3029 results about "Signal characteristic" patented technology

A system and method for monitoring left ventricular cardiac contractility and for optimizing a cardiac therapy based on left ventricular lateral wall acceleration (LVA) are provided. The system includes an implantable or external cardiac stimulation device in association with a set of leads including a left ventricular epicardial or coronary sinus lead equipped with an acceleration sensor. The device receives and processes acceleration sensor signals to determine a signal characteristic indicative of LVA during isovolumic contraction. A therapy optimization method evaluates the LVA during varying therapy settings and selects the setting(s) that correspond to a maximum LVA during isovolumic contraction. In one embodiment, the optimal inter-ventricular pacing interval for use in cardiac resynchronization therapy is determined as the interval corresponding to the highest amplitude of the first LVA peak during isovolumic contraction.

The present invention is directed toward a pulse oximetry system for the determination of a physiological parameter capable of removing motion artifacts from physiological signals comprises a hardware subsystem and a software subsystem. The software subsystem is used in conjunction with the hardware subsystem to perform a method for removing a plurality of motion artifacts from the photo-plethysmographic data and for obtaining a measure of at least one physiological parameter from the data. The method comprises acquiring the raw photo-plethysmographic data, transforming the data into the frequency domain, analyzing the transformed data to locate a series of candidate cardiac spectral peaks (primary plus harmonics), reconstructing a photo-plethysmographic signal in the time domain with only the candidate cardiac spectral peaks (primary plus harmonics), computing the second order derivative of the reconstructed photo-plethysmographic signal, analyzing the candidate second order derivative photo-plethysmographic signal to determine the absence or presence of cardiac physiologic signal characteristics, and finally selecting the best physiologic candidate from the series of potential cardiac spectral peaks (primary plus harmonics) based upon a second derivative scoring system. This scoring system is preferentially based upon second derivative processing analysis, but can be equally applied using the first, third, fourth or other similar derivative processing analysis.

Some embodiments use scanning devices to characterize radio signals received at a number of locations within a geographical area of interest. The signal characteristics along with the location information associated with the characteristics are stored in a centralized reference database. A mobile device characterizes signals it receives at a certain location and compares the characteristics with the signal characteristics stored in the reference database to obtain accurate location information of the certain location.

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for detecting grid events. In one aspect, a method includes receiving signal characteristic data that specify signal characteristic values for signals that are received over each of a plurality of communications channels of a power line communications network. A determination is made that the signal characteristic values for the signals that are received over at least one of the communications channels are outside of a baseline signal value range. An endpoint that communicates over the at least one communications channel is identified, and a determination is made that a set of the signal characteristic values for the identified endpoint matches one of a plurality a grid event signatures for the identified endpoint. Data that identify the endpoint and a particular grid event that is represented by the matched grid event signature are provided.

An implantable cardiac rhythm management device operable in an autothreshold or autocapture verification mode, wherein the rhythm management device is capable of detecting noise that affects signal characteristics of a sensed intracardial evoked response electrogram signal. The device includes a noise detection circuit that determines whether a minimum peak timing occurs during a predetermined time following delivery of a stimulation pulse. If a minimum peak timing occurs during the predetermined time following delivery of the stimulation pulse, then significant amounts of noise affecting the signal characteristics of the electrocardiogram signal is assumed.

A system and method for electromagnetic position determination utilizing a calibration process. For calibration, a transmitter is positioned at multiple locations in an area of interest and multiple receivers receive and record signal characteristics from the transmitter to generate a calibration data set. The unknown position of a transmitter may be determined by receiving signals from the transmitter by multiple receivers. A locator data set is generated based on the comparison between two received signal characteristics determined for each receiver. The locator data set is compared with the calibration data set to determine the unknown position. In one embodiment, the signal comparisons are the differences between electric and magnetic field phase. Further embodiments utilize signal amplitude differences. A reciprocal method utilizing a single receiver and multiple transmitter locations is disclosed. A further method is disclosed for determining position by utilizing signals available from existing installed wiring such as power wiring.

A method, mobile station, and software product are used to select an access point in a wireless local area network (WLAN) for access by the mobile station. This is accomplished by calculating a preference value for each of a plurality of the access points, based upon information regarding current communication characteristics of the access points. That information includes physical signal characteristics of the access points, and current channel loads of the access points, and also the traffic type affecting the current channel loads of the respective access points. The information about channel loads is weighted differently based upon the corresponding traffic types, and may also be calculated differently depending upon whether or not the mobile station is set up to utilize multimedia traffic.

A method and system for enhancing the accuracy and robustness of locations determined for a mobile wireless transceiver in a cellular telephone communications system integrates location-related information both from an assisted GPS device embedded in the mobile unit and from infrastructure-based facilities that extract signal characteristic data at networked base stations. Available supporting collateral information may be additionally evaluated in the location determinations to provide location estimates of enhanced robustness and accuracy.

A system and method for monitoring left ventricular (LV) lateral wall motion and for optimizing cardiac pacing intervals based on left ventricular lateral wall motion is provided. The system includes an implantable or external cardiac stimulation device in association with a set of leads including a left ventricular epicardial or coronary sinus lead equipped with a motion sensor electromechanically coupled to the lateral wall of the left ventricle. The device receives and processes wall motion sensor signals to determine a signal characteristic indicative of systolic LV lateral wall motion or acceleration. An automatic pacing interval optimization method evaluates the LV lateral wall motion during varying pacing interval settings, including atrial-ventricular intervals and inter-ventricular intervals and selects the pacing interval setting(s) that correspond to LV lateral wall motion associated with improved cardiac synchrony and hemodynamic performance.

A guide wire for measuring physiological characteristics inside a body includes a sensor (14) for monitoring the physical variable and for forming an output signal characteristic for the value of the physical variable. The sensor is connected to a first electrical potential of an electronic unit (22) via an electrical wire (11) extending along the guide wire. An internal body electrode (17) is connected to the sensor (14) and is in contact with body fluids surrounding the sensor circuit. The guide wire (10) is inserted into a vessel of the body (25), and a second electrode (21) is applied near the internal body electrode, and the sensor circuit is powered by a second potential of the electronic unit (22) via a part of the body.

A physiologic data acquisition system includes an analog input, a sigma-delta front end signal conditioning circuit adapted to subtract out DC and low frequency interfering signals from and amplify the analog input before analog to digital conversion. The system can be programmed to acquire a selected physiologic signal, e.g., a physiologic signal characteristic of or originating from a particular biological tissue. The physiologic data acquisition system may include a network interface modulating a plurality of subcarriers with respective portions of an acquired physiologic signal. A receiver coupled to the network interface can receive physiologic data from, and send control signals and provide power to the physiologic data acquisition system over a single pair of wires. The network interface can modulate an RF carrier with the plurality of modulated subcarriers and transmit the resulting signal to the receiver across a wireless network. An integrated circuit may include the physiologic data acquisition system. Also included are methods for acquiring physiologic data comprising the step of selectively controlling an acquisition circuit to acquire the physiologic signal.

An apparatus for monitoring speaker cone displacement in an audio speaker includes: (a) an electromagnetic coil structure; (b) a ferrous core structure; the ferrous core structure and the electromagnetic coil structure being mounted with the speaker to effect variable electromagnetic coupling between the ferrous core structure and the electromagnetic coil structure as the speaker cone moves; (c) a signal injecting circuit coupled with the electromagnetic coil structure for injecting a predetermined input signal into the electromagnetic coil structure; and (d) a signal monitoring circuit coupled with the electromagnetic coil structure; the signal monitoring circuit receiving an output signal from the electromagnetic coil structure and generating an indicating signal based upon the output signal; at least one signal characteristic of the indicating signal being related with the cone displacement.

Methods, apparatus and systems for dynamically controlling a digital communication system, such as a DSL system, collect information about digital communication lines in the system and adaptively and / or dynamically determine line and signal characteristics of the digital communication lines, including interference effects. Based on the determined characteristics and the desired performance parameters, operation of the digital communication lines is adjusted to improve or otherwise control the performance of the system. The collection and processing of information may be performed by a party that is not a user in the system. This independent party also may control operational characteristics and parameters of the system. The invention can be used to eliminate or reduce signal interference such as crosstalk that can be induced on communication lines in systems such as DSL systems. Specific iterative power allocation and vectored transmission techniques and apparatus are disclosed.

Systems and methods of identifying molecules of polymers such as, for example, a nucleic acid, are described. The method involves centering a bias voltage across a pair of nanoelectrodes separated by a channel that corresponds to one of any of the energy differences between any two internal energy levels of a molecule of interest, and modulating the bias voltage with a modulation waveform while the molecule of interest is in the channel. An electrical signal characteristic of the molecule of interest is derived from the tunneling current between the nanoelectrodes, and the characteristic electrical signal is compared with known values of the signal for chemically-known molecules in order to identify the molecule of interest. Multiple pairs of nano-electrodes may be employed to identify more reliably a single molecule or multiple molecules.

A communication device for transmitting and / or receiving signals by using a communication antenna includes signal characteristic information detection means for detecting information regarding signal characteristics of a calibration signal which are contained in a signal received by the communication antenna, calibration means for calibrating a communication antenna chain based on the detected signal characteristic information, and cancellation signal generating means for generating a cancellation signal corresponding to a calibration signal contained in the signal received by the communication antenna based on the calibration signal. The device also includes signal cancellation-by-subtraction means for subtracting the generated cancellation signal from the signal received by the communication antenna, and receive signal processing means for processing the received signal that is diminished by the cancellation signal.

The present invention is directed toward a pulse oximetry system for the determination of a physiological parameter capable of removing motion artifacts from physiological signals comprises a hardware subsystem and a software subsystem. The software subsystem is used in conjunction with the hardware subsystem to perform a method for removing a plurality of motion artifacts from the photo-plethysmographic data and for obtaining a measure of at least one physiological parameter from the data. The method comprises acquiring the raw photo-plethysmographic data, transforming the data into the frequency domain, analyzing the transformed data to locate a series of candidate cardiac spectral peaks (primary plus harmonics), reconstructing a photo-plethysmographic signal in the time domain with only the candidate cardiac spectral peaks (primary plus harmonics), computing the second order derivative of the reconstructed photo-plethysmographic signal, analyzing the candidate second order derivative photo-plethysmographic signal to determine the absence or presence of cardiac physiologic signal characteristics, and finally selecting the best physiologic candidate from the series of potential cardiac spectral peaks (primary plus harmonics) based upon a second derivative scoring system. This scoring system is preferentially based upon second derivative processing analysis, but can be equally applied using the first, third, fourth or other similar derivative processing analysis.

The invention provides a voiceprint identification method based on a Gauss mixing model and a system thereof. The method comprises the following steps: voice signal acquisition; voice signal pretreatment; voice signal characteristic parameter extraction: employing a Mel Frequency Cepstrum Coefficient (MFCC), wherein an order number of the MFCC usually is 12-16; model training: employing an EM algorithm to train a Gauss mixing model (GMM) for a voice signal characteristic parameter of a speaker, wherein a k-means algorithm is selected as a parameter initialization method of the model; voiceprint identification: comparing a collected voice signal characteristic parameter to be identified with an established speaker voice model, carrying out determination according to a maximum posterior probability method, and if a corresponding speaker model enables a speaker voice characteristic vector X to be identified to has maximum posterior probability, identifying the speaker. According to the method, the Gauss mixing model based on probability statistics is employed, characteristic distribution of the speaker in characteristic space can be reflected well, a probability density function is common, a parameter in the model is easy to estimate and train, and the method has good identification performance and anti-noise capability.

The present invention relates to a method for generating and apparatus for employing code families having desirable correlation properties. Regardless of code length, maximum autocorrelation of the codes is 4 for any nonzero offset and maximum cross-correlation of any two codes from a code family is 4 for any offset. The codes can be used in impulse radio systems and non-impulse radio systems including CDMA, TDMA, FDMA, OFDM and various other frequency hopping and direct sequence systems. The codes can be used to specify various impulse radio and non-impulse radio signal characteristics including pulse position in time, amplitude, width, type, phase, phase difference, frequency, spreading code, etc. The codes have the unique property that they can specify as many as two components in which a signal is not present. A method of code compression is provided.

An analysis device for in vivo determination of an analyte in a patient's body, comprising a transdermal measurement probe (2) adapted to be introduced through the skin surface (4) into the body, with a probe head (6) including an electro-chemical analysis sensor (7) with two measurement electrodes (25, 26, 27), a body-wearable probe connection unit (3) adapted to be worn on the body and for connection to the transdermal measurement probe (2), a test circuit (22) connected with the measurement electrodes (25, 26, 27), wherein after contact of the measurement electrodes (25, 26, 27) with a body fluid the test circuit (22) generates a test signal characteristic for the desired analysis result, an evaluation circuit (23) for evaluating test signals from the test circuit (22) and for generating an information about the desired analysis result, wherein the test circuit (22) is integrated in the probe head (6) as part of probe head electronics (10), the probe head (6) is coupled to light conductor (8, 18), the probe head (6) includes an optical sensor (17) for converting electrical signals from the probe head electronics (10) into light signals, and for transmitting the light signals via the light conductor (8, 18) coupled to the probe head (6), and the probe connection unit (3) contains a light receiver (28) for receiving the light signals from the measurement probe (2) for further processing.

A transmit-rake apparatus includes at least one pulse generator that provides a plurality of pulses with selected signal properties so as to improve the signal-to-noise ratio at a receiver. The signal properties may include pulse timing, amplitude, polarity, and pulse shape. The transmit-rake apparatus may use a multipath analyzer, receive multipath or signal-quality information, or use a combination of those techniques. The multipath analyzer may include a scanning receiver to generate a scan of the multipath response. Correlation of the multipath response with a model pulse shape may be used to establish pulse position and amplitude. Iteration based on link performance measurements may be used to select or refine pulse properties. A method is disclosed to vary the selection of pulses to improve the spectrum.

A method of performing a cell reselection procedure in a wireless communication system includes evaluating priorities of a serving cell and neighbor cells, each of which use different frequency bands, performing inter-frequency measurement on a neighbor cell which has a higher priority than the serving cell, performing the inter-frequency measurement on a neighbor cell which has an equal or lower priority than the serving cell, when a signal characteristic of the serving cell is less than a threshold, and performing cell reselection according to the priorities.

A mixing method and mixer structure provide a circuit topology suitable for use in radio receivers, transmitters, tuners, instrumentation systems, telemetry systems, and other systems and devices performing frequency conversion in either homodyne or heterodyne implementations. The inventive mixer may be used for wireless communication devices including radios, cellular telephones, and telemetry systems whether land, sea, airborne, or space based, and whether fixed or mobile. The mixer provides superior intermodulation and harmonic distortion suppression and features excellent conversion loss, noise figure, port match, and port isolation as a result of its circuit topology. The mixer device circuit combines the advantages of series mixing FETs, a triple balanced design using a balanced passive reflection transformer, a precise local oscillator phase splitter, and square wave gate drive having high slew rate signal characteristics to achieve high levels of performance. It is power conservative and offers the advantage of long battery life in portable devices such as portable radios and cellular telephones as it requires only a modest amount of DC and local oscillator drive power, and is useful for operation over at least a multi-decade bandwidth.

A touch pad (101) includes transducers (201-204) for receiving acoustic signals resulting from touch events, such as the continuous movement of a fingertip across the surface (105) of the touch pad. The acoustic signals are acquired at different transducer locations in the surface. Signals from different transducers ate combined, preferably in antiphase, to improve signal characteristics. The transducer signals are supplied to a stereo analogue to digital converter (407). Phase differences (706) are obtained and compared (703) with phase difference profiles (607) of known location, in order to identify the location of the touch event. An index (606) is used to identify candidate locations to reduce the amount of processing. Interpolation (705) is used to locate the touch event between profile locations.

A headphone device includes: a sound reproduction unit having a diaphragm which is configured to perform sound reproduction based on a sound signal; a sound pickup unit configured to perform a sound pickup operation; a filtering unit configured to apply filtering to a picked-up sound signal obtained by the sound pickup unit, to give a noise-cancelling signal characteristic; a combining unit configured to combine the picked-up sound signal that has undergone filtering, and a listening sound signal which is inputted separately, to generate a sound signal supplied to the sound reproduction unit; and an abnormality determination unit configured to determine occurrence or non-occurrence of an abnormal sound, on the basis of a result of level detection of a sound signal obtained within a sound signal processing system that includes the filtering unit and the combining unit and is formed between the sound pickup unit and the sound reproduction unit.

An envelope tracking radio frequency (RF) power amplifier having an adaptive envelope signal processing circuit is disclosed. An RF input voltage is sampled by the adaptive envelope signal processing circuit which provides control signals to the power supply which supplies voltages to RF power devices in order to simultaneously satisfy two operating conditions: a) provide best possible efficiency of the power amplifier stages depending on the input signal characteristics and b) provide compensation for RF transistor AM-AM and AM-PM distortion compensation across the power range. In particular, the voltage control provides for constant power amplifier gain across the input signal dynamic range, thus minimizing power amplifier amplitude distortions and extending the useful power amplifier linear dynamic range up to saturation point. The power amplifier thus exhibits better linearity and efficiency than offered by conventional techniques and topologies.

A method and system is described for more optimally managing the usage of a wideband space-time multipath channel. The wideband space-time multipath channel is decomposed into a plurality of orthogonal sub-channels, where the orthogonal sub-channels having the best signaling characteristics are used for transmitting one or more signal streams. For purposes of decomposing the wideband space-time multipath channel into a plurality of orthogonal sub-channels, channel estimates are determined for each signal propagation path. A closed-form singular value decomposition of the channel corresponding to each receive antenna before coherent combining is utilized to obtain an orthogonal decomposition of the overall effective space-time channel after coherent combining. By using the overall effective space-time channel after coherent combining rather than before coherent combining, the complexity and correspondingly the resources required for obtaining the orthogonal sub-channels is significantly reduced. The method and system further provide for transmit power to be allocated between the selected sub-channels in order to minimize the effective bit-error rate for a fixed average throughput or to maximize average throughput for a fixed minimum effective bit-error rate.

The present invention is a system and method for coverage analysis in a wireless network. The invention seeks to evaluate the location and characteristics of a proposed base station in a wireless communication network, prior to the base station being erected. Data is collected from both: a test transmitter of known characteristics, erected at the proposed location for the proposed base station; and from a plurality of wireless channels of the existing network. The data may be collected at a plurality of measurement locations. The collected data is used to model and subsequently evaluate the behaviour of the network in the presence of channels that would be introduced into the network if the new base station were erected. Modeled data may include estimates of signal to noise ratios for various wireless channels for both existing base stations and the proposed base station, at the measurement location. The model data may be displayed on a GUI, depicting modeled signal characteristics in a geographical area surrounding the proposed base station, to estimate overall acceptability of a proposed base station at a proposed location before incurring the cost of installing the base station.

A vibrotactile transducer provides a point-like vibrational stimulus to the body of a user in response to an electrical input. The apparatus includes a housing held in contact with the skin and a moving mechanical contactor protruding through in an opening in said housing and preloaded into skin. The contactor is attached to a torroidal moving magnet assembly suspended by springs in a magnetic circuit assembly consisting of a housing containing a pair of electrical coils. The mass of the magnet / contactor assembly and the compliance of the spring are chosen so that the electromechanical resonance of the motional masses, when loaded by a typical skin site on the human body, are in a frequency band where the human body is most sensitive to vibrational stimuli. By varying the drive signal to the vibrotactile transducer and activating one or more transducer at specific location on the body using an appropriate choice of signal characteristics and / or modulation, different information can be provided to a user in a intuitive, body referenced manner.