Abstract: A method for constructing and selecting non-recursive orthogonal variable spreading factor (OVSF) codes is provided. The method includes: defining a variable B=SFmax/SFmin, where SFmax is a maximum desired spreading factor and SFmin is a minimum desired spreading factor; forming B unique base matrices Gk of dimension SFmin×SFmin, where GiGiT=SFminImin ?i, where T denotes a matrix transpose and Imin is an SFmin×SFmin identity matrix; forming a modulation matrix M of dimension B×B such that MMT=BIB, where IB is a B×B identity matrix; forming an SFmax×SFmax orthogonal variable spread factor (OVSF) code matrix C? as: C ? = [ M 1 , 1 · G 1 M 1 , 2 · G 2 … M 1 , B · G B M 2 , 1 · G 1 M 2 , 2 · G 2 … M 2 , B · G B ? ? ? ? M B , 1 · G 1 M B , 2 · G 2 … M B , B · G B ] , where Mi,j is a scalar from the i-th row and j-th column of the modulation matrix M, Gl . . .

Abstract: A first node initiating communications with a second node already in a secure network sends a discovery burst having a preamble portion and a payload portion. The preamble portion is sent at a varying frequency between high and low thresholds that are reflective of Doppler uncertainty between the nodes. The second node continuously listens at a frequency, termed an acquisition frequency. A data sequence in the preamble portion, known to the second node, is received and used to determine the receive instant in the preamble portion, and thereby compare against the known frequency ramp to determine the frequency at which the payload portion will be received. Preferably, the first node varies the preamble portion between thresholds more than once within the time span of a single preamble portion, and the preamble and payload portions are spread with different spreading codes. The preamble portion may also be disguised with noise generated by the first node.

Abstract: A system and method for enabling transmission of a stepped-frequency radar signal can involve a first antenna and a second antenna. The system can also involve receiving circuitry configured to receive detected reflections from the antennas and to generate data including information associated with frequency and phase shifts. The system can further involve a processor configured to receive the generated data from the receiving circuitry and to analyze the generated data to determine information associated with a moving object located at a side of a wall opposite to the system by differentiating reflections of the transmitted signal detected with the first antenna from reflections of the transmitted signal detected with the second antenna.

Abstract: A first pulsed beam of charged particles from a particle accelerator is accelerated toward a first target that is configured to emit a fast neutron beam in response to being struck by an accelerated particle such that the fast neutron beam is directed toward a physical region. The last neutron beam includes a neutron having an energy sufficient to cause fission in a fissionable material. Data from a sensor configured to detect radiation of a fission product is accessed, and before accelerating a second pulsed beam of charged particles, whether the physical region includes a fissionable material based on the data from the sensor is determined.

Abstract: A system and method for detecting entities based on movement can involve transmission circuitry configured to enable transmission of a stepped-frequency radar signal, an antenna, and receiving circuitry configured to generate data including information associated with frequency and phase shifts between the transmitted signal and the reflections of the transmitted signal. The system also can involve a processor configured to analyze the generated data to determine information associated with a moving object located at a side of a wall different than a side of the wall of which the system is located. The analyzing can involve compensating for the effect of motion of the system on the phase shifts between the transmitted signal and the reflections of the transmitted signal.

Abstract: A parallel correlator and method includes temporarily storing in a series of P sequence registers, each of length R1, serial bit-sequences of a code of length N=P*R1. In a first-level of processing, certain unique bit sequences are inverted to reduce the number of unique bit sequences by half. Identical bit-sequences are then combined and temporarily stored in a first-level sub-accumulation register. Alternatively, bit sequences differing by only one bit may be combined in a common first-level sub-accumulation register. Further levels of similar processing may be imposed, where each subsequent level taps and inverts only a portion of the bits in the above level of processing, thereby reducing the number of unique bit sequences. Finally, all negative energy is combined in one register position, inverted, and added to all positive energy in the other register positions.

Abstract: The tracking of the phase of a received signal having a known preamble is accomplished by the steps of: initializing a phase-locked loop in accordance with estimated phase parameters, which are generated during an estimation interval by processing samples of the known preamble; delaying the preamble; generating phase error parameters by processing samples of the delayed preamble; and training the phase locked loop by tracking the phase-tracked signal in accordance with the tracking error parameters during a training interval after the estimation interval. The timing of the sampling is likewise trained in a closed timing loop in accordance with timing error parameters generated during the training interval after the timing loop has been initialized by estimated timing parameters generated during the estimation interval. The duration of the delay of the preamble is one-half the duration of the estimation interval.

Abstract: A method for operating an inspection system is disclosed in which an item under inspection may be moved between radiation sources and detectors illuminated by the sources. The radiation sources may be positioned such that radiation from at least some of the sources impinge on the radiation detectors, forming acute angles with respect to a plane having a normal direction coinciding with the first direction that are substantially in excess of three degrees. Data accumulated by the radiation detectors may be processed to form a three-dimensional tomographic data image of at least a portion of the item under inspection. The processing may be performed using an algebraic reconstruction technique using an inverse system matrix. The inverse matrix can be derived without first computing a transpose of the system matrix.

Abstract: A system may comprise a cathode, a target, one or more switches, and a conductive element. The cathode may be configured and arranged to generate an electron beam, and the target may be configured and arranged to emit radiation when electrons in the electron beam impact the target after being accelerated by an energy source. The one or more switches may be configured and arranged to apply either a first voltage or a second voltage from a power supply between the cathode and the target. The conductive element may be disposed between the cathode and the target so as to inhibit the electron beam generated by the cathode from reaching the target when a signal is applied to the conductive element.

Abstract: The exemplary embodiments of the invention provide techniques that assist in the absorption, reduction or elimination of the resonance of unwanted cavity modes in a cavity measurement system, such as a cylindrical TE0,n cavity measurement system used to measure various dielectric properties of a dielectric sample, for example. One non-limiting, exemplary system includes: sidewalls; a first endplate; a second endplate disposed opposite the first endplate so as to define a cavity bounded by the sidewalls, the first endplate and the second endplate; and first and second radio frequency (RF) coupling receptacles coupled to at least one of the sidewalls, the first endplate or the second endplate, wherein the first and second RF coupling receptacles are configured to pass a RF signal through the cavity. The first endplate has a plurality of conducting loops disposed on a surface facing the second endplate.

Abstract: Methods and systems for modeling concurrent behavior in a sequential programming environment using sequential-execution languages to describe and model multiple different processes which are running simultaneously.

Abstract: A system and method for determining a fine frequency offset of a composite code spread spectrum signal is disclosed. The method includes despreading at least one component of the composite spread spectrum signal to form a partially despread composite spread spectrum signal. A set of on-time samples are selected from the signal. The set of on-time samples are rotated by a predetermined frequency amount. The set of rotated samples are placed into a plurality of frequency bins, with each frequency bin representative of a different frequency estimate. An energy for the signal in each frequency bin is determined to find the bin having the greatest energy.

Abstract: The present invention relates to an apparatus that controllably allows the relative rotation between structures, such as a gimbal and a structure to which it is mounted. According to one aspect, the apparatus includes a twist capsule assembly with internal stop mechanisms that controllably prevents the amount of clockwise and counterclockwise rotation with respect to a rotation axis. According to another aspect of the invention, by limiting the amount of relative rotation, other means of communicating power and signals between the structures can be used, thus avoiding or reducing the limitations imposed by conventional slip ring assemblies. According to yet another aspect, the invention includes techniques and structures for allowing conventionally shielded cables and wires to be used in place of slip rings, while allowing for rotation between structures, thus even further improving the communication of power and signals between structures.

Abstract: A correlator despreads a P/N long code constructed from two or more constituent codes A, B, C having N, M and L elements respectively. In a third stage, L filter taps decorrelate elements of the third constituent code from the input received signal, leaving elements of code AB. The outputs of the third stage delay line are summed and input into a second stage delay line having M filter taps to decorrelate the elements of the second constituent code from the input to the second stage, leaving elements of code A. The outputs of the second stage delay line are summed and input to a first stage delay line having N filter taps. The output of the first stage delay line is summed and input into a shift register. An energy peak in the shift register indicates the phase of the P/N elements in the register is proper.

Abstract: A volumetric image of a space is acquired from an imaging system. The space includes an object of interest and another object, and the volumetric image includes data representing the object of interest and the other object. A two-dimensional radiograph of the space is acquired from the imaging system. The two-dimensional radiograph of the space includes data representing the object of interest and the other object. The two-dimensional radiograph and the volumetric image are compared at the imaging system. A two-dimensional image is generated based on the comparison. The generated two-dimensional image includes the object of interest and excludes the other object.

Abstract: A technique for scheduling transmissions for a plurality of transmitters in a TDMA network is described. The technique includes assigning guard time between each pair of successive transmitters, where the guard time is related to the propagation delay between the pair of successive transmitters. Total guard time is minimized by selecting an order of transmission for the plurality of transmitters to minimize the total guard time.

Abstract: A piece of luggage, such as a suitcase, is constructed with one or more compartments of predesigned location and purpose to facilitate security inspection. Compartments may be designated to hold objects that, if obscured by other objects, carry an undesirably high likelihood of generating a false alarm because obscuring objects prevent an accurate assessment of the nature of those objects. For this reason, a compartment may be designated for liquids, gels and/or aerosols. A compartment may also be designated for objects, such as metal objects, which carry a risk of generating a false alarm if packed in a suitcase in a way that they obscure other objects and prevent an accurate determination of whether those objects are threat objects. Such compartments are positioned to ensure that the items they contain are segregated during x-ray inspection so as to neither obscure or be obscured by other objects packed in the luggage.

Abstract: A system displays video to a user and has a display device with a field of pixels. It displays video to the user in the form of a series of discrete sequential frame images each made up of a first predetermined number of bit planes in which the pixels of the display are either off or have a color and intensity that is uniform over the field of pixels. The apparatus detects when a movement condition is present, such as rapid head movement or an object in the video crossing the display rapidly, in which condition the user's eye may tend to track across the display device at a rate at which perception of the video displayed may be reduced in quality, and it generates a condition-present signal when such a movement condition is detected. Responsive to generation of said condition-present signal, the apparatus causes the display device to display the frame images using fewer bit planes for each frame image than when said movement condition is not detected.

Abstract: Systems and methods for providing a weighted overlap and add (WOLA) architecture and/or for providing polyphase WOLA FFT processing that may be employed, for example, for separation or channelization of closely-spaced frequencies of an input signal. A WOLA architecture that may be implemented as first-in-first-out (FIFO) cores in an FPGA or ASIC device. The FIFO cores may be pre-existing (e.g., provided as free FIFO cores in a commercial off the shelf (COTS) FPGA device) or may be custom-programmed into a custom ASIC device.

Abstract: A traveling-wave tube system and a method for protecting a cathode of a traveling-wave tube system. The system has an electron gun and a power supply that applies an electric potential between a cathode and an anode of the electron gun to generate a beam of electrons. The beam of electrons passes through a passage of a slow-wave structure. A collector electrode collects electrons from the beam of electrons generating a flow of current that flows through an ion trap power supply circuit to generate a DC voltage that is applied to the anode to repel positive ions generated.