting and concentrating the gas to be sampled. Heater means provided on the membrane releases the absorbed sample gas from the absorber.

Abstract: A signal of bandwidth F.sub.max is unambiguously transmitted over a datalink having a bandwidth less than F.sub.max by subdividing the signal into a plurality of subspectrums and bandshifting the subspectrums greater than the datalink bandwidth to baseband. Each bandshifted subspectrum is uniquely encoded using a different pilot tone which can be detected by the receiver to decode the receive signal and unambiguously recover the narrowband spectrum components.