Showing papers on "Signal published in 2008"

Remote plethysmographic imaging using ambient light

Abstract: Plethysmographic signals were measured remotely (>1m) using ambient light and a simple consumer level digital camera in movie mode. Heart and respiration rates could be quantified up to several harmonics. Although the green channel featuring the strongest plethysmographic signal, corresponding to an absorption peak by (oxy-) hemoglobin, the red and blue channels also contained plethysmographic information. The results show that ambient light photo-plethysmography may be useful for medical purposes such as characterization of vascular skin lesions (e.g., port wine stains) and remote sensing of vital signs (e.g., heart and respiration rates) for triage or sports purposes.

Active Elements for Analog Signal Processing: Classification, Review, and New Proposals

Abstract: In the paper, an analysis of the state-of-the-art of active elements for analog signal processing is presented which support - in contrast to the conven tional operational amplifiers - not only the voltage-mode but also the current- and mixed-mode operations. Several pro blems are addressed which are associated with the utiliza tion of these elements in linear applications, particularly in frequency filters. A methodology is proposed which generates a number of fundamentally new active elem ents with their potential utilization in various areas o f signal processing.

A Survey on Wireless Position Estimation

Abstract: In this paper, an overview of various algorithms for wireless position estimation is presented. Although the position of a node in a wireless network can be estimated directly from the signals traveling between that node and a number of reference nodes, it is more practical to estimate a set of signal parameters first, and then to obtain the final position estimation using those estimated parameters. In the first step of such a two-step positioning algorithm, various signal parameters such as time of arrival, angle of arrival or signal strength are estimated. In the second step, mapping, geometric or statistical approaches are commonly employed. In addition to various positioning algorithms, theoretical limits on their estimation accuracy are also presented in terms of Cramer---Rao lower bounds.

Spectrum Sensing Algorithms for Cognitive Radio Based on Statistical Covariances

Abstract: Spectrum sensing, i.e., detecting the presence of primary users in a licensed spectrum, is a fundamental problem in cognitive radio. Since the statistical covariances of received signal and noise are usually different, they can be used to differentiate the case where the primary user's signal is present from the case where there is only noise. In this paper, spectrum sensing algorithms are proposed based on the sample covariance matrix calculated from a limited number of received signal samples. Two test statistics are then extracted from the sample covariance matrix. A decision on the signal presence is made by comparing the two test statistics. Theoretical analysis for the proposed algorithms is given. Detection probability and associated threshold are found based on statistical theory. The methods do not need any information of the signal, the channel and noise power a priori. Also, no synchronization is needed. Simulations based on narrowband signals, captured digital television (DTV) signals and multiple antenna signals are presented to verify the methods.

Biological sensing with haptic feedback

Abstract: Systems and methods as described the present disclosure are capable of generating haptic feedback in response to sensing a biological signal from a vertebrate. A method according to one embodiment, among others, includes detecting a neural signal from a vertebrate. The method also includes generating a haptic effect on the vertebrate corresponding to the neural signal.

Piezoelectric multifrequency energy converter for power harvesting in autonomous microsystems

Abstract: A multifrequency mechanoelectrical piezoelectric converter intended for powering autonomous sensors from background vibrations is presented. The converter is composed of multiple bimorph cantilevers with different natural frequencies, whose rectified outputs are fed to a single storage capacitor. The structure of the converter, description of the operation, and measurement data on the performances are reported. Experimental results show the possibility of using the converter with input vibrations across a wideband frequency spectrum, improving the effectiveness of the overall energy conversion over the case of a single converter. The converter was used to supply power to a battery-less sensor module that intermittently reads the signal from a passive sensor and sends the measurement information via RF transmission, in this way forming an autonomous sensor system with improved measure-and-transmit rate.

Signal regeneration using low-power four-wave mixing on silicon chip

Abstract: To meet the increasing demand for higher capacity in optical communications, signal transmission at higher modulation rates and over a broader wavelength range will be required. Signal degradation in the optical channel caused by dispersion, nonlinearity and noise becomes a critical issue as data rates increase. Thus, it is highly desirable to develop broadband, high-speed regeneration devices1. Recent advances in silicon-on-insulator photonic devices offer the potential for highly integrated, robust opto–electronic architectures, and optical processes such as amplification2,3,4, wavelength conversion5,6,7 and amplitude modulation8,9 have already been demonstrated in such structures. In this work, we demonstrate two regeneration schemes using low-power four-wave mixing in a silicon nanowaveguide and compensate for the effects of poor extinction ratio, dispersive broadening and timing jitter. This capability further expands the range of optical functions that can be incorporated into silicon-compatible photonic devices offering a broadband and integrated solution for regeneration.

Space or time adaptive signal processing by neural network models

Abstract: Part I. Starting from the properties of networks with backward lateral inhibitions, we define an algorithm for adaptive spatial sampling of line‐structured images. Applications to character recognition are straightforward.Part II. Let be an array of n sensors, each sensitive to an unknown linear combination of n sources. This is a classical problem in Signal Processing. But what is less classical is to extract each source signal without any knowledge either about those signals or about their combination in the sensors outputs. The only assumption is that the sources are independent.This problem emerged from recent studies on neural networks where any message appears as an unknown mixing of primary entities which are to be ‘‘discovered’’. According to the model of neural networks, we propose an algorithm based on: i − a network of fully interconnected processors (like neurons in a small volume of the Central Nervous System). ii − A law which controls the weights of the interconnections, derived from the Hebb concept for ‘‘Synaptic plasticity’’ in Physiology, and very close to the well know ‘‘stochastic gradient algorithm’’ in Signal Processing.This asociation result in a permanent selfearning mechanism which leads to a continuously up‐dating model of the sensor array information structure.After convergence, the algorithm provides output signals directly proportional to the independent primitive source signals.

Apparatus for transmitting and receiving a signal and method of transmitting and receiving a signal

Abstract: The present invention relates to a method of transmitting and a method of receiving signals and corresponding apparatus. One aspect of the present invention relates to an efficient L1 signaling method for an efficient transmitter and an efficient receiver using the efficient L1 signaling method for an efficient cable broadcasting.

ECG Signal Denoising By Wavelet Transform Thresholding

Abstract: In recent years, ECG signal plays an important role in the primary diagnosis, prognosis and survival analysis of heart diseases. In this paper a new approach based on the threshold value of ECG signal determination is proposed using Wavelet Transform coefficients. Electrocardiography has had a profound influence on the practice of medicine. The electrocardiogram signal contains an important amount of information that can be exploited in different manners. The ECG signal allows for the analysis of anatomic and physiologic aspects of the whole cardiac muscle. Different ECG signals are used to verify the proposed method using MATLAB software. Method presented in this paper is compared with the Donoho's method for signal denoising meanwhile better results are obtained for ECG signals by the proposed algorithm.

Pressure sensor from a PVDF film

Abstract: A new low-cost polymer pressure sensor has been developed. A piezoelectric polyvinylidenefluoride (PVDF) film is used in this sensor as the sensing element. The design of the sensor and the manufacturing are described in detail. The properties of the sensor have been investigated experimentally. The cross-sensitivity to temperature and humidity and the response time were measured and changes of the characteristic curve due to aging were investigated. The influence of different chemicals on the output signal of the pressure sensor are reported and discussed.

Power transmission control device, power transmission device, electronic instrument, and non-contact power transmission system

Abstract: A power transmission control device provided in a power transmission device of a non-contact power transmission system includes an amplitude detection circuit that detects amplitude information that relates to an induced voltage signal of a primary coil, an A/D conversion circuit that performs A/D conversion of the amplitude information, and a control circuit. The A/D conversion circuit performs A/D conversion of a detected voltage detected by the amplitude detection circuit at a conversion timing and determines digital data relating to a reference threshold voltage, the conversion timing being a timing after a given period has expired from a timing when the detected voltage has exceeded a provisional voltage. The control circuit performs at least one of data detection that detects data that has been transmitted from a power reception device by means of load modulation, foreign object detection, and detachment detection using the digital data relating to the reference threshold voltage.

Wireless IC device

Abstract: A wireless IC device includes a wireless IC chip arranged to process a radio signal, a power-supply circuit board that is connected to the wireless IC chip and that includes a power supply circuit including at least one coil pattern, and a radiation plate arranged to radiate a transmission signal supplied from the power-supply circuit board and/or receiving a reception signal to supply the reception signal to the power-supply circuit board. The radiation plate includes an opening provided in a portion thereof and a slit connected to the opening. When viewed in plan from the direction of the winding axis of the coil pattern, the opening in the radiation plate overlaps with an inner area of the coil pattern and the area of the inner area is approximately the same as that of opening.

Electronic information display system employing a plurality of electronic-ink display labels associated with a plurality of manufactured items for displaying information which changes as the manufactured items move through wholesale/retail distribution channels

Abstract: An electronic information display system for installation across wholesale/distribution channels. The system includes a plurality of electronic-ink display labels, associated with a plurality of manufactured items. One or more activation modules are provided across the wholesale/retail distribution channels, for transmitting electromagnetic data signals to the electronic-ink display labels and providing instructions to the updateable electronic-ink display labels. Each electronic-ink display label employs an addressable display assembly including a layer of electronic ink including a bi-stable non-volatile imaging material. The electronic-ink display label includes an integrated circuit structure having a storage element for storing instructions, programs and data, and a programmed processor in communication with storage element. A signal receiving structure receives electromagnetic signals from the activation module, using the antenna structure. The electronic-ink display label displays graphical indicia representing information which changes as the associated manufactured item moves through the wholesale/retail distribution channels.

Kalman filtered Compressed Sensing

Abstract: We consider the problem of reconstructing time sequences of spatially sparse signals (with unknown and time-varying sparsity patterns) from a limited number of linear "incoherent" measurements, in real-time. The signals are sparse in some transform domain referred to as the sparsity basis. For a single spatial signal, the solution is provided by Compressed Sensing (CS). The question that we address is, for a sequence of sparse signals, can we do better than CS, if (a) the sparsity pattern of the signal's transform coefficients' vector changes slowly over time, and (b) a simple prior model on the temporal dynamics of its current non-zero elements is available. The overall idea of our solution is to use CS to estimate the support set of the initial signal's transform vector. At future times, run a reduced order Kalman filter with the currently estimated support and estimate new additions to the support set by applying CS to the Kalman innovations or filtering error (whenever it is "large").

Cordless power-assisted medical cauterization and cutting device

Abstract: A cordless cautery and cutting surgical device includes a modular battery and a surgical handle operable to removably hold the battery. The handle has a cordless radio-frequency-signal generation assembly and a surgical bipolar end effector having jaws and a cutting blade. The signal-generation assembly selectively supplies radio-frequency signal to the end effector when powered for electrocautery of tissue. The handle defines therein an aseptically scalable battery-holding compartment and removably holding the battery. A motor assembly is disposed in the handle and is electrically connected to the battery and/or the signal-generation assembly and is powered and controlled thereby. The motor assembly physically couples to the blade and/or at least one jaw for moving the blade/jaw(s). The second connector part connects the battery to the signal-generation assembly and/or the motor assembly when the battery is removably disposed in the compartment.

LED light communication system

Abstract: An LED light and communication system includes at least one optical transceiver, the optical transceiver including a light support and a processor. The light support has a plurality of light emitting diodes and at least one photodetector attached thereto, the light emitting diodes receiving power from a power source. The processor is in communication with the light emitting diodes and the at least one photodetector, the processor capable of illuminating the light emitting diodes to simultaneously create at least one first light signal, and at least one second light signal, the first light signal being observable to the unaided eyes of an individual and the second light signal not being observable to the unaided eyes of the individual. The second light signal includes at least one data packet. The at least one data packet comprises global positioning system (GPS) location information.

Systems and methods for processing sensor data

Abstract: Systems and methods for processing sensor data are provided. In some embodiments, systems and methods are provided for calibration of a continuous analyte sensor. In some embodiments, systems and methods are provided for classification of a level of noise on a sensor signal. In some embodiments, systems and methods are provided for determining a rate of change for analyte concentration based on a continuous sensor signal. In some embodiments, systems and methods for alerting or alarming a patient based on prediction of glucose concentration are provided.

Adaptive positive feed drilling system

Abstract: A method, apparatus, and computer program product for a drilling operation. In one advantageous embodiment, the drilling operation may comprise a motor, a rotary sensor, and a controller connected to the rotary sensor. The rotary sensor may be capable of generating a signal in response to rotary movement of the drill motor. The controller may be capable of monitoring a speed of the air motor from the signal generated by the rotary sensor and may be capable of identifying a change from a current layer in a stackup to a new layer in the stackup using the signal.

Maximum Eigenvalue Detection: Theory and Application

Abstract: Channel sensing, i.e., detecting the presence of primary users, is a fundamental problem in cognitive radio. Energy detection is optimal for detecting independent and identically distributed (iid) signals, but not optimal for detecting correlated signals. In this paper, a method is proposed based on the sample covariance matrix calculated from a limited number of received signal samples. The maximum eigenvalue of the sample covariance matrix is used as the test statistic. Since the covariance matrix catches the correlations among the signal samples, the proposed method is better than the energy detection for correlated signals. For iid signals, the method approaches to the energy detection. The random matrix theory is used to analyze the method and set the threshold. Similar to energy detection, the methods do not need any information of the source signal and the channel as a priori. Also, no synchronization is needed. Simulations based on wireless microphone signals and iid signals are presented to verify the method.

Optimizing energy transmission in a leadless tissue stimulation system

Abstract: Method and systems for optimizing acoustic energy transmission in implantable devices are disclosed. Transducer elements transmit acoustic locator signals towards a receiver assembly, and the receiver responds with a location signal. The location signal can reveal information related to the location of the receiver and the efficiency of the transmitted acoustic beam received by the receiver. This information enables the transmitter to target the receiver and optimize the acoustic energy transfer between the transmitter and the receiver. The energy can be used for therapeutic purposes, for example, stimulating tissue or for diagnostic purposes.

Control of exciton fluxes in an excitonic integrated circuit.

Abstract: Efficient signal communication uses photons. Signal processing, however, uses an optically inactive medium, electrons. Therefore, an interconnection between electronic signal processing and optical communication is required at the integrated circuit level. We demonstrated control of exciton fluxes in an excitonic integrated circuit. The circuit consists of three exciton optoelectronic transistors and performs operations with exciton fluxes, such as directional switching and merging. Photons transform into excitons at the circuit input, and the excitons transform into photons at the circuit output. The exciton flux from the input to the output is controlled by a pattern of the electrode voltages. The direct coupling of photons, used in communication, to excitons, used as the device-operation medium, may lead to the development of efficient exciton-based optoelectronic devices.

Comparison of the Polar S810i monitor and the ECG for the analysis of heart rate variability in the time and frequency domains

Abstract: The aim of the present study was to compare heart rate variability (HRV) at rest and during exercise using a temporal series obtained with the Polar S810i monitor and a signal from a LYNX(R) signal conditioner (BIO EMG 1000 model) with a channel configured for the acquisition of ECG signals. Fifteen healthy subjects aged 20.9 +/- 1.4 years were analyzed. The subjects remained at rest for 20 min and performed exercise for another 20 min with the workload selected to achieve 60% of submaximal heart rate. RR series were obtained for each individual with a Polar S810i instrument and with an ECG analyzed with a biological signal conditioner. The HRV indices (rMSSD, pNN50, LFnu, HFnu, and LF/HF) were calculated after signal processing and analysis. The unpaired Student t-test and intraclass correlation coefficient were used for data analysis. No statistically significant differences were observed when comparing the values analyzed by means of the two devices for HRV at rest and during exercise. The intraclass correlation coefficient demonstrated satisfactory correlation between the values obtained by the devices at rest (pNN50 = 0.994; rMSSD = 0.995; LFnu = 0.978; HFnu = 0.978; LF/HF = 0.982) and during exercise (pNN50 = 0.869; rMSSD = 0.929; LFnu = 0.973; HFnu = 0.973; LF/HF = 0.942). The calculation of HRV values by means of temporal series obtained from the Polar S810i instrument appears to be as reliable as those obtained by processing the ECG signal captured with a signal conditioner.

A 128 $\times$ 128 Single-Photon Image Sensor With Column-Level 10-Bit Time-to-Digital Converter Array

Abstract: An imager for time-resolved optical sensing was fabricated in CMOS technology. The sensor comprises an array of 128times128 single-photon pixels, a bank of 32 time-to-digital-converters, and a 7.68 Gbps readout system. Thanks to the outstanding timing precision of single-photon avalanche diodes and the optimized measurement circuitry, a typical resolution of 97 ps was achieved within a range of 100 ns. To the best of our knowledge, this imager is the first fully integrated system for photon time-of-arrival evaluation. Applications include 3-D imaging, optical rangefinding, fast fluorescence lifetime imaging, imaging of extremely fast phenomena, and, more generally, imaging based on time-correlated single photon counting. When operated as an optical rangefinder, this design has enabled us to reconstruct 3-D scenes with milimetric precisions in extremely low signal exposure. A laser source was used to illuminate the scene up to 3.75 m with an average power of 1 mW, a field-of-view of 5deg and under 150 lux of constant background light. Accurate distance measurements were repeatedly achieved based on a short integration time of 50 ms even when signal photon count rates as low as a few hundred photons per second were available.

Optimization of Electrochemical Aptamer-Based Sensors via Optimization of Probe Packing Density and Surface Chemistry

Abstract: Electrochemical, aptamer-based (E-AB) sensors, which are comprised of an electrode modified with surface immobilized, redox-tagged DNA aptamers, have emerged as a promising new biosensor platform In order to further improve this technology we have systematically studied the effects of probe (aptamer) packing density, the AC frequency used to interrogate the sensor, and the nature of the self-assembled monolayer (SAM) used to passivate the electrode on the performance of representative E-AB sensors directed against the small molecule cocaine and the protein thrombin We find that, by controlling the concentration of aptamer employed during sensor fabrication, we can control the density of probe DNA molecules on the electrode surface over an order of magnitude range Over this range, the gain of the cocaine sensor varies from 60% to 200%, with maximum gain observed near the lowest probe densities In contrast, over a similar range, the signal change of the thrombin sensor varies from 16% to 42% and optimal signaling is observed at intermediate densities Above cut-offs at low hertz frequencies, neither sensor displays any significant dependence on the frequency of the alternating potential employed in their interrogation Finally, we find that E-AB signal gain is sensitive to the nature of the alkanethiol SAM employed to passivate the interrogating electrode; while thinner SAMs lead to higher absolute sensor currents, reducing the length of the SAM from 6-carbons to 2-carbons reduces the observed signal gain of our cocaine sensor 10-fold We demonstrate that fabrication and operational parameters can be varied to achieve optimal sensor performance and that these can serve as a basic outline for future sensor fabrication

Limits to the sensitivity of a low noise compact atomic gravimeter

Abstract: A detailed analysis of the most relevant sources of phase noise in an atomic interferometer is carried out, both theoretically and experimentally. Even a short interrogation time of 100 ms allows our cold atom gravimeter to reach an excellent short term sensitivity to acceleration of 1.4×10-8g at 1 s. This result relies on the combination of a low phase noise laser system, efficient detection scheme and good shielding from vibrations. In particular, we describe a simple and robust technique of vibration compensation, which is based on correcting the interferometer signal by using the ac acceleration signal measured by a low noise seismometer.

Fundamentals of Signal Processing for Sound and Vibration Engineers

Abstract: An excellent reference for the signal processing field this book includes material on both random signals and deterministic signals in one volume. It combines signal processing theory with worked MATLAB problems and solutions chapter by chapter it integrates topics in continuous, discrete, deterministic, and random signals, for a better overall understanding of the topic. Fundamentals of Signal Processing also provides a structured guide to signal processing for sound and vibration engineers, as well as acting as a reference for those in mechanical, automotive, aerospace, and civil engineering.

Diagnosis of Bearing Faults of Induction Machines by Vibration or Current Signals: A Critical Comparison

Abstract: Early diagnosis of faults in induction machines is an extensively investigated field, for cost and maintenance savings. Mechanical imbalances and bearing faults account for a large majority of faults in a machine, especially for small-medium size machines. Therefore their diagnosis is an intensively investigated field or research. Recently many research activities were focused on the diagnosis of bearing faults by current signal. Stator current components are generated at predictable frequencies related to the electrical supply and mechanical frequencies of bearing faults. However their detection is not always reliable, since the amplitude of fault signatures in the current signal is very low. This paper compares the bearing fault detection capability obtained with vibration and current signals. To this aim a testbed is realized that allows to test vibration and current signal on a machine with healthy or faulty bearings. Signal processing techniques for both cases are reviewed and compared in order to show which procedure is best suited to the different type of bearing faults. The paper contribution is the use of a simple and effective signal processing technique for both current and vibration signals, and a theoretical analysis of the physical link between faults and current components including torque ripple effects. As expected because of the different nature of vibration and current, bearing fault diagnosis is effective only for those fault whose mechanical frequency rate is quite low. Experiments are reported that confirm the proposed approach.

A self-sensing dielectric elastomer actuator

Abstract: A novel self-sensing method based on the dielectric elastomer (DE) actuator/sensor, was successfully developed and evaluated in order to extract accurate displacement information during the actuation process without using any additional sensing device. The proposed self-sensing method is based on a capacitance characteristic of a DE actuator. The DE actuator with a serial external resistor can serve as an electrical high-pass filter. The voltage gained using the high-pass filter, which is virtually built by the DE, varies due to the change of overall capacitance when the DE actuator is expanded electro-mechanically. To realize actuating and sensing simultaneously with a DE actuator, we used a modulation technique to mix signals, which have a low frequency signal for actuating and a high frequency with small amplitude for sensing. Several experiments were performed to verify the usability of the proposed self-sensing method. The results showed a fine resolution and an excellent correlation with the displacements measured by a laser displacement sensor.