1483 results about "Matched filter" patented technology

A transceiver for a RFID reader and a transceiver for a RFID transponder (tag) allow communication between the two devices. The RFID reader utilizes an analog front end and a digital backend. In the receiver portion of the transceiver, the front end of the RFID reader uses a pair of down-conversion mixers to demodulate a received signal into in-phase (I) and quadrature (Q) components and analog-to-digital converters (ADC) digitize the signal. A digital signal processor (DSP) in the back end processes the digital signal and uses a matched filter for data detection. The RFID tag receives an inductively coupled signal from the reader and the receiver portion of the tag uses a pulse / level detector that employs an analog comparator and a sample and hold circuit to detect the received signal. A digital decoder / controller is used to decode the incoming data and to establish a sampling clock for the pulse / level detector. An automatic gain control (AGC) circuit adjusts a receiver gain according to the received signal strength and controls tuning of magnetic coupling circuitry.

A method and apparatus is provided for detecting a pulse in a signal. In one aspect of the invention, a method comprises digitizing the signal into a plurality of samples; repeatedly convolving each one of at least a portion of the buffered samples R times, wherein R>1; and detecting the received signal's center of energy from the convolution results. In a second aspect, an apparatus comprises a analog-to-digital converter capable of digitizing the received signal to produce a plurality of samples; a convolution circuit, including a matched filter for convolving the digitized signal at a second sampling rate; a buffer capable of storing the samples and serially outputting each of the samples R times, where R>1, to the convolution circuit; and a detector for detecting the digitized signal's center of energy from the output of the convolution circuit.

A 3-dimensional sonar system having a fixed frame of reference including a transmitter and receiver array. The system may include a single ping processor for processing received echoes from a single transmission including methods to match filter sonar sensor data, to optionally compensate for self Doppler, beamform sonar sensor data, to extract bottom targets from beamformed data and to extract in-water targets from the beamformed data. The system may also include a multi ping processor to operate on the outputs of multiple pings from the single ping processor including methods to detect tracks from in-water targets.

In this patent, we present MultiCode Direct Sequence Spread Spectrum (MC-DSSS) which is a modulation scheme that assigns up to N DSSS codes to an individual user where N is the number of chips per DSSS code. When viewed as DSSS, MC-DSSS requires up to N correlators (or equivalently up to N Matched Filters) at the receiver with a complexity of the order of N2 operations. In addition, a non ideal communication channel can cause InterCode Interference (ICI), i.e., interference between the N DSSS codes. In this patent, we introduce new DSSS codes, which we refer to as the "MC" codes. Such codes allow the information in a MC-DSSS signal to be decoded in a sequence of low complexity parallel operations which reduce the ICI. In addition to low complexity decoding and reduced ICI. MC-DSSS using the MC codes has the following advantages: (1) it does not require the stringent synchronization DSSS requires, (2) it does not require the stringent carrier recovery DSSS requires and (3) it is spectrally efficient.

A novel and useful whitening matched filter (WMF) for use in a communications receiver. The WMF is constructed by cascading a matched filter and a noise-whitening filter. The response of the matched filter is derived from the time reversed complex conjugate of the channel impulse response. The whitening filter is derived by extracting the minimum phase portion of the mixed phase channel impulse response using homomorphic deconvolution. The whitening filter is implemented using either an FIR or IIR filter adapted to process the data received before and after the training sequence using a minimum phase system in a direction in time opposite to that of the direction of corresponding data sample processing performed by the equalizer.

A transceiver for a RFID reader and a transceiver for a RFID transponder (tag) allow communication between the two devices. The RFID reader utilizes an analog front end and a digital backend. In the receiver portion of the transceiver, the front end of the RFID reader uses a pair of down-conversion mixers to demodulate a received signal into in-phase (I) and quadrature (Q) components and analog-to-digital converters (ADC) digitize the signal. A digital signal processor (DSP) in the back end processes the digital signal and uses a matched filter for data detection. The RFID tag receives an inductively coupled signal from the reader and the receiver portion of the tag uses a pulse / level detector that employs an analog comparator and a sample and hold circuit to detect the received signal. A digital decoder / controller is used to decode the incoming data and to establish a sampling clock for the pulse / level detector. An automatic gain control (AGC) circuit adjusts a receiver gain according to the received signal strength and controls tuning of magnetic coupling circuitry.

Embodiments of the present invention relate to the detection of synchronization marks in data storage and retrieval. According to one embodiment, synchronization marks are detected from the output of a matched filter, upstream of the Viterbi detector. This approach avoids the delay associated with the latency of the Viterbi output, thereby allowing time to align parity framing and to properly start the time-varying trellis. Certain embodiments disclose 34- and 20-bit primary synchronization marks located at the beginning of a data region. Other embodiments disclose 16-, 20-, and 24-bit embedded synchronization marks located within a data region.

The recently introduced theory of Compressive Sensing (CS) enables a new method for signal recovery from incomplete information (a reduced set of “compressive” linear measurements), based on the assumption that the signal is sparse in some dictionary. Such compressive measurement schemes are desirable in practice for reducing the costs of signal acquisition, storage, and processing. However, the current CS framework considers only a certain task (signal recovery) and only in a certain model setting (sparsity).We show that compressive measurements are in fact information scalable, allowing one to answer a broad spectrum of questions about a signal when provided only with a reduced set of compressive measurements. These questions range from complete signal recovery at one extreme down to a simple binary detection decision at the other. (Questions in between include, for example, estimation and classification.) We provide techniques such as a “compressive matched filter” for answering several of these questions given the available measurements, often without needing to first reconstruct the signal. In many cases, these techniques can succeed with far fewer measurements than would be required for full signal recovery, and such techniques can also be computationally more efficient. Based on additional mathematical insight, we discuss information scalable algorithms in several model settings, including sparsity (as in CS), but also in parametric or manifold-based settings and in model-free settings for generic statements of detection, classification, and estimation problems.

The present invention relates to the conversion of signals from RF to baseband using transition functions, or edge functions. These functions typically transition from positive to negative, or from negative to positive, synchronously with the transition of the received pulse signal, effecting detection essentially by synchronously rectifying a signal cycle of the received pulse, producing a net signal at baseband that can be further processed to detect modulation according to the modulation format. It is further disclosed how to configure these systems for optimal reception with a filter optimized for a given detect signal function. Generalizations of the matched filter embodiment lead to further embodiments employing alternative detection functions. Also disclosed is a two-stage version which applies a decode signal to the rectified signal. This step can be performed by a single correlator or by a plurality of correlators in parallel. Coding methods are disclosed to employ two-stage systems for enhanced channelization, and interference rejection.

A waiting circuit which is utilized in a mobile communication system. The waiting circuit detects a predetermined signal from a base station. The waiting circuit starts other circuits in the mobile communication system which are in a sleep mode when the predetermined signal is received. The predetermined signal is generated in the base station. The predetermined signal has a speed equal to a predetermined symbol rate and is modulated to be an intermediate frequency signal. The intermediate frequency signal is sampled in response to a sampling clock that has a speed equal to an integer times the symbol rate. The sampled intermediate frequency signal is input to a match filter which multiplies the sample signal by a predetermined sequence of coefficients.

A device for detecting a demodulated signal received by a spread spectrum receiver and converted into digital samples. The device is characterized by a matched filter for calculating the correlation between an incoming signal and at least one reference signal, an oscillator for generating a sampling frequency, and a sampling circuit for re-sampling the demodulated digital sample signal at the sampling frequency, which is such that the timing of samples of the references signals of the matched filter corresponds to the timing of a sample signal going from the sampling circuit to the matched filter. The device also includes a multiplier in which the sample signal is multiplied by a carrier replica generated locally before the sampling circuit or thereafter, to remove the carrier from the sample signal.

In one aspect, a method of detecting at least on feature associated with a blood vessel in at least one image of at least one blood vessel using a matched filter adapted to respond to the at least one feature is provided. The method comprises applying a scale detection filter to selected voxels in the at least one image to determine a scale for the matched filter at each of the selected voxels, determining an orientation for the matched filter at each of the selected voxels, wherein determining the orientation is assisted by using the scale determined at each of the selected voxels, applying the matched filter at each of the selected voxels at the scale and the orientation determined at each of the selected voxels to obtain a filter response at each of the selected voxels, and analyzing the filter response at each of the selected voxels to determine if the respective voxel corresponds to the at least one feature.

A receiver for spread spectrum communication system receives a traffic channel and common control channel by a plurality of matched filters at least one of which is selectively available for the traffic or the common control channel. At the initial acquisition, a plurality of matched filters are used for receiving the common control channel. At the hand-over, a plurality of matched filters are used to receive traffic channels of the current base station and the base stations in the adjacent cells.

Signals detected by particle motion sensors in a towed dual sensor marine seismic streamer are scaled to match signals detected by pressure sensors in the streamer. The pressure sensor signals and the scaled particle motion sensor signals are combined to generate up-going and down-going pressure wavefield components. The up-going and down-going pressure wavefield components are extrapolated to a position just below a water surface. A first matching filter is applied to the extrapolated down-going pressure wavefield component. The filtered down-going pressure wavefield component is subtracted from the extrapolated up-going pressure wavefield component, generating an up-going pressure wavefield component with attenuated particle motion sensor noise. A second matching filter is applied to the extrapolated up-going pressure wavefield component. The filtered up-going pressure wavefield component is subtracted from the extrapolated down-going pressure wavefield component, generating a down-going pressure wavefield component with attenuated particle motion sensor noise.

A real time fingerprint verification system includes a recording device and a verification device each having a fingerprint scanner for generating a flat, dimensionally undistorted, high contrast, fingerprint image, and an intensity sensitive, spatial light modulator (SLM) for receiving and transforming the flat fingerprint image into a planar, coherent light image. In the recording device, the planar coherent light image beam of the fingerprint from the SLM is Fourier transformed, and input into a microscope objective lens system which expands the Fourier transformed beam image sufficiently to allow mechanical blocking of its central portion or order, whereupon it is directed to interact as an object beam with a reference beam from the particular coherent light source to record a holographic matched filter. In the verification device, the planar coherent light image beam of the fingerprint is Fourier transformed and input into a microscope objective lens system to allow similar mechanical blocking of its central portion or order whereupon it is directed to interrogates a previously recorded holographic matched filter of a fingerprint image as an object beam for determining a match or not between the respective recorded and interrogating images. The spatial light modulator (SLM) in both the respective recording and verification devices enables phase correlation (optical path length determination) of one device to another device. X-Y alignment and rotational orinentation of the respective real time image and holographic matched filter image is accomplished by jittering (orbiting and angularly oscillating) either the interrogating object beam, real time, relative to the matched filter or visa versa.

Direct detection of wireless interferers in a communication device for multiple modulation types. One or more radios implemented within a communication device is / are operative to receive and process wireless communications. A wireless communication signal is processed to extract symbols there from. Various symbols groups are processed in accordance with correlation processing to identify potential interferers (e.g., other communication devices using common portions of frequency spectra). Alternatively, matched filter processing (e.g., using a Barker matched filter in some embodiments) operates on the various symbol groups to identify some potential interferers. Various combinations of correlation processing and matched filter processing may be employed in other instances (e.g., using any of a desired means of comparison, combining, etc.) in considering interferers identified in accordance with each of these two means. Also, re-identification and re-characterization of possible interferers may be performed subsequently to remove or re-admit frequency spectra for use in communications.

A multistage adaptive parallel interference canceller is disclosed. The multistage adaptive parallel interference canceller for a downlink receiver includes: a plurality of stages of interference cancellation units. Each of interference cancellation units includes: a matched filter for matching a signal from a rake receiver each channel signal and generating a matched signal; a soft decision unit of which a slope is monotonically increased, for performing soft decision of the matched signal and generating a soft-decided signal; a weight controller for controlling the slope of the soft decision unit; a respreader for respreading the soft-decided signal based on a walsh code and a scrambling code and generating a respread signal; an interference calculator for calculating interference signals due to another user signal and multipath signals; and an interference canceller for canceling the interference signals from an input signal received in the rake receiver.

The present invention relates to an ultrasound imaging system in which the scan head includes a beamformer circuit that performs far field subarray beamforming or includes a sparse array selecting circuit that actuates selected elements. When using a hierarchical two-stage or three-stage beamforming system, three dimensional ultrasound images can be generated in real-time. The invention further relates to flexible printed circuit boards in the probe head. The invention furthermore relates to the use of coded or spread spectrum signalling in ultrasound imaging systems. Matched filters based on pulse compression using Golay code pairs improve the signal-to-noise ratio thus enabling third harmonic imaging with suppressed sidelobes. The system is suitable for 3D full volume cardiac imaging.

A digital passband matched filter is automatically adapted to a carrier wave ω in accordance with a frequency offset of the carrier wave, to obtain a passband digital signal having no frequency distortion due to the frequency offset. Thus, a receiver in which drawbacks such as decrease of SNR and increase of circuit complexity caused by the fixed baseband / passband matched filter is obtained. Since a cosine wave generating section operates in a carrier wave frequency restoring mode and a carrier wave frequency adaptive mode, respectively, a single cosine wave ROM table can be used regardless of the respective operating modes, thereby reducing circuit complexity. Since the digital passband matched filter acts to renew the filter coefficients adapted to the carrier wave adaptive mode only, power consumption required to operate the filter can be minimized.

A hard disk drive (HDD) holds data using a biphase scheme. A plurality of matched filters are used to detect binary data represented by the biphase pattern without the need for synchronous sampling or equalization.

A cancellation system may utilize a system architecture that delays the received signals and cancels less than all the received signals from the delayed version of the received signals. An implementation of this system architecture may include a delay circuit, a demodulation and despreader unit, a re-modulator and re-spreader unit and a combiner. The delay circuit produces a delayed version of the received signals and the demodulator and de-spreader unit produces a demodulated and de-spread signal corresponding to one of the received signals. The respreader and remodulator unit produces a remodulated and respread signal from the demodulated and despread signal and the combiner produces a combined signal from the delayed version of the received signals and the remodulated and respread signal. The cancellation system may also utilize a system architecture that stores the received signals and cancels less than all the received signals from the stored version of the received signals. An implementation of this system architecture may include a matched filter, a storage unit, a remodulator and respreader unit, and a combiner. The storage unit stores the received signals and the matched filter produces a demodulated and despread signal corresponding to one of the received signals. The remodulator and respreader unit produces a remodulated and respread signal from the output of the matched filter and the combiner produces a combined signal from the output of the storage unit and the remodulated and respread signal.

A transceiver for a RFID reader and a transceiver for a RFID transponder (tag) allow communication between the two devices. The RFID reader utilizes an analog front end and a digital backend. In the receiver portion of the transceiver, the front end of the RFID reader uses a pair of down-conversion mixers to demodulate a received signal into in-phase (I) and quadrature (Q) components and analog-to-digital converters (ADC) digitize the signal. A digital signal processor (DSP) in the back end processes the digital signal and uses a matched filter for data detection. The RFID tag receives an inductively coupled signal from the reader and the receiver portion of the tag uses a pulse / level detector that employs an analog comparator and a sample and hold circuit to detect the received signal. A digital decoder / controller is used to decode the incoming data and to establish a sampling clock for the pulse / level detector. An automatic gain control (AGC) circuit adjusts a receiver gain according to the received signal strength and controls tuning of magnetic coupling circuitry.

A matched filter is configured for matching an input signal to a plurality of programmable-length complementary Golay-code pairs. The matched filter includes a sequence of delay elements configured for delaying the input signal with respect to at least one delay vector. A sequence of programmable seed vector insertion elements is configured for multiplying the input signal and delayed versions of the input signal by a set of seed-vector values. At least one of the seed-vector values may be set to zero to facilitate processing Golay codes having different lengths.

Codes to be detected can be identified at high speed. The supply of the data shift clock (DCLK1) to be given to the matched filter (82) is stopped at desired timing to hold the received signal (S10) and replica code generated at the correlation coefficient generator (83) is switched to the first, second or third replica code at desired timing to detect the correlation value of that time. Thereby, the second code, the third code and the first code are detected in order to detect the timing and the code type of the first code. Therefore, each correlation detection can be conducted at the same timing since the matched filter conducts the correlation detection at high speed holding the received signal and thus, the first code included in the received signal can be identified at higher speed than before.

A data detection circuit within a global positioning system (GPS) satellite receiver operates to detect and decode data sent in a spread spectrum signal. The data detection circuit receives input from a radio receiver, the information containing data from a plurality of satellites. The data is supplied to a circular memory device, which determines which data corresponds to which satellite. The memory device sends the received signal to a matched filter, which decodes the signal received from each satellite. This signal is analyzed to determine whether a phase inversion due to data modulation on the received signal is present. The phase inversion can occur at boundaries, known as data epochs, in the received signal, and corresponds to data in the received signal. This data contains information relating to the position of each satellite and is collected by the data detection circuit for use by the GPS receiver.

A demodulation system for receiving and demodulating multiple modulated signals, including a first modulated signal having a first bit rate and / or a first modulation format and a second modulated signal having a second bit rate and / or a second modulation format. The demodulator demodulating the first modulation format modulated signal provides a cross-correlated demodulated in-phase and quadrature-phase baseband signal and the demodulator demodulating the second modulation format modulated signal provides a second demodulated baseband signal. A selector selects either the first or the second or both bit rate and / or modulation format demodulated baseband signals. In an alternative embodiment two demodulators are implemented for the demodulation of multiple signals. In certain embodiments the demodulator demodulating the first bit rate modulated signal or the second bit rate modulated signal is comprised of bit rate switchable filters and / or mis-matched filters which are mismatched to that of the filters of the modulator of the first or the second bit rate modulated signal. In some of the applications the first or the second modulated signal is an Orthogonal Frequency Division Multiplexed (OFDM) modulated signal and / or a spread spectrum modulated signal and / or Phase Shift Keying (PSK) modulation, or a Quadrature Modulation (QM), or a Frequency Modulation (FM) modulated signal. In certain implementations and applications the demodulator is used for demodulation of Gaussian Minimum Shift Keying (GMSK) modulated signals and spread spectrum modulated signals.

A polarimetric imaging system employs a pixel pitch matched filter for use within, for example, a 2 by 2 pixel neighborhood, in which one pixel samples the scene via a 0 degree polarization filter and a second pixel samples the scene via a 45 degree polarization filter. The remaining two pixels record the intensity of the light within the 2 by 2 neighborhoods. The polarization filters employ organic materials such as polymers or metallic materials that are patterned and etched using reactive ion etching (RIE) or other appropriate etching technique in order to create 14 micron or smaller circular (or square) periodic structures that are patterned into polarization thin films that are deposited on an imaging sensor that includes a processor that computes from the polarization-filtered inputs the first three Stokes parameters in real-time.

A receiver is operable to detect and recover data from at least one set of received signal samples. The signal samples comprise a plurality of data bearing signal samples and a plurality of guard signal samples before or after the data bearing signal sample, the guard signal samples being formed by repeating a plurality of the data bearing signal samples. The receiver comprises a matched filter having a matched impulse response, a controller operable to adapt the impulse response of the matched filter to the signal samples of the guard signal samples, the matched filter being operable to produce an output signal which is representative of the convolution of the guard signal samples of the set with the received signal samples. A synchronization detector is operable to estimate the location of a sync position, from a distribution of energy of the matched filter output signal with respect to the received samples, the sync position providing the position of a window of the received signal samples from which the data may be recovered from the data bearing signal samples. The receiver can provide an improvement in the detection of the data bearing signal samples within the set of signal samples, by providing a more reliable estimate of the synchronization position. The receiver can be used for recovering data from signals modulated in accordance with Orthogonal Frequency Division Multiplexing (OFDM) and finds application as a receiver for Digital Video Broadcast (DVB) signals.

A radiation detection system includes many receivers to continuously receive radiation emission data from at least some of a sufficient density of dispersed detectors capable of communicating geo-positions and photon emission counts over a network; the data includes gamma intensities, time stamps, and geo-positions. A processor builds digital image data of the received radiation data for a geographic area by treating gamma-ray proton data from each dispersed detector as a pixel in a low-light image. The processor continuously executes a plurality of statistical computational analyses on the digital image data to separate detected radiation signals from random, undesired signal noise, and known signal noise or sources. The statistical computational analyses include match-filter and / or other convolution techniques. An interface reports to a user when the computational analyses result in detection of a radiation signal and reports a location of one or more of the dispersed detectors that contribute to the detection.