Showing papers on "Signal published in 1998"

Prediction of Signal Peptides and Signal Anchors by a Hidden Markov Model

Abstract: A hidden Markov model of signal peptides has been developed. It contains submodels for the N-terminal part, the hydrophobic region, and the region around the cleavage site. For known signal peptides, the model can be used to assign objective boundaries between these three regions. Applied to our data, the length distributions for the three regions are significantly different from expectations. For instance, the assigned hydrophobic region is between 8 and 12 residues long in almost all eukaryotic signal peptides. This analysis also makes obvious the difference between eukaryotes, Gram-positive bacteria, and Gram-negative bacteria. The model can be used to predict the location of the cleavage site, which it finds correctly in nearly 70% of signal peptides in a cross-validated test—almost the same accuracy as the best previous method. One of the problems for existing prediction methods is the poor discrimination between signal peptides and uncleaved signal anchors, but this is substantially improved by the hidden Markov model when expanding it with a very simple signal anchor model.

Data analysis of gravitational-wave signals from spinning neutron stars. I. The signal and its detection

Abstract: We present a theoretical background for the data analysis of the gravitational-wave signals from spinning neutron stars for Earth-based laser interferometric detectors. We introduce a detailed model of the signal including both the frequency and the amplitude modulations. We include the effects of the intrinsic frequency changes and the modulation of the frequency at the detector due to Earth's motion. We estimate the effects of the star's proper motion and of relativistic corrections. Moreover we consider a signal consisting of two components corresponding to a frequency $f$ and twice that frequency. From the maximum likelihood principle we derive the detection statistics for the signal and we calculate the probability density function of the statistics. We obtain the data analysis procedure to detect the signal and to estimate its parameters. We show that for optimal detection of the amplitude modulated signal we need four linear filters instead of one linear filter needed for a constant amplitude signal. Searching for the doubled frequency signal increases further the number of linear filters by a factor of 2. We indicate how the fast Fourier transform algorithm and resampling methods commonly proposed in the analysis of periodic signals can be used to calculate the detection statistics for our signal. We find that the probability density function of the detection statistics is determined by one parameter: the optimal signal-to-noise ratio. We study the signal-to-noise ratio by means of the Monte Carlo method for all long-arm interferometers that are currently under construction. We show how our analysis can be extended to perform a joint search for periodic signals by a network of detectors and we perform a Monte Carlo study of the signal-to-noise ratio for a network of detectors.

System and apparatus for sequential processing of analytes

Abstract: An apparatus and system are provided for simultaneously analyzing a plurality of analytes anchored to microparticles. Microparticles each having a uniform population of a single kind of analyte attached are disposed as a substantially immobilized planar array inside of a flow chamber where steps of an analytical process are carried out by delivering a sequence of processing reagents to the microparticles by a fluidic system under microprocessor control. In response to such process steps, an optical signal is generated at the surface of each microparticle which is characteristic of the interaction between the analyte carried by the microparticle and the delivered processing reagent. The plurality of analytes are simultaneously analyzed by collecting and recording images of the optical signals generated by all the microparticles in the planar array. A key feature of the invention is the correlation of the sequence of optical signals generated by each microparticle in the planar array during the analytical process.

System and method for deriving relative physiologic signals

Abstract: A patient monitoring and/or therapy delivery system and method employing an implantable medical device for sensing absolute physiologic signal values within the body of a patient, e.g., absolute blood pressure, temperature, etc., and an external monitoring device for monitoring and conveying ambient signal values to the implantable medical device, wherein the absolute physiologic signal values and the ambient signal values are combined to derive relative physiologic signal values for storage and/or control of a therapy provided by the implantable medical device. In the context of an implantable physiologic monitor, the relative and optionally, the absolute and/or ambient physiologic signal values are stored in memory for telemetry out to an external programmer in an uplink RF telemetry transmission initiated by medical personnel operating the external programmer. In the context of an implantable therapy delivery device, the relative physiologic signal values are also employed in therapy delivery algorithms.

A comparison of select trigger algorithms for automated global seismic phase and event detection

Abstract: Digital algorithms for robust detection of phase arrivals in the presence of stationary and nonstationary noise have a long history in seismology and have been exploited primarily to reduce the amount of data recorded by data logging systems to manageable levels. In the present era of inexpensive digital storage, however, such algorithms are increasingly being used to flag signal segments in continuously recorded digital data streams for subsequent processing by automatic and/or expert interpretation systems. In the course of our development of an automated, near-real-time, waveform correlation event-detection and location system (WCEDS), we have surveyed the abilities of such algorithms to enhance seismic phase arrivals in teleseismic data streams. Specifically, we have considered envelopes generated by energy transient (STA/LTA), Z -statistic, frequency transient, and polarization algorithms. The WCEDS system requires a set of input data streams that have a smooth, low-amplitude response to background noise and seismic coda and that contain peaks at times corresponding to phase arrivals. The algorithm used to generate these input streams from raw seismograms must perform well under a wide range of source, path, receiver, and noise scenarios. Present computational capabilities allow the application of considerably more robust algorithms than have been historically used in real time. However, highly complex calculations can still be computationally prohibitive for current workstations when the number of data streams become large. While no algorithm was clearly optimal under all source, receiver, path, and noise conditions tested, an STA/LTA algorithm incorporating adaptive window lengths controlled by nonstationary seismogram spectral characteristics was found to provide an output that best met the requirements of a global correlation-based event-detection and location system.

Monitoring technique for accurately determining residual capacity of a battery

Abstract: A battery monitoring system determines an accurate residual capacity of a battery in consideration of variation of battery temperature, amount of battery self-discharge, and amount of battery discharge from a host device, such as a portable computer. The monitoring system further determines a predicted remaining operating time of the device. The battery capacity measuring apparatus includes a microcontroller, a battery pack, a battery temperature detection circuit, a battery voltage detection circuit, a load current detection circuit, and a power saving level detector. The microcontroller is coupled to a host device such that it indicates the battery residual capacity along with the remaining operating time of the device via a display. The microcontroller calculates the residual capacity of the battery based on the detected battery voltage and a correction is made to the calculated residual capacity according to the battery temperature signal and the load current signal, the corrected resultant residual capacity being fed to the host device so as to display the residual capacity of the battery. Also, the microcontroller calculates the remaining operating time of the device based on the detected load current and a correction is made thereto according to the set power saving level of the device, the resultant remaining operating time being fed to the host device so as to display the corrected remaining operating time of the device.

High speed, high density electrical connector

Abstract: A high speed, high density electrical connector for use with printed circuit boards. The connector is in two pieces with one piece having pins and shield plates and the other having socket type signal contacts and shield plates. The shields have a grounding arrangement which is adapted to control the electromagnetic fields, for various system architectures, simultaneous switching configurations and signal speeds, allowing all of the socket type signal contacts to be used for signal transmission. Additionally, at least one piece of the connector is manufactured from wafers, with each ground plane and signal column injection molded into components which, when combined, form a wafer. This construction allows very close spacing between adjacent columns of signal contacts as well as tightly controlled spacing between the signal contacts and the shields. It also allows for easy and flexible manufacture, such as a connector that has wafers intermixed in a configuration to accommodate single ended, point to point and differential applications.

Apparatus and method for treating peripheral vascular disease and organ ischemia by electrical stimulation with closed loop feedback control

Abstract: The present invention discloses techniques for therapeutically treating peripheral vascular disease. A sensor is implemented for sensing the extent of blood flow in a patient's limb or ischemic pain and generating a corresponding sensor signal. The signal is processed to determine the level of spinal cord stimulation or peripheral nerve stimulation to be applied. This information is provided to a signal generator which thereby provides electrical stimulation energy to one or more stimulation leads. Stimulation of the spinal cord, peripheral nerve or neural tissue ganglia thereby improves blood flow, helps restore tissue health and reduces the extent of ischemic pain in the limbs of a PVD patient or organs of other patients. The present invention thereby allows the stimulation to be adjusted automatically to account for changing conditions of the patient throughout the day.

Power/data protocol

Abstract: Provided herein are methods and systems for powering a device, which include providing a data signal and extracting power from the data signal to power the device. The device may be either a device that responds to the data signal or another device. The data signal may vary between at least two data states. The methods and systems may extract power during one or both of the data states. The methods and systems may include a multiplexor. The controlled device may be an RS-485 compliant device, such as an LED system associated with a processor. The data signal may be a DMX-512 signal. The data signal may control a processor for control of the device.

Occupancy sensor and method of operating same

Abstract: A multiple sensing technology-based occupancy sensor. Ultrasonic and infrared sensors are used to produce first and second occupancy estimator signals that are combined using a fusion based detection algorithm to produce a combined estimator signal. The combined estimator is then used to switch electrical loads when the combined estimator signal is above a predetermined threshold. The result is an occupancy sensor that has a very high probability of occupancy detection and a low probability of false tripping. In addition, infrared sensitivity is adjusted based upon an estimation of the background noise in order to minimize the occurrence of false tripping.

Means and method for a synchronous network communications system

Abstract: Nodes on a network are synchronized with each other using a clock transfer system (16). The communications channels between the nodes are then measured (164) and calibrated (163) for optimal bandwidth. The optimized channels and synchronization enable a new form of signaling based on precise control of the frequency, amplitude, and phase of the waveform of the signal. Receiving nodes receive information in order to locate the signal at the frequency, phase and amplitude. Precision control (165, 166) of these parameters also serves as a unique signature of the transmitting node preventing security breaches (162) as the signal's characteristics are unique to the transmitting node. The channel is continuously updated with a precision control system (165, 166) to insure that the nodes are not out of phase.

Optical Cryptosystem Based on Synchronization of Hyperchaos Generated by a Delayed Feedback Tunable Laser Diode

Abstract: We propose a method for encrypting a signal within the high dimensional chaotic fluctuations of the wavelength from a delayed feedback tunable laser diode. Decoding is performed remotely by using a slave laser diode fully synchronized with the master one. No additional synchronization channel is required.

Simultaneous Endocardial Mapping in the Human Left Ventricle Using a Noncontact Catheter Comparison of Contact and Reconstructed Electrograms During Sinus Rhythm

Abstract: Background—Catheter ablation of ventricular tachycardia is limited in part by difficulty in identifying suitable sites for ablation. A noncontact multielectrode array (MEA) has been developed that allows reconstruction of 3360 electrograms, using inverse-solution mathematics, that are superimposed onto a computer-simulated model of the endocardium. This study assesses the accuracy of timing and morphology of reconstructed unipolar electrograms compared with contact unipolar electrograms from the same endocardial site. Methods and Results—The MEA was deployed in the left ventricles of 13 patients (end-diastolic diameters, 61.7±8.4 mm [mean±SD]). We recorded contact electrograms at 76 points equatorial and 32 points nonequatorial to the MEA during sinus rhythm using a catheter-locator signal to record direction and distance from the MEA. Morphology (cross-correlation) and timing of maximum −dV/dt of contact and reconstructed electrograms were compared at different distances from the MEA center to endocardiu...

Real-time 3-D ultrasound imaging using sparse synthetic aperture beamforming

Abstract: A method for real-time three-dimensional (3-D) ultrasound imaging using a mechanically scanned linear phased array is proposed. The high frame rate necessary for real-time volumetric imaging is achieved using a sparse synthetic aperture beamforming technique utilizing only a few transmit pulses for each image. Grating lobes in the two-way radiation pattern are avoided by adjusting the transmit element spacing and the receive aperture functions to account for the missing transmit elements. The signal loss associated with fewer transmit pulses is minimized by increasing the power delivered to each transmit element and by using multiple transmit elements for each transmit pulse. By mechanically rocking the array, in a way similar to what is done with an annular array, a 3-D set of images can be collected in the time normally required for a single image.

Servo controller in scanner of image formation device

Abstract: PROBLEM TO BE SOLVED: To provide a scanner controller of an image formation device which automatically changes the direction of the motor current and provides a rapid and proper scanner travelling performance, when a difference between the motor current and a control target current value at the time of speed reduction in the return operation of the scanner is large. SOLUTION: In an image formation device, a scanner for reading the image data from an original image is reciprocated by a motor M31. A servo controller is constituted of an H-bridge circuit, which rotates the motor in the forward and the reverse direction from a PWM(pulse width modulation) signal which determines the motor speed and a signal determining the direction of rotation, an encoder EC31 installed on a motor shaft, a microcomputer 30 which detects the speed of the rotation and calculates the speed, and controls the speed of the motor from a detection signal of the encoder, a detecting section 40 which detects the value and direction of current in the motor, and a feedback system which controls the speed from the deviation of the motor current value from a target command current value, obtained form the calculation of the motor speed and determines the direction of current to be allowed to flow in the motor from the comparison result between the motor current value and the target command current value and then controls the direction of rotation of the motor.

Image forming device

Abstract: PROBLEM TO BE SOLVED: To make proper correction even if a beam pitch varies owing to thermal expansion of an optical system, etc, and to form a normal image by controlling the beam pitch detected by an optical detector to a specific value SOLUTION: Beams emitted by light source devices 1a and 1b are reflected by a polygon mirror 3 which rotates as shown by an arrow A, passed through an fθ lens 4, a cylindrical lens 22, and a plane mirror 6, and photodetected by a beam sensor 53 first The respective beams are imaged on a photoreceptor drum 5 to scan the photoreceptor drum 5 as shown by an arrow C as the polygon mirror 3 rotates, and then photodetected by a CCD sensor 52 lastly The detection signal is inputted from the beam sensor 53 to a control system and the beams are modulated for a specific print period in synchronism with the detection signal After the print period, the control system having received the detection signal from the CCD sensor having photodetected the beams places a beam shift device in operation at need to correct the beam pitch

Beamforming methods and apparatus for three-dimensional ultrasound imaging using two-dimensional transducer array

Abstract: An ultrasound imaging system includes a two-dimensional array of ultrasound transducer elements that define multiple subarrays, a transmitter for transmitting ultrasound energy into a region of interest with transmit elements of the array, a subarray processor and a phase shift network associated with each of the subarrays, a primary beamformer and an image generating circuit. Each subarray processor includes receive circuitry responsive to transducer signals generated by receive elements of the associated subarray for providing first and second subarray signals. The first subarray signal comprises a sum of first component signals, and the second subarray signal comprises a sum of second component signals. The first and second component signals are derived from the respective transducer signals. The phase shift network phase shifts and combines the first and second subarray signals to provide a phase shifted subarray signal. The primary beamformer delays each of the phase shifted subarray signals by delays that are individually controlled and provides delayed subarray signals which are summed to provide a beamformer signal.

Visual prosthesis and method of using same

Abstract: A visual prosthesis comprises a camera for perceiving a visual image and generating a visual signal output, retinal tissue stimulation circuitry adapted to be operatively attached to the user's retina, and wireless communication circuitry for transmitting the visual signal output to the retinal tissue stimulation circuitry within the eye. To generate the visual signal output the camera converts a visual image to electrical impulses which are sampled to selecting an image at a given point in time. The sampled image signal is then encoded to allow a pixelized display of it. This signal then is used to modulate a radio frequency carrier signal. A tuned coil pair having a primary and a secondary coil are used to transmit and receive the RF modulated visual signal which is then demodulated within the eye. The retinal stimulation circuitry includes a decoder for decoding the visual signal output into a plurality of individual stimulation control signals which are used by current generation circuitry to generate stimulation current signals to be used by an electrode array having a plurality of electrodes forming a matrix. The intraocular components are powered from energy extracted from the transmitted visual signal. The electrode array is attached to the retina via tacks, magnets, or adhesive.

Highly bandwidth efficient communications

Abstract: A discrete multitone stacked-carrier spread spectrum communication method is based on frequency domain spreading including multiplication of a baseband signal by a set of superimposed, or stacked, complex sinusoid carrier waves. In a preferred embodiment, the spreading involves energizing the bins of a large Fast Fourier transform (FFT). This provides a considerable savings in computational complexity for moderate output FFT sizes. Point-to-multipoint and multipoint-to-multipoint (nodeless) network topologies are possible. A code-nulling method is included for interference cancellation and enhanced signal separation by exploiting the spectral diversity of the various sources. The basic method may be extended to include multielement antenna array nulling methods for interference cancellation and enhanced signal separation using spatial separation. Such methods permit directive and retrodirective transmission systems that adapt or can be adapted to the radio environment. Such systems are compatible with bandwidth-on-demand and higher-order modulation formats and use advanced adaptation algorithms. In a specific embodiment the spectral and spatial components of the adaptive weights are calculated in a unified operation based on the mathematical analogy between the spectral and spatial descriptions of the airlink.

Third harmonic generation microscopy

Abstract: Third harmonic generation microscopy is used to make dynamical images of living systems for the first time. A 100 fs excitation pulse at 1.2 μm results in a 400 nm signal which is generated directly within the specimen. Chara plant rhizoids have been imaged, showing dynamic plant activity, and non-fading image characteristics even with continuous viewing, indicating prolonged viability under these THG-imaging conditions.

Image display unit

Abstract: PROBLEM TO BE SOLVED: To sufficiently perform the frame display even by a signal of a short horizontal blanking period in a case when an image signal which has a number of picture elements less than that of a display unit, is to be displayed, by performing the writing of the signal for the frame display in a horizontal direction, within a vertical blanking period of an input image signal. SOLUTION: A source driver 104 is driven in such manner that only a source line of a part corresponding to a frame in a horizontal direction, is ON, and the condition is kept. An enable signal of the source driver 104 is kept in high level to make the writing of an image signal to an picture element corresponding to the frame in the horizontal direction, possible. The driving of a gate driver 105 is started, and the gate lines are successively switched on to perform the writing of the image signal to the picture element corresponding to the frame in the horizontal direction. The image level on this occasion, is kept in a black level when the display of the frame is black. And the input image signal is displayed on a center of a liquid crystal panel 108.

TTS and prosody based authoring system

Abstract: An information signal content authoring system is provided. The authoring system includes a speech analyzer, responsive to a spoken utterance signal provided by a narrator. The spoken utterance signal is representative of information available to the narrator. The speech analyzer generates a speech signal representative of one or more prosodic parameters associated with the narrator. A text-to-speech converter, responsive to a text signal representative of the information available to the narrator, generates a phonetic representation signal from the text signal and synthesizes a speech signal from the text signal. The text-to-speech converter also generates one or more prosodic parameters from the text signal. A spectrum comparator, operatively coupled to the speech analyzer and the text-to-speech converter, compares the spectral parameters of the speech signal generated by the speech analyzer to the speech signal synthesized by the converter and generates a variance signal indicative of a spectral distance between the two speech signals. The variance signal is provided to the text-to-speech converter to adjust the prosodic parameters. An output portion, operatively coupled to the text-to-speech converter, outputs the phonetic representation signal and the prosodic parameters from the converter as a composite encoded signal representative of information content available to the narrator. The output portion further preferably includes an editor, response to editing commands issued by the narrator, for editing at least a portion of the composite encoded signal.

Some general methods for tampering with watermarks

Abstract: Watermarks allow embedded signals to be extracted from audio and video content for a variety of purposes. One application is for copyright control, where it is envisaged that digital video recorders will not permit the recording of content that is watermarked as "never copy". In such a scenario, it is important that the watermark survive both normal signal transformations and attempts to remove the watermark so that an illegal copy can be made. We discuss to what extent a watermark can be resistant to tampering and describe a variety of possible attacks.

High frequency surgical apparatus with tracking of impedance measurement

Abstract: The HF surgical instrument (21) with a HF generator (11), is connectable with at least one active electrode (12) output (13) and at least one neutral electrode (14) - output (15), at which at least one part neutral electrode (14a) of a neutral electrode pair (14a,14b) can be connected. The individual electrodes (14a,14b) of which are connected at an auxiliary voltage with a marked lower frequency than the HF. A monitoring circuit from the auxiliary voltage and the auxiliary current flowing between the part neutral electrodes produces an impedance signal (19) representative for the impedance between the part neutral electrodes. With the exceeding of the first fixed upper alarm threshold (17) and/or a lower second upper alarm threshold (20) matchable to the actual value of the impedance signal, for the impedance signal (19) delivers a HF generator blocking signal (22) and/or an alarm signal (23). The matching of the second alarm threshold (20) is carried out by pressing a SET push button (24).

The handbook of formulas and tables for signal processing

Abstract: Signal processing is a broad and timeless area. The term "signal" includes audio, video, speech, image, communication, geophysical, sonar, radar, medical, and more. Signal processing applies to the theory and application of filtering, coding, transmitting, estimating, detecting, analyzing, recognizing, synthesizing, recording, and reproducing signals. Handbook of Formulas and Tables for Signal Processing a must-have reference for all engineering professionals involved in signal and image processing. Collecting the most useful formulas and tables - such as integral tables, formulas of algebra, formulas of trigonometry - the text includes:Material for the deterministic and statistical signal processing areasExamples explaining the use of the given formulaNumerous definitionsMany figures that have been added to special chaptersHandbook of Formulas and Tables for Signal Processing brings together - in one textbook - all the equations necessary for signal and image processing for professionals transforming anything from a physical to a manipulated form, creating a new standard for any person starting a future in the broad, extensive area of research.

Radio frequency identification tag on flexible substrate

Abstract: An enhanced identification tag (20) produces an identification (ID) signal (38) carrying identification information, capable of being interpreted by an electronic reader device (30). An identification tag (20) in accordance with the invention is characterized by a flexible substrate (22), programmable encoder circuitry (28) formed on said substrate (22) defining identification information, an antenna (24) and signal generator circuitry (26) carried by said substrate (22) responsive to said encoder circuitry (28) for applying a radio frequency signal bearing said identification information (36) to said antenna (24). A preferred tag is fabricated using a printing process to mark a conductive pattern, e.g., comprised of a conductive ink based on silver, carbon, etc., on a flexible substrate (22), plastic type material. In a typical application, the flexible substrate (22) is then preferably used to form a wrist band that can be used to identify an individual to permit, deny or otherwise determine the level of access to an area, e.g., a concert, a work area or other restricted environment.

Systems, methods, and devices for controlling external devices by signals derived directly from the nervous system

Abstract: A system and method control prostheses and other devices with signals received by sensors implanted directly in the brain or other parts of the nervous system of a subject/patient and transmitted to an external receiver. Included in the system are sensors in the form of bundles of small, insulated, flexible wires, configured in a parallel or twisted array, which are used to receive multicellular signals from small clusters of neurons. A new “calibration/adaptation” system is developed, in which the neural signals are cross-correlated with the parameters of a set of standardized or model movements as the subject/patient attempts to emulate the model movements, and on the basis of the correlations the neural signals that are best suited for control of the corresponding movement or movement parameter of the external device are selected. Periodic use of this calibration system compensates for or adapts to uncontrolled changes in neural signal parameters over time, and therefore results in re-selection of the optimal neural channels for better device control. Artificial neural nets are used for mapping the selected neural signals onto appropriate movements or control parameters of the external device.

Theory and application of passive SAW radio transponders as sensors

Abstract: Surface acoustic wave (SAW) radio transponders make it possible to read identification codes or measurement values from a remote location. The decisive advantage of these SAW transponders lies in their passive operation (i.e., no power-supply), and in the possibility of wireless installation at particularly inaccessible locations. The passive SAW transponders are maintenance free. Identification marks respond to an interrogation signal with their nonchanging identification pattern. In wireless SAW sensors the physical or chemical properties to be detected change the propagation characteristics of the SAW. SAW radio transponders are advantageously placed on moving or rotating parts and in hazardous environments such as contaminated or high voltage areas. They also can be used for contactless measurements in high vacuum process chambers, under concrete, extreme heat, or strong radioactive radiation, where the use of conventional sensors is complicated, dangerous, or expensive. In this paper we discuss the principles of wireless passive SAW transponders and present a radio frequency interrogation unit and several passive radio SAW sensors developed for noncontact measurements of temperatures, pressures, torques, and currents.

Integrating digital data with perceptible signals

Abstract: A method for combining digital data with a perceptible program signal. The data stream is modulated onto an electromagnetic signal encoding the perceptible signal; the modulating employs a spread spectrum encoding of the data stream. The modulated program signal is transduced into perceptible form. A capture device receives the perceptible signal, and a decoder extracts the spread spectrum encoded data from the received signal. The method is particularly useful in encoding purchase information or watermarking information into the signal.