Abstract: A method of producing a thermally stable grating allows the grating to be placed in environments where temperatures reach 1000° C. These gratings may be concatenated so as to form a sensor array. The method requires a step of lowering the characteristic intensity threshold of a waveguide by at least 25%, followed by irradiating the waveguide with femtosecond pulses of light having a sufficient intensity and for a sufficient duration to write the grating so that at least 60% of the grating remains after exposures of at least 10 hours at a temperature of at least 1000° C. Pre-writing a Type I grating before writing a minimal damage Type II grating lowers the characteristic threshold of the waveguide so that a stable low damage type II grating can be written; alternatively providing a hydrogen or deuterium loaded waveguide before writing the grating lowers the characteristic threshold of the waveguide.

Abstract: The invention relates to a method and apparatus for acquiring a complex spreading code of a direct sequence spread spectrum signal (DSSS) by acquiring a state of a spreading code generator capable of generating the complex spreading code. A sequence of bipolar differential product values, which sign is independent on data transmitted by the DSSS signal, is obtained by combining in-phase and quadrature samples of the DSSS signal for adjacent chip intervals. This sequence is provided to a linear block decoder for obtaining a codeword of a linear block code, which is defined by a structure of the spreading generator and the differential product operation. The codeword is used to compute the state of the spreading code generator.

Abstract: A system has a first transmitter for transmitting a first wireless signal within a first frequency. A second transmitter is for transmitting a second wireless signal with overlapping frequency. The first transmitter and the second transmitter are disposed sufficiently proximate to another such that the wireless signals substantially interfere resulting in a combined wireless signal with negative SNR for each of the first wireless signal and the second wireless signal, the negative SNR being a result of at least the other of the first wireless signal and the second wireless signal. A receiver is located for receiving a received wireless signal comprising substantially interfering encoded data signals having negative SNR. The receiver is for selecting from the substantially interfering encoded data signals a signal of interest and for decoding said signal of interest relative to at least the other substantially interfering data signal within the received wireless signal.

Abstract: A method of producing a thermally stable grating allows the grating to be placed in environments where temperatures reach 1000° C. and where the grating is relatively stable and has very low loss from scatter. These gratings have spectral characteristics that allow them to be concatenated so as to form a sensor array. The method requires a step of lowering the characteristic intensity threshold of a waveguide by at least 25%, followed by irradiating the waveguide with femtosecond pulses of light having a sufficient intensity and for a sufficient duration to write the grating so that at least 60% of the grating remains after exposures of at least 10 hours at a temperature of at least 1000° C.

Abstract: The invention relates to receivers and methods for receiving multi-carrier differentially modulated signals utilizing iterative decision-directed differential detection. The receiver includes a decision feedback loop including a channel estimator for estimating inter-symbol channel variations, and a differential equalizer for correcting channel-induced errors in a differentially detected signal based on the estimated inter-symbol channel variations.

Abstract: The invention relates to a method and a graphical user interface for modifying a depth map for a digital monoscopic color image. The method includes interactively selecting a region of the depth map based on color of a target region in the color image, and modifying depth values in the thereby selected region of the depth map using a depth modification rule. The color-based pixel selection rules for the depth map and the depth modification rule selected based on one color image from a video sequence may be saved and applied to automatically modify depths maps of other color images from the same sequence.

Abstract: The invention relates to a method and an apparatus for reducing blocking artifacts in block-wise coding of still and video images. A learning filter generator is provided at the image encoder for generating a set of filters and associated filtering rules for filtering cross-boundary image patterns based on representative original and decoded training images using a supervised machine learning algorithm. An adaptive filter at the image decoder receives the generated filters and associated filtering rules and performs locally adaptive filtering in accordance with the received filtering rules.

Abstract: A waveguide bandpass filter for use in microwave and millimeter-wave satellite communications equipment is presented. The filter is based on a substrate integrated waveguide (SIW) having several cascaded oversized SIW cavities. The filter is implemented in a printed circuit board (PCB) or a ceramic substrate using arrays of standard metalized via holes to define the perimeters of the SIW cavities. Transmission lines of a microstrip line, a stripline or coplanar waveguide are used as input and output feeds. The transmission lines have coupling slots for improved stopband performance. The filter can be easily integrated with planar circuits for microwave and millimeter wave applications.

Abstract: An antenna steering mount includes two basic building blocks which are joined together to form any of the known steering-axis combinations. Each block includes a cylinder cut at an angle to form a cylindrical wedge. The wedges are joined together by bearings at their interface, and motors are used to counter rotate the two wedges relative to each other. One end of the complete assembly is attached to a mounting platform, and the other end includes mounting features for attaching an antenna dish thereto. Various two- and three-axis steering configurations are disclosed including combinations of azimuth, elevation, cross-elevation, and cross-level steering.

Abstract: An iterative channel estimation and inter-carrier interference (ICI) cancellation process is provided for OFDM receivers, and more particularly for mobile OFDM receivers. The iterative process uses decision feedback to estimate both the channel gain and the ICI gains, the latter being the multiplicative gain applied to the adjacent sub-carriers. Thus the receiver performs equalization and ICI cancellation in an iterative fashion and is advantageous for estimating fast fading channels.

Abstract: The invention provides a method and device for iterative hybrid time-frequency domain block equalization of signals received via a communication channel subject to multipath interference. The equalization method includes frequency-domain equalization of blocks of received signals in a forward path, and time-domain inter-block echo correction and intra-block cyclic echo addition in the feedback path. The invention can be used for equalizing signals transmitted without cyclic prefix and subjected to multi-path interference with long delay spread.

Abstract: The invention provides a distributed back-up mechanism and a two-step method for facilitating fast control plane recovery in a switched network. In a preferred embodiment, a Label Information Database (LID) maintained at a control node of a GMPLS network is mirrored to an upstream node using the Label Distribution Protocol (LDP). After a control plane interruption resulting in the LDP restart, the control node, using the mirrored information at the upstream node, conducts first a fast coarse LID recovery wherein only the idle labels are identified, to enable the restarted LDP session to process new connection setup. A detailed LDP state information recovery performs in the background in parallel to the normal LDP operations, e.g. using on-demand LDP queries.

Abstract: The invention relates to an encoding system and method for generating concatenated codes which utilize interleaving and data puncturing. The method includes selecting first and second puncture location sets defining desired puncture locations in non-interleaved and interleaved data sequences, respectively. A puncture-constrained interleaver is provided, which permutes the first puncture location set into the second puncture location set, so as to provide desired regular puncture patterns for all constituent codes. In a preferred embodiment, the puncture-constrained interleaving alters a symbol location relative to a puncture mask so as to satisfy a pre-defined spread or distance constraint.

Abstract: The invention provides a type-based method to compensate for distortions in circuits operating on a plurality of input modulated signals to form one or more output modulated signals. Steps of the method include low-rate sampling of the output signal to obtain a statistical characteristics thereof, and adjusting parameters of the circuit to introduce a controlled degree of cross-coupling between the signals until the statistical characteristics of the output signal approximates a reference characteristics defined by the used modulation formats. Another aspect of the invention provides a self-calibrating multi-port circuit implementing the method.

Abstract: The invention relates to methods and circuits for compensating linear in-band distortions such as those occurring in RF circuits of broad band communication systems. A low-rate sampling is used to collect statistical information about a modulated signal after it passed through the distorting circuits, which is then compared to reference statistical information for the modulated signal to iteratively adjust a frequency response of an equalizing linear filter inserted into the signal path so as to compensate for the distortions.

Abstract: A method of inducing birefringence in an optical waveguide is disclosed wherein the waveguide cladding is irradiated with energy of a sufficient intensity so as to induce a stress in the optical waveguide so as to cause a multitude of spaced stress induced regions within the cladding of the optical waveguide such that there are 10 to 5000 spaced regions per mm and wherein the stress induced regions are proximate the core greater than 2 microns distance from the core-cladding interface. This waveguide has numerous uses, for example a fiber sensor.

Abstract: The invention relates to a method of non-coherent decoding an encoded CPM signal received by a wireless receiver, and a CPM decoder implementing the method, wherein the signal is generated by a transmitter using a serial concatenation of an outer encoder, an interleaver and an M-ary CPM modulator, and may have a frequency-hopping RF carrier. In a preferred embodiment, the method includes iteratively decoding the received signal by first recursively finding a sub-set of dominant sequences of CPM symbols that maximize a path metric for one hop interval using a non-coherent CPM detector, determining on the basis of this sub-set a sequence of soft inner bits, decoding these soft inner bits with an outer decoder, and using extrinsic information for the soft inner bits provided by the outer decoder to iteratively update the sub-set of dominant sequences of CPM symbols in the inner CPM detector.

Abstract: A device for providing an expanded mode field from a single mode optical waveguide is formed by fusing a length of single mode optical fiber with a length of fiber rod absent a cladding and adiabatically tapering the fused region. The length of single mode fiber has a core having a refractive index nco and a cladding having a refractive index ncl, wherein ncl<nco and wherein the cladding has an outer diameter ?. The length of fiber rod absent the cladding has a refractive index of the fiber rod is substantially the same as the cladding index ncl of the single mode optical fiber. The outer diameter of the length of fiber rod is ?, the same as the cladding diameter of the single mode fiber.

Abstract: A method and system for communication of information in OFDM format are disclosed. The method employs multi-symbol encapsulation (MSE), wherein multiple OFDM symbols are grouped together in cyclic frames having a single cyclic guard portion, for example a cyclic prefix, with multiple OFDM symbols sandwiched between each two consecutive cyclic guard portions. All OFDM symbols of one frame are equalized together at the receiver in a frequency domain using a single DFT/IDFT operation sequence. Embodiments of the MSE OFDM system are disclosed enabling high bandwidth efficiency, high tolerance to carrier frequency offset and low peak-to-average power ratio.

Abstract: The invention relates to improving the performance of sequence-based soft-output decoders using event cleanup processing, wherein combinations of potential error events are evaluated using an error detection code (EDC) to select events that produce a modified set of decisions that has no EDC detectable errors. The event cleanup method and associated event cleanup decoder enable to significantly improve the error rate performance of sequence-based decoders and/or significantly improve decoding efficiency compared to other known error cleanup methods.