Abstract: Adaptive cooperative web caches construct and maintain routing and forwarding tables for efficient location of replicated web content data, thus reducing the time taken to fetch the requested web content data. The routing and forwarding tables in particular store decomposed web content identifiers and use compression techniques for efficient translation from a user request to the internet protocol address of the cache server where the replicated web content data can be retrieved.

Abstract: Polymer nanofibers, such as polyaniline nanofibers, with uniform diameters less than 500 nm can be made in bulk quantities through a facile aqueous and organic interfacial polymerization method at ambient conditions. The nanofibers have lengths varying from 500 nm to 10 ?m and form interconnected networks in a thin film. Thin film nanofiber sensors can be made of the polyaniline nanofibers having superior performance in both sensitivity and time response to a variety of gas vapors including, acids, bases, redox active vapors, alcohols and volatile organic chemicals.

Abstract: A turbo coded communication system includes a gray scale mapper in a transmitter for generating a symbol constellation of modulated signals points that can be separated by boundary lines in the constellation space into bitwise groups of zero bits and one bits where the shortest distance from a boundary line to received value in the constellation space indicates the bitwise soft metrics that is computed using a set of bitwise soft metric equations are a function of the minimum distance using closed form algebraic equations in turbo decoding receiver. In the case of quadrature amplitude modulation (QAM), the bit boundary lines are predetermined by a minimum distance in the constellation space for a specified M-ary modulation, so that, the soft metric equations are only a function of the received signal value for providing efficient computation of the bitwise soft metric.

Abstract: A turbo coded communication system includes a gray scale mapper in a transmitter for generating a symbol constellation of modulated signals points that can be separated by boundary lines in the constellation space into bitwise groups of zero bits and one bits where the shortest distance from a boundary line to received value in the constellation space indicates the bitwise soft metrics that is computed using a set of bitwise soft metric equations are a function of a minimum angle using closed form algebraic equations in turbo decoding receiver. In the case of phase shift keying (PSK) modulation, the bit boundary lines are predetermined by a minimum angle in the constellation space for a specified M-ary modulation, so that, the soft metric equations are only a function of the received signal value for providing efficient computation of the bitwise soft metric.

Abstract: A code division multiple access (CDMA) communication system using spread spectrum signaling over a communication bandwidth uses two different signal spectra generated using two different respective spreading code formats, such as NRZ code formatting and Manchester code formatting, for respectively providing nonsplit spectra having a center peak and split spectra having a center null. The spectra are combined during transmission as a CDMA communication signal having a composite spectrum. The use of different code formats produces the composite spectrum of respective center peak and center null spectra that enables increased channel capacity.

Abstract: The hybrid active combiner and circulators serves as a coupler and is a three port network that integrates a directional coupler topology with active devices placed in the coupling paths in order to synthesize a low-loss active combiner circuit or a circulator device with minimal insertion losses. The coupler can have multiple stage amplifiers with transconductance values set according the Pascal's triangle for improved performance, and can function as a low cost and low weight transceiver well suited for various communications systems.

Abstract: A civil moderate (CM) code and a civil long (CL) code are time division multiplex (TDM) as a combined code having alternating code chips that spectrum spread a transmitted signal received by a receiver tracking the spectrum spreading code using a two-level correlator operating with +1 and ?1 values to alternately correlate the received CM and CL code chips using a gating signal to gate by time the correlation of the two codes. The time gated two-level TDM correlation can be used in communication receivers, such as GPS receivers, receiving the TDM spectrum spreading codes.

Abstract: An nth root transformation is used for generating near Gaussian metrics from non-Gaussian metrics for input into a conventional turbo decoder that is based on the assumption that the input sequence to the decoder has a Gaussian distribution. The nth root transformation transforms channel non-Gaussian statistics to near Gaussian statistics for use with conventional turbo decoding for improved noncoherent communications over a non-Gaussian channel, such as a fading channel. For a differential coherent PSK waveform, where the channel statistics of a demodulator are non-Gaussian, for example, in the presence of fading, the nth root transformation is used to transform the non-Gaussian statistics to near Gaussian statistics for generating near Gaussian metrics, for improved PSK communications.

Abstract: A coherent adaptive subcarrier modulation system applies subcarrier modulation to quadrature modulated signals with constant envelope modulation suitable for efficient sinewave and squarewave subcarrier modulations. The quadrature subcarrier enables the addition of new signals to the in-phase and quadrature phase signals with spectral isolation in the Global Position System while maintaining a constant envelop amplitude.

Abstract: A generalized radix-2 block transform method enables true split and merge transform processing of equal sized data halves in the transform domain enabling recursive merges and splits in transform domain data degradation. Input data in the time domain or spatial domain during either the split and merge radix-2 forward transform processing is firstly transform processed followed by combinational processing. Whole transformed data is split using combinational processing into transformed data halves in the transform domain as a true split. The transformed halves are merged using combinational processing into whole merged transformed data in the transform domain. Time or spatial domain input data can be transformed into the transform domain in the form of split halves or merged whole. The split halves can be merged by the merge process combinational processing and the merged whole can be split by the split process combinational processing.

Abstract: Fast Fourier Transforms in a radix-2 block transform method enables true split and merge transform processing of equal sized data halves in the Fourier transform domain for enabling recursive merges and splits in Fourier transform domain without data degradation. Input data in the time domain or spatial domain during either the split and merge radix-2 forward transform processing is firstly transform processed followed by combinational processing. Whole transformed data is split using combinational processing into transformed data halves in the transform domain as a true split. Transform halves are merged using combinational processing into whole merged transformed data in the transform domain. Time or spatial domain input data can be transformed into the transform domain in the form of split halves or merged whole. The split halves can be merged by the merge process combinational processing and the merged whole are split by the split process combinational processing.

Abstract: An intermodulation suppression method using phased array antenna electronics insignificantly degrades the desired primary main beams while substantially suppressing undesired intermodulation product beams, and particularly undesired third-ordered intermodulation product beams. The beam smearing method has two aspects, including phase smearing and angle smearing for respective subarrays to reduce the intermodulation-product beams of the phased array antenna beam patterns. With a 1 dB degradation of the primary main beams, a 6 dB to 10 dB suppression of the intermodulation product beams is achieved.

Abstract: An optical system couples laser light into an optical fiber, such as a optical amplifier fiber, from the side of the fiber by side-pumping of the fiber that is in contact with the laser such that refracted laser light is redirected into and through the fiber using direct attachment of a laser, such as a high-power laser diode, to the inner cladding of a fiber.

Abstract: A premodulation precoding method precodes a data sequence in a Gaussian minimum shift keying (GMSK) modulator to improve the bit error rate performance of a coherent Viterbi receivers generating estimates of the communicated data sequence without the use of differential decoding while preserving the spectrum of 2-ary and 4-ary GMSK signals over a wide range of bandwidth time products.

Abstract: A transmission line analog-to-digital converter uses an unterminated transmission line driven by a current source to generate a stair-step waveform having equal time step periods for measuring the conversion time as a digital output value of an analog input. The converter has the advantages of simplicity, accuracy, high speed, low transistor count, and low power consumption. Fast successive approximation converters can be used for improved speed and accuracy of digital conversion of analog signals.

Abstract: A multispectral selective reflection Lidar system generates alternating pulses of at least two wavelengths and senses returns for determining the presence of a predetermined material absorbing and reradiating one wavelength as selective reflections, but not the other. A detector can readily determine the presence or absence or an absorbing and reradiating return. The system is for preferred use as an orbiter sensor about a planetary body, such as a Jupiter moon, for determining the presence of organic material and for the relay of information back to earth.

Abstract: A phased array antenna system divides the array into a plurality of subarrays that are driven by fine phase shifters with each subarray having a plurality of antenna elements driven by respective coarse phase shifters that are preferably MEMS coarse phase shifters having low weight and low cost and are infrequently used for improved reliability for selecting a coarse beam coverage area while the fine phase shifters are used to scan a high-gain antenna pattern within the selected coarse beam coverage area. Two-bit MEMS phase shifters are used to scan the beams from subarrays to various coverage areas within the required antenna field of view, thereby providing coarse beam steering for an array.

Abstract: Fast Hartley Transforms in a radix-2 block transform method enables true split and merge transform processing of equal sized data halves for enabling recursive merges and splits in Hartley transform domain without data degradation. Input data in the time domain or spatial domain during either the split and merge radix-2 forward Hartley transform processing is firstly transform processed followed by combinational processing. Whole transformed data is split using combinational processing into transformed data halves in the Hartley transform domain as a true split. The transformed halves are merged using combinational processing into whole merged transformed data in the Hartley transform domain. Time or spatial domain input data can be transformed into the Hartley transform domain in the form of split halves or merged whole. The split halves can be merged by the merge process combinational processing and the merged whole can be split by the split process combinational processing.

Abstract: Discrete Sine Transforms in a radix-2 block transform method enables true split and merge transform processing of equal sized data halves in the DST transform domain for enabling recursive merges and splits in DST transform domain without data degradation. Input data in the time domain or spatial domain during either the split and merge radix-2 forward transform processing is firstly transform processed followed by combinational processing. Whole transformed data is split using combinational processing into transformed data halves in the transform domain as a true split. The transformed halves are merged using combinational processing into whole merged transformed data in the transform domain. Time or spatial domain input data can be transformed into the transform domain in the form of split halves or merged whole. The split halves are merged by the merge process combinational processing and the merged whole are split by the split process combinational processing.

Abstract: Discrete Karhunen-Loeve Transforms in a radix-2 block transform method enables true split and merge transform processing of equal sized data halves in the KLT domain for enabling recursive merges and splits in the KLT domain without data degradation. Input data in the time domain or spatial domain during either the split and merge radix-2 forward transform processing is firstly transform processed followed by combinational processing. Whole transformed data is split using combinational processing into transformed halves in the transform domain as a true split. Transformed halves are merged using combinational processing into whole merged transformed data in the transform domain. Time or spatial domain input data can be transformed into the transform domain in the form of split halves or merged whole. The split halves are merged by the merge process combinational processing and the merged whole are split by the split process combinational processing.