Showing papers on "Signal published in 2000"

Simultaneous Measurement of Impulse Response and Distortion with a Swept-Sine Technique

Abstract: A novel measurement technique of the transfer function of weakly not-linear, approximately time-invariant systems is presented. The method is implemented with low-cost instrumentation; it is based on an exponentially-swept sine signal. It is applicable to loudspeakers and other audio components, but also to room acoustics measurements. The paper presents theoretical description of the method and experimental verification in comparison with MLS.

Active matrix electroluminescent display device

Abstract: An active matrix electroluminescent display device has an array of current-driven electroluminescent display elements (20), for example comprising organic electroluminescent material, whose operations are each controlled by an associated switching means (10) to which a drive signal for determining a desired light output is supplied in a respective address period and which is arranged to drive the display element according to the drive signal following the address period. Each switching means comprises a current mirror circuit (24, 25, 30, 32) which samples and stores the drive signal with one transistor (24) of the circuit controlling the drive current through the display element (20) and having its gate connected to a storage capacitance (30) on which a voltage determined by the drive signal is stored. Through the use of current mirror circuits improved uniformity of light outputs from the display elements in the array is obtained.

Battery pack including input and output waveform modification capability

Abstract: A battery pack includes a plurality of electrochemical cells and a control circuit. The battery pack provides power to a tool in the form of a pulse width modulated waveform. The plurality of electrochemical cells provide a total output voltage. The control circuit is coupled to the plurality of electrochemical cells and receives a trigger signal from the tool. In response to the trigger signal, the control circuit determines whether a pulse width of the pulse width modulated waveform requires adjustment. Additionally, the control circuit can be configured to receive an indication of the total output voltage. In this case, the control circuit determines whether the pulse width of the pulse width modulated wavefrom requires adjustment based on the level of the total output voltage.

Principles of magnetic resonance imaging : a signal processing perspective

Abstract: Since its inception in 1971, magnetic resonance imaging (MRI) has developed into a premier tool for anatomical and functional imaging. This textbook provides a clear and comprehensive treatment of MR image formation principles from a signal processing perspective. Coverage includes: mathematical fundamentals; signal generation and detection principles; signal characteristics; signal localization principles; image reconstruction techniques; image contrast mechanisms; image resolution, noise and artifacts; fast-scan imaging; constrained reconstruction; and spatial information encoding. The text contains comprehensive examples and homework problems. It should give students of biomedical engineering, biophysics, chemistry, electrical engineering and radiology a systematic, in-depth understanding of MRI principles.

Device for controlling an electric appliance used in the sterile area during medical operations

Abstract: The invention relates to a device which is used in the sterile area and which is provided for controlling an electric appliance that is provided in the non-sterile area, whereby the sterile area is essentially separated from the non-sterile area by a cloth-like covering means (1) The invention is characterized in that at least one sensor (8) that is sensitive to magnetic fields is provided in the non-sterile area, and a unit that generates a magnetic field is provided in the sterile area In addition, the sensor (8) that is sensitive to magnetic fields and the unit that generates a magnetic field are separated from one another by at least the cloth-like covering means (1) The unit that generates a magnetic field is arranged opposite the sensor (8) that is sensitive to magnetic fields in such a manner that a spatial and/or temporal alteration of the magnetic field induced by the unit that generates a magnetic field can be detected by the sensor (8) that is sensitive to magnetic fields, thus enabling a sensor signal to be generated A control unit (9) is also provided which, according to the sensor signal, generates a control signal for controlling the electric appliance (10)

Small signal stability for parallel connected inverters in stand-alone AC supply systems

Abstract: This paper presents a small-signal analysis for parallel-connected inverters in stand-alone AC supply systems. The control technique of the inverters is based on frequency and voltage droops, which depends on the local variable measurements and does not need control interconnections. Simulation and experimental results show that the system is well represented by the small-signal model. Some root locus plots for the system are provided, which make the stability studies and design easier.

Physiological signal monitoring system

Abstract: A health monitoring and biofeedback system comprising a photoplethysmography (PPG) sensor, a processing device, and a Web site server for determining, displaying and analyzing various cardiovascular parameters. The PPG sensor is installed within a manually operated user input device such as a mouse or keyboard, measures a user's blood volume contour and transmits it to a processing device such as a personal computer or a personal digital assistant (PDA). The system determines a plurality of cardiovascular indices including mean blood pressure, heart rate, body temperature, respiratory rate, and arterial compliance on the basis of signal characteristics of the systolic wave pulse and the systolic reflected wave pulse present within the digital volume pulse derived from the PPG pulse contour. Signal characteristics of the systolic reflected wave pulse can be determined through various pulse analysis techniques including derivative analysis of the digital volume pulse signal, bandpass filtering or respiratory matrix frequency extraction techniques. By subtracting the systolic reflected wave pulse contour from the digital volume pulse contour, characteristics of the systolic wave pulse can also be identified. The system also provides for the accurate determination of systolic and diastolic blood pressure by using a non-invasive blood pressure monitor to calibrate the relationships between arterial or digital blood pressure and characteristics of the user's digital volume pulse contour. In this way, a wide variety of cardiovascular and respiratory data can be obtained. The system also facilitates the transmittal of such data to the system web site for further analysis, storage, and retrieval purposes.

Method and apparatus for measurement processing of satellite positioning system (sps) signals

Abstract: A method and apparatus is disclosed for measurement processing of Satellite Positioning System (SPS) signals. A plurality of SPS signals from a corresponding plurality of SPS satellites are received in an SPS receiver. The signal environment corresponding to the location in which the SPS receiver is located is characterized to produce signal environment data. In one exemplary embodiment, an information source, such as a cellular network based database, is searched to retrieve the signal environment data given an approximate location of the GPS receiver. This approximate location may be specified by a location of a cell site which is in cellular radio communication with a cellular communication device which is co-located with the GPS receiver. One or more parameters related to signal characteristics of the satellite signals are defined. Threshold values for the parameters are determined using the signal environment data. Code phases corresponding to times of arrival of respective satellite signals from the plurality of satellites are measured. The data representing measured times of arrival are examined using threshold values for the parameters to produce a set of times of arrival from which a location fix for the GPS receiver is calculated. Other methods and apparatuses for other embodiments of the invention are also described.

Stochastic focusing: fluctuation-enhanced sensitivity of intracellular regulation.

Abstract: Many regulatory molecules are present in low copy numbers per cell so that significant random fluctuations emerge spontaneously. Because cell viability depends on precise regulation of key events, such signal noise has been thought to impose a threat that cells must carefully eliminate. However, the precision of control is also greatly affected by the regulatory mechanisms' capacity for sensitivity amplification. Here we show that even if signal noise reduces the capacity for sensitivity amplification of threshold mechanisms, the effect on realistic regulatory kinetics can be the opposite: stochastic focusing (SF). SF particularly exploits tails of probability distributions and can be formulated as conventional multistep sensitivity amplification where signal noise provides the degrees of freedom. When signal fluctuations are sufficiently rapid, effects of time correlations in signal-dependent rates are negligible and SF works just like conventional sensitivity amplification. This means that, quite counterintuitively, signal noise can reduce the uncertainty in regulated processes. SF is exemplified by standard hyperbolic inhibition, and all probability distributions for signal noise are first derived from underlying chemical master equations. The negative binomial is suggested as a paradigmatic distribution for intracellular kinetics, applicable to stochastic gene expression as well as simple systems with Michaelis–Menten degradation or positive feedback. SF resembles stochastic resonance in that noise facilitates signal detection in nonlinear systems, but stochastic resonance is related to how noise in threshold systems allows for detection of subthreshold signals and SF describes how fluctuations can make a gradual response mechanism work more like a threshold mechanism.

Suprathreshold stochastic resonance in multilevel threshold systems

Abstract: A new form of stochastic resonance (SR) that occurs in multilevel threshold signal detectors is reported. In contrast to classical SR, which extends the dynamic range of threshold detectors to subthreshold signal levels, this new form of SR extends the dynamic range to suprathreshold signal strengths. The effect is most dominant, and can outperform networks based on standard engineering design, when all thresholds adapt to the dc level of the signal. This has an interesting analogy to dc adaptation in neurons. The possible connection between these two effects is discussed.

Electromagnetic position single axis system

Abstract: A system for determining the position of a medical device having a sensor comprises a plurality of field radiators wherein each field radiator has a plurality of radiator elements. Each radiator element generates a magnetic field such that each magnetic field is distinct from one another due to the use of a different frequency through simultaneous energizing of the radiator elements. A signal processor is operatively connected to the field radiators and the sensor of the medical device for receiving a sensing signal from the sensor indicative of the magnetic field sensed at the sensor. Alternative field radiator arrangements are also provided in conjunction with a novel algorithm utilizing a global convergent technique.

Method and apparatus combining a tracking system and a wireless communication system

Abstract: System for tracking mobile tags. Cell controllers with multiple antenna modules generate a carrier signal which is received by the tags. Tags shift the frequency of the carrier signal, modulate an identification code onto it, and transmit the resulting tag signal at randomized intervals. The antennas receive and process the response, and determine the presence of the tags by proximity and triangulation. The recursive-least squares (RLS) technique is used in filtering received signals. Distance of a tag from an antenna is calculated by measuring the round trip signal time. The cell controllers send data from the antenna to a host computer. The host computer collects the data and resolves them into positional estimates. A combined infrastructure including a wireless communication system and the local positioning system is also disclosed.

Indicators and illuminators using a semiconductor radiation emitter package

Abstract: A vehicle lamp assembly (209) includes a housing (202) and an LED lamp (218) carried in the housing. A signal mirror (100) includes a mirror (222) and an LED lamp. The LED lamp includes a heat extraction member (400).

Interventive-diagnostic device

Abstract: Apparatus for improving health of a user is provided, including a first sensor, adapted to measure a first physiological variable, which is indicative of a voluntary action of the user. A second sensor is adapted to measure a second physiological variable, which is substantially governed by an autonomic nervous system of the user. Circuitry is adapted to receive respective first and second sensor signals from the first and second sensors, and, responsive thereto, to generate an output signal which directs the user to modify a parameter of the voluntary action.

A computationally efficient multipitch analysis model

Abstract: A computationally efficient model for multipitch and periodicity analysis of complex audio signals is presented. The model essentially divides the signal into two channels, below and above 1000 Hz, computes a "generalized" autocorrelation of the low-channel signal and of the envelope of the high-channel signal, and sums the autocorrelation functions. The summary autocorrelation function (SACF) is further processed to obtain an enhanced SACF (ESACF). The SACF and ESACP representations are used in observing the periodicities of the signal. The model performance is demonstrated to be comparable to those of recent time-domain models that apply a multichannel analysis. In contrast to the multichannel models, the proposed pitch analysis model can be run in real time using typical personal computers. The parameters of the model are experimentally tuned for best multipitch discrimination with typical mixtures of complex tones. The proposed pitch analysis model may be used in complex audio signal processing applications, such as sound source separation, computational auditory scene analysis, and structural representation of audio signals. The performance of the model is demonstrated by pitch analysis examples using sound mixtures which are available for download at http://www.acoustics.hut.fi/-ttolonen/pitchAnalysis/.

Methods and apparatus for high-speed longitudinal scanning in imaging systems

Abstract: An imaging system (2) wherein an optical signal (185, 195) is transmitted to both a sample (25) to be measured and a rotating element (175) which is calibrated to the system. A return signal (186, 196) is detected by the system, and a scan analyzer and correction unit (160) uses the system calibration information along with synchronization information (177, 171) to correct for return signal degradation or errors due to imperfections in the rotating element (175) in real time. This allows for an accurate measurement of the sample (25). The system (2) can also include a coarse path-length adjustment unit (45) to allow the system to track a region of interest within a sample (25) to further allow for accurate sample measurement.

Handbook of Neural Network Signal Processing

Abstract: From the Publisher: The use of neural networks is permeating every area of signal processing. They can provide powerful means for solving many problems, especially in nonlinear, real-time, adaptive, and blind signal processing. The Handbook of Neural Network Signal Processing brings together applications that were previously scattered among various publications to provide an up-to-date, detailed treatment of the subject from an engineering point of view.The authors cover basic principles, modeling, algorithms, architectures, implementation procedures, and well-designed simulation examples of audio, video, speech, communication, geophysical, sonar, radar, medical, and many other signals. The subject of neural networks and their application to signal processing is constantly improving. You need a handy reference that will inform you of current applications in this new area. The Handbook of Neural Network Signal Processing provides this much needed service for all engineers and scientists in the field.

Control system for a marine vessel

Abstract: A control system for a marine vessel incorporates a marine propulsion system that can be attached to a marine vessel and connected in signal communication with a serial communication bus and a controller. A plurality of input devices and output devices are also connected in signal communication with the communication bus and a bus access manager, such as a CAN Kingdom network, is connected in signal communication with the controller to regulate the incorporation of additional devices to the plurality of devices in signal communication with the bus whereby the controller is connected in signal communication with each of the plurality of devices on the communication bus. The input and output devices can each transmit messages to the serial communication bus for receipt by other devices.

Self-powered medical device

Abstract: A self-powered medical device, which is operated independently of the public utility network, has at least one voltage source, a signal input for accepting an analog input signal and a signal processing unit. The sampling rate for the input signal or the clock frequency of at least one digital component can be varied. Therefore, the energy demand can be reduced according to the requirements of the signal processing or when the discharge state of the voltage source requires a reduction.

Discrete chirp-Fourier transform and its application to chirp rate estimation

Abstract: The discrete Fourier transform (DFT) has found tremendous applications in almost all fields, mainly because it can be used to match the multiple frequencies of a stationary signal with multiple harmonics. In many applications, wideband and nonstationary signals, however, often occur. One of the typical examples of such signals is chirp-type signals that are usually encountered in radar signal processing, such as synthetic aperture radar (SAR) and inverse SAR imaging. Due to the motion of a target, the radar return signals are usually chirps, and their chirp rates include the information about the target, such as the location and the velocity. In this paper, we study discrete chirp-Fourier transform (DCFT), which is analogous to the DFT. Besides the multiple frequency matching similar to the DFT, the DCFT can be used to match the multiple chirp rates in a chirp-type signal with multiple chirp components. We show that when the signal length N is prime, the magnitudes of all the sidelobes of the DCFT of a quadratic chirp signal are 1, whereas the magnitude of the mainlobe of the DCFT is /spl radic/N. With this result, an upper bound for the number of the detectable chirp components using the DCFT is provided in terms of signal length and signal and noise powers. We also show that the N-point DCFT performs optimally when N is a prime.

Interior rearview mirror sound processing system

Abstract: A digital sound processor is provided to enhance the vocal to non-vocal noise ratio of the signal processed by a vehicle audio system such as a cellular telephone, emergency communication device, or other audio device. Optionally, an indicator is provided for use with the vehicular audio system in order to provide a user of the audio system with a status signal relating to a reception quality of a vocal signal from the user. The microphone of the audio system may be mounted within an accessory module, which may be mounted to an interior surface of a vehicle windshield. The accessory module provides a fixed orientation of the microphone and is easily installed to the vehicle as it is manufactured or as an aftermarket device. The indicator may be mounted at the accessory module or elsewhere at the mirror assembly.

Synchronization of chaotic semiconductor laser dynamics on subnanosecond time scales and its potential for chaos communication

Abstract: We present experimental evidence for the synchronization of two semiconductor lasers exhibiting chaotic emission on subnanosecond time scales. The transmitter system consists of a semiconductor laser with weak to moderate coherent optical feedback and therefore exhibits chaotic oscillations. The receiver system is realized by a solitary semiconductor laser in which a fraction of the transmitter signal is coherently injected. We find that for a considerably large parameter range, synchronized receiver output can be achieved. We discuss the physical mechanism and demonstrate that the receiver acts as a chaos pass filter, which reproduces the chaotic fluctuations of the transmitter laser, but suppresses additionally encoded signals. Signal extraction at frequencies of up to 1 GHz has been achieved. Thus we provide a simple and robust optical chaos synchronization system that is promising for the realization of communication by sending signals with chaotic carriers.

Optical transmission system

Abstract: PROBLEM TO BE SOLVED: To decrease the number of times of transmission of a reset signal for a network which decides the topology of a bus in compliance with, e.g. the IEEE 1394 to a minimum number of times in a communication network, such as a LAN. SOLUTION: An optical transmitter 1 (2, 11) is a device that optically transmits a twisted pair signal used for a network such as a LAN and a serial bus and consists mainly of a transceiver section 101 that sends/receives data to/from a terminal 100, a code conversion section 102, that encodes data received from the transceiver section 101 into optical transmission data, an optical transmission section 103 and an optical reception section 104 that send/receive data to/from other optical transmitter being a communication opposite party, and optical data detection section 105 that detects a level of a signal received by the optical reception section 104, a state notice section 106 that informs the terminal equipment 100 of the communication state, and an optical link generating section 107 that generates prescribed data, when the optical transmission is in shielded state.

Doppler Ultrasound: Physics, Instrumentation and Signal Processing

Abstract: Preface. Preface to first Edition. Plates. Introduction. Blood Flow. Physics of Ultrasound Propagation. Doppler Systems: A General Overview. Ultrasonic Transducers, Fields and Beams. Signal Detection and Pre--processing: CW and PW Doppler. The Doppler Power Spectrum. Doppler Signal Processors: Theoretical Considerations. Waveform Analysis and Pattern Recognition. Colour Flow Imaging (CFI) Systems. Signal Processing for Colour Flow Imaging. Volumetric Blood Flow Measurement. Miscellaneous Doppler Techniques. Safety Considerations in Doppler Ultrasound. Appendices. Index.

Triggerable remote controller

Abstract: A triggerable remote controller is disclosed which includes a trigger signal including a command, a GPS processor coupled to the trigger signal, a position signal carrying position information generated by the GPS processor in response to the trigger signal, a telemetry transmitter coupled to the position signal, a telemetry transmit signal transmitted by the telemetry transmitter, the telemetry transmit signal carrying the position information, a trigger signal controller coupled to the trigger signal, an actuator coupled to the trigger signal controller, the trigger signal controller being configured to attempt to activate the actuator depending on the command. A sensor may also be coupled to the trigger signal controller and the trigger signal controller may be configured to attempt to access the sensor. A GPS antenna embedded in a grommet-shaped housing is also disclosed.

System and method for signaling a weather alert condition to a residential environment

Abstract: As system and method are provided for communicating weather conditions to remote locations, such as inside of residential homes, offices, or businesses. In accordance with one embodiment, a modified smoke detector is provided having an integrated RF receiver for receiving message packets containing information that may be conveyed through its speaker, buzzer, or other sound-emanating device. In accordance with another embodiment, a system is provided. The system which may include a mechanism for detecting a weather condition, a wireless transmitter in communication with the mechanism for detecting a weather condition, wherein the wireless transmitter configured to receive a signal from the means for detecting a weather condition and transmit a corresponding signal via electromagnetic waves. The system may also include a receiver remotely located from the wireless transmitter, the receiver configured to receive the electromagnetic signal transmitted from the smoke detector. Finally, the system may include a sound-emanating device, and a sound control mechanism for controlling the sound-emanating device, wherein the sound control mechanism is responsive to the electromagnetic signal received by the receiver. In yet another embodiment, a method is provided. The method includes steps of: (1) determining that a weather condition (e.g., severe weather condition) exists, (2) transmitting a radio frequency (RF) signal containing information about the weather condition, (3) receiving the RF signal with a RF receiver disposed in a smoke detector (or other device), and (4) sounding a buzzer (or other sound emanating device) in response to receiving the RF signal.

Multifrequency complementary phase-coded radar signal

Abstract: A multifrequency radar signal is considered It uses M subcarriers simultaneously The subcarriers are phase modulated by M different sequences that constitute a complementary set Such a set can be constructed, for example, from the M cyclic shifts of a perfect phase-coded sequence of length M (eg P4) The subcarriers are separated by the inverse of the duration of a phase element t/sub b/, yielding orthogonal frequency division multiplexing (OFDM), well known in communications A single pulse of such a signal exhibits a thumbtack ambiguity function with delay resolution of t/sub b//M The power spectrum is relatively flat, with width of M/t/sub b/ The signal can be constructed by power combining M fixed-amplitude signals The resulting signal, however, is of variable amplitude The peak-to-mean envelope power ratio can be maintained below 2 A train of complementary pulses and a weight function along the frequency axis are useful for further sidelobe reduction

Method and System for Navigating a Catheter Probe in the Presence of Field-Influencing Objects

Abstract: A system for and method of determining and compensating for the effect of a field influencing object on a field sensor, preferably a coil, that is within a navigational domain. The navigational domain contains navigational magnetic energy and disturbing magnetic energy, and the field influencing object produces the disturbing magnetic energy in response to the navigational magnetic energy. The correction system includes a first transmitter for projecting into the navigational domain field energy in a first waveform sufficient to induce a first signal value in the sensing coil. The system also includes a second transmitter for projecting into the navigational domain field energy in a second waveform sufficient to induce a second signal value in the sensing coil. The system further includes a signal processor for receiving the second signal value to determine the effect of the electrically conductive object on the field sensor.

Patient position detection apparatus for a bed

Abstract: An apparatus is provided for detecting a position of a body on a support surface (38) of a bed (10). The apparatus includes at least one first sensor (70) coupled to the bed (10) and at least one second sensor (104) located adjacent the support surface (38). The at least one first sensor (70) has an output signal which is variable in response to changes in a weight applied to the support surface (38). The at least one second sensor (104) has an output signal which is variable in response to changes in the position of the body on the support surface (38). The apparatus also includes a controller (50) having inputs configured to receive the output signals from the first and second sensors (70, 104). The controller (50) is configured to monitor the output signals, to provide an indication of changes in the position of the body relative to the support surface (38), and to provide an indication if the body exits the support surface (38).