Showing papers on "Signal published in 2007"

Signal Recovery from Random Measurements Via Orthogonal Matching Pursuit: The Gaussian Case

Abstract: This report demonstrates theoretically and empirically that a greedy algorithm called Orthogonal Matching Pursuit (OMP) can reliably recover a signal with m nonzero entries in dimension d given O(mln d) random linear measurements of that signal. This is a massive improvement over previous results, which require O(m2) measurements. The new results for OMP are comparable with recent results for another approach called Basis Pursuit (BP). In some settings, the OMP algorithm is faster and easier to implement, so it is an attractive alternative to BP for signal recovery problems.

Compressive Radar Imaging

Abstract: We introduce a new approach to radar imaging based on the concept of compressive sensing (CS). In CS, a low-dimensional, nonadaptive, linear projection is used to acquire an efficient representation of a compressible signal directly using just a few measurements. The signal is then reconstructed by solving an inverse problem either through a linear program or a greedy pursuit. We demonstrate that CS has the potential to make two significant improvements to radar systems: (i) eliminating the need for the pulse compression matched filter at the receiver, and (ii) reducing the required receiver analog-to-digital conversion bandwidth so that it need operate only at the radar reflectivity's potentially low "information rate" rather than at its potentially high Nyquist rate. These ideas could enable the design of new, simplified radar systems, shifting the emphasis from expensive receiver hardware to smart signal recovery algorithms.

Electrical detection of spin transport in lateral ferromagnet–semiconductor devices

Abstract: The development of semiconductor spintronics requires a reliable electronic means for writing, processing and reading information using spin-polarized carriers. Here, we demonstrate a fully electrical scheme for achieving spin injection, transport and detection in a single device. Our device consists of a lateral semiconducting channel with two ferromagnetic contacts, one of which serves as a source of spin-polarized electrons and the other as a detector. Spin detection in the device is achieved through a non-local, spin-sensitive, Schottky-tunnel-barrier contact whose electrochemical potential depends on the relative magnetizations of the source and detector. We verify the effectiveness of this approach by showing that a transverse magnetic field suppresses the non-local signal at the detection contact by inducing spin precession and dephasing in the channel (the Hanle effect). The sign of the signal varies with the injection current and is correlated with the spin polarization in the channel as determined by optical Kerr rotation measurements.

Blind Multi-Band Signal Reconstruction: Compressed Sensing for Analog Signals

Abstract: We address the problem of reconstructing a multi-band signal from its sub-Nyquist point-wise samples. To date, all reconstruction methods proposed for this class of signals assumed knowledge of the band locations. In this paper, we develop a non-linear blind perfect reconstruction scheme for multi-band signals which does not require the band locations. Our approach assumes an existing blind multi-coset sampling method. The sparse structure of multi-band signals in the continuous frequency domain is used to replace the continuous reconstruction with a single finite dimensional problem without the need for discretization. The resulting problem can be formulated within the framework of compressed sensing, and thus can be solved efficiently using known tractable algorithms from this emerging area. We also develop a theoretical lower bound on the average sampling rate required for blind signal reconstruction, which is twice the minimal rate of known-spectrum recovery. Our method ensures perfect reconstruction for a wide class of signals sampled at the minimal rate. Numerical experiments are presented demonstrating blind sampling and reconstruction with minimal sampling rate.

System and method for closed loop monitoring of monopolar electrosurgical apparatus

Abstract: An electrosurgical system is disclosed comprising a generator configured to electrosurgical coagulation waveforms. The generator includes a closed loop control system for controlling the electrosurgical coagulation waveforms. The closed loop control system includes a sensor configured to sense a tissue property and/or an energy property and to transmit the tissue property and/or the energy property as one or more sensor signals having an amplitude. The control system also includes a gain controller configured to process the at least one sensor signal to reduce the amplitude of the sensor signals and to obtain a signal to noise ratio of the at sensor signals within a predetermine range. A microprocessor coupled to the generator and is configured to adjust the electrosurgical coagulation waveforms as a function of the sensor signals.

Battery management system and driving method thereof

Abstract: A battery management system (BMS) includes at least one sub-BMS and a main BMS. The at least one sub-BMS measures information about a battery, and generates an activation signal according to operating state. The main BMS receives the activation signal and determines the operating state of the at least two sub-BMSs. If the at least two sub-BMSs normally operate, the main BMS generates a synchronization signal and transfers the same to the sub-BMSs. The at least one sub-BMS measures the information about the battery according to the synchronization signal.

Initiating medical system communications

Abstract: A medical system includes a body-contacting signal source adapted to transmit an oscillatory signal though a body to a transducer of a device implanted therein. A detector that is coupled to the transducer, upon detection of a response of the transducer to the signal, activates a radio-frequency (RF) telemetry component of the device.

Systems and methods for replacing signal data artifacts in a glucose sensor data stream

Abstract: Systems and methods for detecting noise episodes and processing analyte sensor data responsive thereto. In some embodiments, processing analyte sensor data includes filtering the sensor data to reduce or eliminate the effects of the noise episode on the signal.

EMD-Based Signal Filtering

Abstract: In this paper, a signal-filtering method based on empirical mode decomposition is proposed. The filtering method is a fully data-driven approach. A noisy signal is adaptively decomposed into intrinsic oscillatory components called intrinsic mode functions (IMFs) by means of an algorithm referred to as a sifting process. The basic principle of the method is to make use of partial reconstructions of the signal, with the relevant IMFs corresponding to the most important structures of the signal (low-frequency components). A criterion is proposed to determine the IMF, after which, the energy distribution of the important structures of the signal overcomes that of the noise and that of the high-frequency components of the signal. The method is illustrated on simulated and real data, and the results are compared to well-known filtering methods. The study is limited to signals that were corrupted by additive white Gaussian noise and is conducted on the basis of extended numerical experiments.

Apparatus and method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands

Abstract: Apparatus and method for increasing the sensitivity in the detection of optical coherence tomography and low coherence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source is split into N spectral bands. The N spectral bands are individually detected and processed to provide an increase in the signal-to-noise ratio by a factor of N. Each spectral band is detected by a separate photo detector and amplified. For each spectral band the signal is band pass filtered around the signal band by analog electronics and digitized, or, alternatively, the signal may be digitized and band pass filtered in software. As a consequence, the shot noise contribution to the signal is reduced by a factor equal to the number of spectral bands. The signal remains the same. The reduction of the shot noise increases the dynamic range and sensitivity of the system.

Method and apparatus for delivering energy to an electrical or electronic device via a wireless link

Abstract: A method and apparatus for providing power to e.g., a chargeable device via a radio frequency link. In one aspect, a method of providing power to a chargeable device via radio frequency link comprises generating a substantially un-modulated signal. The method further comprises radiating a substantially un-modulated radio frequency (RF) signal to the chargeable device via a transmit antenna based on the substantially un-modulated signal. The method further comprises powering or charging the chargeable device with power delivered by the substantially un-modulated RF signal.

Method and system for powering an electronic device via a wireless link

Abstract: A method and system for providing power to a chargeable device via radio frequency link are provided. In one aspect, a method of providing power to a chargeable device via radio frequency link comprises generating a substantially unmodulated signal. The method further comprises radiating a substantially unmodulated radio frequency (RP) signal to the chargeable device via a transmit antenna based on the substantially unmodulated signal. The method further comprises powering or charging the chargeable device with power delivered by the substantially unmodulated RF signal.

Dual electrode system for a continuous analyte sensor

Abstract: Disclosed herein are systems and methods for a continuous analyte sensor, such as a continuous glucose sensor. One such system utilizes first and second working electrodes to measure additional analyte or non-analyte related signal. Such measurements may provide a background and/or sensitivity measurement(s) for use in processing sensor data and may be used to trigger events such as digital filtering of data or suspending display of data.

Contact-Free Measurement of Cardiac Pulse Based on the Analysis of Thermal Imagery

Abstract: We have developed a novel method to measure human cardiac pulse at a distance. It is based on the information contained in the thermal signal emitted from major superficial vessels. This signal is acquired through a highly sensitive thermal imaging system. Temperature on the vessel is modulated by pulsative blood flow. To compute the frequency of modulation (pulse), we extract a line-based region along the vessel. Then, we apply fast Fourier transform (FFT) to individual points along this line of interest to capitalize on the pulse's thermal propagation effect. Finally, we use an adaptive estimation function on the average FFT outcome to quantify the pulse. We have carried out experiments on a data set of 34 subjects and compared the pulse computed from our thermal signal analysis method to concomitant ground-truth measurements obtained through a standard contact sensor (piezo-electric transducer). The performance of the new method ranges from 88.52% to 90.33% depending on the clarity of the vessel's thermal imprint. To the best of our knowledge, it is the first time that cardiac pulse has been measured several feet away from a subject with passive means.

Front-end signal compensation

Abstract: A touch surface device having improved sensitivity and dynamic range is disclosed. In one embodiment, the touch surface device includes a touch-sensitive panel having at least one sense node for providing an output signal indicative of a touch or no-touch condition on the panel; a compensation circuit, coupled to the at least one sense node, for generating a compensation signal that when summed with the output signal removes an undesired portion of the output signal so as to generated a compensated output signal; and an amplifier having an inverting input coupled to the output of the compensation circuit and a non-inverting input coupled to a known reference voltage.

Method and apparatus for estimating a motion parameter

Abstract: A system for estimating motion parameters corresponding to a user. The system may generally include a receiver operable to receive a signal from an external source, an inertial sensor operable to be coupled with the user and arbitrarily oriented relative to the direction of user motion for generation of a signal corresponding to user motion, and a processing system in communication with the receiver and inertial sensor. The processing system can be operable to utilize the receiver signal to estimate a first parameter corresponding to a first motion parameter type, utilize the inertial sensor signal to estimate a second parameter corresponding to a second motion parameter type, generate a user-specific motion model to correlate the first parameter type and second parameter type using at least the first and second estimated parameters, utilize the inertial sensor signal to estimate a third parameter corresponding to the second parameter type, and utilize the motion model and the third parameter to estimate a fourth parameter corresponding to the first parameter type independent of the receiver signal.

Maximum-Minimum Eigenvalue Detection for Cognitive Radio

Abstract: Sensing (signal detection) is a fundamental problem in cognitive radio. In this paper, a new method is proposed based on the eigenvalues of the covariance matrix of the received signal. It is shown that the ratio of the maximum eigenvalue to the minimum eigenvalue can be used to detect the signal existence. Based on some latest random matrix theories (RMT), we can quantize the ratio and find the threshold. The probability of false alarm is also found by using the RMT. The proposed method overcomes the noise uncertainty difficulty while keeps the advantages of the energy detection. The method can be used for various sensing applications without knowledge of the signal, the channel and noise power. Simulations based on randomly generated signals and captured ATSC DTV signals are presented to verify the methods.

Motor drive circuit with short startup time

Abstract: An H-bridge circuit is connected to a coil of the vibration motor that is to be driven. A comparator receives Hall signals indicating position information of a rotor of the vibration motor, and converts to an FG signal. A pulse width modulator generates a pulse-modulated pulse signal specifying energization time of the coil of the vibration motor. The pulse width modulator, in a first mode, after commencing start-up of the vibration motor, sets a duty ratio of the pulse signal to 100%, and after that, switches the duty ratio to a predetermined value in accordance with rotational frequency of the motor. In a second mode, the duty ratio of the pulse signal continues to be set to 100%. In a third mode, frequency and the duty ratio of the pulse signal are set based on a control signal of a pulse form inputted from outside. The control signal is used also in switching mode.

Supervising and sequencing commonly driven power supplies with digital information

Abstract: Methods and apparatus for power monitoring with sequencing and supervision are disclosed. An example method disclosed herein includes supervising a first power rail and a second power rail, sequencing a first enable signal associated with the first power rail and a second enable signal associated with the second power rail, and determining whether the first power rail is enabled based on regulation information determined while supervising the first power rail.

One sketch for all: fast algorithms for compressed sensing

Abstract: Compressed Sensing is a new paradigm for acquiring the compressible signals that arise in many applications. These signals can be approximated using an amount of information much smaller than the nominal dimension of the signal. Traditional approaches acquire the entire signal and process it to extract the information. The new approach acquires a small number of nonadaptive linear measurements of the signal and uses sophisticated algorithms to determine its information content. Emerging technologies can compute these general linear measurements of a signal at unit cost per measurement.This paper exhibits a randomized measurement ensemble and a signal reconstruction algorithm that satisfy four requirements: 1. The measurement ensemble succeeds for all signals, with high probability over the random choices in its construction. 2. The number of measurements of the signal is optimal, except for a factor polylogarithmic in the signal length. 3. The running time of the algorithm is polynomial in the amount of information in the signal and polylogarithmic in the signal length. 4. The recovery algorithm offers the strongest possible type of error guarantee. Moreover, it is a fully polynomial approximation scheme with respect to this type of error bound.Emerging applications demand this level of performance. Yet no otheralgorithm in the literature simultaneously achieves all four of these desiderata.

Proximity and multi-touch sensor detection and demodulation

Abstract: The use of one or more proximity sensors in combination with one or more touch sensors in a multi-touch panel to detect the presence of a finger, body part or other object and control or trigger one or more functions in accordance with an “image” of touch provided by the sensor outputs is disclosed. In some embodiments, one or more infrared (IR) proximity sensors can be driven with a specific stimulation frequency and emit IR light from one or more areas, which can in some embodiments correspond to one or more multi-touch sensor “pixel” locations. The reflected IR signal, if any, can be demodulated using synchronous demodulation. In some embodiments, both physical interfaces (touch and proximity sensors) can be connected to analog channels in the same electrical core.

Intrinsic time-scale decomposition: time-frequency-energy analysis and real-time filtering of non-stationary signals

Abstract: We introduce a new algorithm, the intrinsic time-scale decomposition (ITD), for efficient and precise time–frequency–energy (TFE) analysis of signals. The ITD method overcomes many of the limitations of both classical (e.g. Fourier transform or wavelet transform based) and more recent (empirical mode decomposition based) approaches to TFE analysis of signals that are nonlinear and/or non-stationary in nature. The ITD method decomposes a signal into (i) a sum of proper rotation components, for which instantaneous frequency and amplitude are well defined, and (ii) a monotonic trend. The decomposition preserves precise temporal information regarding signal critical points and riding waves, with a temporal resolution equal to the time-scale of extrema occurrence in the input signal. We also demonstrate how the ITD enables application of single-wave analysis and how this, in turn, leads to a powerful new class of real-time signal filters, which extract and utilize the inherent instantaneous amplitude and frequency/phase information in combination with other relevant morphological features.

Dynamic Modeling and Analysis of $Z$ Source Converter—Derivation of AC Small Signal Model and Design-Oriented Analysis

Abstract: This paper contributes to the AC small signal modeling and analysis of Z source converter (ZSC) in continuous conduction mode. The AC small signal model considers the dynamics introduced by Z network uniquely contained in ZSC. AC small signal model of ZSC is derived and computer simulation results are used to validate the small signal modeling method. Various applications of the AC small signal models to ZSC design and experimental verifications are presented.

Camera using multiple lenses and image sensors to provide improved focusing capability

Abstract: An electronic camera for producing an output image of a scene from a captured image signal includes: (a) a first imaging stage comprising a first image sensor for generating a first sensor output; a first lens for forming a first image of the scene on the first image sensor; and a first lens focus adjuster for adjusting focus of the first lens responsive to a first focus detection signal; and (b) a second imaging stage comprising a second image sensor for generating a second sensor output; a second lens for forming a second image of the scene on the second image sensor; and a second lens focus adjuster for adjusting focus of the second lens responsive to a second focus detection signal. A processing stage either (a) selects the sensor output from the first imaging stage as the captured image signal and uses the sensor output from the second imaging stage to generate the first focus detection signal for the selected imaging stage, or (b) selects the sensor output from the second imaging stage as the captured image signal and uses the sensor output from the first imaging stage to generate the second focus detection signal for the selected imaging stage.

Covariance Based Signal Detections for Cognitive Radio

Abstract: Sensing (signal detection) is a fundamental problem in cognitive radio. The statistical covariances of signal and noise are usually different. In this paper, this property is used to differentiate signal from noise. The sample covariance matrix of the received signal is computed and transformed based on the receiving filter. Then two detection methods are proposed based on the transformed sample covariance matrix. One is the covariance absolute value (CAV) detection and the other is the covariance Frobenius norm (CFN) detection. Theoretical analysis and threshold setting for the algorithms are discussed. Both methods do not need any information of the signal, the channel and noise power as a priori. Simulations based on captured ATSC DTV signals are presented to verify the methods.

Optimal Signal Design for Detection of Gaussian Point Targets in Stationary Gaussian Clutter/Reverberation

Abstract: In this paper, we address the design of an optimal transmit signal and its corresponding optimal detector for a radar or active sonar system. The focus is on the temporal aspects of the waveform with the spatial aspects to be described in a future paper. The assumptions involved in modeling the clutter/reverberation return are crucial to the development of the optimal detector and its consequent optimal signal design. In particular, the target is assumed to be a Gaussian point target and the clutter/reverberation a stationary Gaussian random process. In practice, therefore, the modeling will need to be assessed and possibly extended, and additionally a means of measuring the "in-situ" clutter/reverberation spectrum will be required. The advantages of our approach are that a simple analytical result is obtained which is guaranteed to be optimal, and also the extension to spatial-temporal signal design is immediate using ideas of frequency-wavenumber representations. Some examples are given to illustrate the signal design procedure as well as the calculation of the increase in processing gain. Finally, the results are shown to be an extension of the usual procedure which places the signal energy in the noise band having minimum power

Radio frequency power amplifier and method using a controlled supply

Abstract: A radio frequency power amplifier includes a feedback control system coupled to an input signal and a first feedback signal and configured to provide an output; a controlled supply configured to provide power that is controlled in accordance with a signal; and a radio frequency gain stage powered from the controlled supply, driven by the output from the feedback control system, and configured to provide an output signal at the radio frequency to a resonant load, where the first feedback signal corresponds to the output signal. Some embodiments include a sequencer in the feedback control system and others utilize an additional feedback loop to control the power provided by the controlled supply.

Semiconductor device and power receiving device

Abstract: An object is to provide a semiconductor device that is capable of wireless communication, such as an RFID tag, which can transmit and receive individual information without checking remaining capacity of a battery or changing batteries due to deterioration with time in the battery for a drive power supply voltage, and maintain a favorable a transmission/reception state even when electric power of an electromagnetic wave from a reader/writer is not sufficient. The semiconductor device includes a signal processing circuit, a first antenna circuit connected to the signal processing circuit, an antenna circuit group, a rectifier circuit group and a battery connected to the signal processing circuit. The first antenna circuit transmits and receives a signal for transmitting data stored in the signal processing circuit and drives a power supply circuit, and each antenna circuit of the antenna circuit group receives a signal for charging the battery and includes an antenna which has a different corresponding frequency.

Ultrasonic Through-Wall Communication (UTWC) System

Abstract: Apparatus for communicating information across a solid wall has one or two outside ultrasonic transducers coupled to an outside surface of the wall and connected to a carrier generator for sending an ultrasonic carrier signal into the wall and for receiving an output information signal from the wall. One or two inside ultrasonic transducers are coupled to an inside surface of the wall and one of them introduces the output information signal into the wall. When there are two inside transducers inside the wall, one receives the carrier signal and the second transmits the carrier after it is modulated by the output information from the sensor. When there is one inside transducer, the output information from the sensor is transmitted by changing the reflected or returned signal from the inside transducer. A power harvesting circuit inside the wall harvests power from the carrier signal and uses it to power the sensor.

Compensation of I-Q imbalance in digital transceivers

Abstract: A transceiver includes a switching unit configurable for isolating an input of a receiver from an output of a transmitter during a local calibration mode. A known signal present at the output at a first power level during the calibration mode will also be present at the input at a second power level lower than the first power level and will be converted by the quadrature demodulator. A compensation factor is estimated for compensating the receiver section for imbalances in the in-phase and quadrature phase signals resulting from conversion of the known signal. Remote calibration is implemented using a method for remotely compensating for I-Q imbalance wherein a data packet having a known signal is transmitted to a receiver for conversion by a quadrature demodulator and compensation factors are estimated for compensating for imbalances in the in-phase and quadrature phase signals resulting from conversion of the known signal.