Showing papers on "Signal published in 1992"

Estimating and Interpreting The Instantaneous Frequency of a Signal

Abstract: For pt.I see ibid., vol.80, no.4, p.520-38 (1992). The concept of instantaneous frequency (IF) is extended to discrete-time signals. The specific problem explored is that of estimating the IF of frequency-modulated (FM) discrete-time signals embedded in Gaussian noise. Well-established methods for estimating the IF include differentiation of the phase and smoothing thereof, adaptive frequency estimation techniques such as the phase locked loop (PLL), and extraction of the peak from time-varying spectral representations. More recently, methods based on a modeling of the signal phase as a polynomial have been introduced. These methods are reviewed, and their performance compared on both simulated and real data. Guidelines are given as to which estimation method should be used for a given signal class and signal-to-noise ratio (SNR). >

Magnetic interpretation using the 3-D analytic signal

Abstract: A new method for magnetic interpretation has been developed based on the generalization of the analytic signal concept to three dimensions. The absolute value of the analytic signal is defined as the square root of the squared sum of the vertical and the two horizontal derivatives of the magnetic field. This signal exhibits maxima over magnetization contrasts, independent of the ambient magnetic field and source magnetization directions. Locations of these maxima thus determine the outlines of magnetic sources. Under the assumption that the anomalies are caused by vertical contacts, the analytic signal is used to estimate depth using a simple amplitude half-width rule. Two examples are shown of the application of the method. In the first example, the analytic signal highlights a circular feature beneath Lake Huron that has been identified as a possible impact crater. The second example illustrates the continuation of terranes across the Cabot Strait between Cape Breton and Newfoundland in eastern Canada.

Estimating and interpreting the instantaneous frequency of a signal. II. Algorithms and applications

Abstract: For pt.I see ibid., vol.80, no.4, p.520-38 (1992). The concept of instantaneous frequency (IF) is extended to discrete-time signals. The specific problem explored is that of estimating the IF of frequency-modulated (FM) discrete-time signals embedded in Gaussian noise. Well-established methods for estimating the IF include differentiation of the phase and smoothing thereof, adaptive frequency estimation techniques such as the phase locked loop (PLL), and extraction of the peak from time-varying spectral representations. More recently, methods based on a modeling of the signal phase as a polynomial have been introduced. These methods are reviewed, and their performance compared on both simulated and real data. Guidelines are given as to which estimation method should be used for a given signal class and signal-to-noise ratio (SNR). >

Multiresolution Signal Decomposition: Transforms, Subbands, and Wavelets

Abstract: From the Publisher: Multiresolution Signal Composition: Transforms, Subbands, and Wavelets, Second Edition is the first book to give a unified and coherent exposition of orthogonal signal decomposition techniques. Advances in the field of electrical engineering/computer science have occurred since the first edition was published in 1992. This second edition addresses new developments in applications-related chapters, especially in Chapter 4, "Filterbrook Families: Design and Performance," which is greatly expanded. Also included are the most recent applications of orthogonal transforms in digital communications and multimedia. Multiresolution Signal Composition: Transforms, Subbands, and Wavelets, Second Edition is intended for graduate students and research and development practitioners engaged in signal processing applications in voice and image processing, multimedia, and telecommunications.

Surgical operation device

Abstract: The invention relates to a surgical procedures device in connection with a medical procedure, the device comprising an orientation arm (3) adapted to be used for performing and/or guiding the movements required by the procedure, and said orientation arm (3) being protected or protectable by means of a sterile or sterilizable protection means (11), and to which orientation arm (3) or equivalent means a surgical instrument (4), such as a needle, an ultrasonic probe or equivalent means is connected or connectable, and the orientation arm (3) being connected or connectable to the surgical instrument (4) by means of an intermediate piece (12) or equivalent, made of a sterilizable material The intermediate piece (12) and orientation arm (3) comprise identification means (15, 16) for generating an identification signal specific to the surgical instrument and for permitting the identification of the surgical instrument (4)

Combination monophasic action potential/ablation catheter and high-performance filter system

Abstract: A combination catheter for both detecting monophasic action potentials and ablating surface tissue in an in vivo heart of a patient is provided. The apparatus includes a catheter probe having a terminal tip portion (10) and an electrode (20) carried on the tip such that a portion of the tip electrode (20) is exposed to ambient. A reference electrode (50) is spaced along the tip from the first electrode for supplying a reference potential signal. An ablating electrode (30) is located adjacent to but electrically insulated from both the tip (20) and reference (50) electrodes for providing electromagnetic energy to the tip. The electrodes are electrically connected to the proximal end of the catheter through individual conductors or wires (22, 32, and 50) that run through an insulated cable. An electronic filter is provided to permit the recording of MAPs during ablation without radiofrequency interference. The catheter may also include standard mapping and/or pacing electrodes (80 and 75) respectively. The catheter may further include a steering mechanism for positioning the catheter at various treatment sites in the heart, and a structure for holding the tip electrode in substantially perpendicular contact with heart tissue with a positive pressure, and for spacing the reference electrode from the heart tissue.

Optical scanning head

Abstract: The optical scanning head includes at least one trio of light emitting diodes arranged so the LEDs emit light at different angles to create a fan of light. An optical module includes a light shield or "dark room" and a lens/filter assembly which provides control of the depth of focus of the scanner. The optical module is located behind the light source, and the detector, made up of a CCD array is mounted behind the optic module for detecting the light intensity in the reflected beam over a field of view across a bar code symbol. The CCD array generates an electrical signal indicative of the detected light intensity. A DC source or battery provides DC voltage to the LEDs and CCDs in response to a clocked signal which provides a gradual or sequential illumination of the LEDs and coordinates the activation of the CCDs in order to minimize power consumption during scans.

Near‐field differential scanning optical microscope with atomic force regulation

Abstract: We present the design and describe the operation of a scanning probe microscope which simultaneously provides the attractive mode force and near‐field optical images of objects. In this technique, the force signal is used to track the topography, thus allowing the optical signal primarily to show variations in transmissivity. A number of results are presented on the application of the technique to imaging different samples.

Optical investigation of Bloch oscillations in a semiconductor superlattice.

Abstract: We report the study of optical dephazing of Wannier-Stark ladder excitations in a semiconductor superlattice by means of transient degenerate four-wave mixing. We observe pronounced modulations of the signal with a time period varying linearly with the electric field. The time period is found to equal the temporal periodicity of Bloch oscillations, in agreement with theory. In addition, we find that the dephazing time decreases with increasing localization of the Wannier-Stark states, which is attributed to carrier escape out of the lowest miniband.

Transmitter power control system

Abstract: A power control system for a cellular mobile telephone system in which system users communicate information signals between one another via at least one cell-site (12, 14) using code division multiple access spread spectrum communication signals. The power control system controls transmission signal power for each cellular mobile telephone (16, 18) in the cellular mobile telephone system wherein each cellular mobile telephone has an antenna (70), transmitter (84) and receiver (72, 74) and each cell-site also has an antenna (52), transmitter (62) and receiver (54, 56). The signal power of cell-site (12, 14) transmitted signals is measured as received at the mobile unit (16, 18). Transmitter power is adjusted at the mobile unit (16, 18) in an opposite manner with respect to increases and decreases in received signal power. A power control feedback scheme may also be utilized. At the cell-site (12, 14) in communication with the mobile unit (16, 18), the signal power of mobile unit (16, 18) transmitted signals is measured as received at the cell-site (12, 14). A command signal is generated at the cell-site (12, 14) and transmitted to the mobile unit (16, 18) for further adjusting mobile unit transmitter power corresponding to deviations in the cell-site (12, 14) received signal power. The feedback scheme is used to further adjust the mobile unit (16, 18) transmitter power so that mobile unit (16, 18) transmitted signals arrive at the cell-site (12, 14) at a desired power level.

Signal interception: performance advantages of cyclic-feature detectors

Abstract: The problem of detecting the presence of spread-spectrum phase-shift-keyed signals in variable noise and interference backgrounds is considered, and the performances of four detectors are evaluated and compared. The detectors include the optimum radiometer, the optimum modified radiometer that jointly estimates the noise level and detects the signal, and the maximum-SNR spectral-line regenerator for spectral-line frequencies equal to the chip rate and the doubled carrier frequency. It is concluded that the spectral-line regenerators can outperform both types of radiometers by a wide margin. The performance advantages are quantified in terms of receiver operating characteristics for several noise and interference environments and receiver collection times. >

Bipolar RF generator

Abstract: An electrosurgical bipolar RF generator apparatus includes a bipolar electrode. An aperiodic sequence of uniform width bursts of a high frequency signal are electronically synthesized. Substantially identical decaying amplitude envelopes are impressed on the bursts of the high frequency signal. Each of the envelopes has a predetermined rate of change from a preselected initial amplitude. The impressed bursts of the high frequency signal are applied to the electrode. The electrical apparatus operates in a cut mode or a coagulation mode. The apparatus includes a power supply for providing a variable DC voltage, a short circuit detect circuit for detecting a short circuit at the bipolar electrode, and an open circuit detector for detecting an open circuit at the bipolar electrode.

Control interface apparatus

Abstract: This invention comprises a control interface between a machine and a physical object. The invention includes an infrared transmitter for transmitting a first infrared signal to an object. Upon striking the object, the infrared signal is reflected forming a reflected infrared signal. An infrared receiver receives the reflected signal from the object and the reflected signal is transformed into a second signal which may be either an analogue type or a yes/no threshold type, representative of a distance between the object and the receiver. The second signal is coupled to the machine. The apparatus is a cordless touch-free controller interface for use with a machine. The present invention is ideally suited for controlling cursor position for use with computers and also with video games.

Selection of compressed television signals from single channel allocation based on viewer characteristics

Abstract: A plurality of television signals are transmitted and selectively received on a single television channel allocation. Headend apparatus compresses a set of television signals, such as a main program signal and a plurality of different demographically targeted commercials. The plurality of compressed television signals are combined into a combined signal for transmission on a single television channel allocation. A receiver receiving the combined signal identifies characteristics of a television viewer, and selects a particular one of the compressed television signals from the received combined signal depending on the viewer characteristics. The retrieved signal is decompressed for use by a video appliance.

Speech bandwidth extension method and apparatus

Abstract: A speech bandwidth extension method and apparatus analyzes narrowband speech sampled at 8 kHz using LPC analysis to determine its spectral shape and inverse filtering to extract its excitation signal. The excitation signal is interpolated to a sampling rate of 16 kHz and analyzed for pitch control and power level. A white noise generated wideband signal is then filtered to provide a synthesized wideband excitation signal. The narrowband shape is determined and compared to templates in respective vector quantizer codebooks, to select respective highband shape and gain. The synthesized wideband excitation signal is then filtered to provide a highband signal which is, in turn, added to the narrowband signal, interpolated to the 16 kHz sample rate, to produce an artificial wideband signal. The apparatus may be implemented on a digital signal processor chip.

Actuator having electronically controllable tactile responsiveness.

Abstract: An actuator having electronically controllable tactile responsiveness which is flexibly programmable to facilitate provision in a single actuator of torque-position characteristics, such as a selectable number of detents per actuation through its full operative path. A rotary actuator (114) facilitates provision in a single actuator, of torque versus angular position characteristics, such as a selectable number of detents per revolution. The actuator is in communication with a servo motor (116) having a position encoder (118) which outputs position information to a controller (120) that has access to torque-position relation information. The controller outputs a digital torque signal, which is converted to an analog current signal applied to the servo motor (116). The torque, presenting a tactile response to a human interacting with the actuator (114), is sensed as a detent or a plurality of detents.

Sensor, apparatus and method for non-invasive measurement of oxygen saturation

Abstract: A sensor for non-invasive measurement of oxygen saturation using the reflection method comprises a red transmitter (55), an infrared transmitter (58) and a receiver (57). The distances between the transmitters and the receiver are selected such that the length of the light path (60, 61) between the red transmitter (55) and the receiver (57) is substantially equal to the length of the light path (62, 63) between the infrared transmitter (58) and the receiver (57). The sensor comprises a further red transmitter (56) which is used for another application at the human body or another tissue characteristics where the depth of penetration at the various wavelengths is different from the shown example. Together with an appropriate oximeter, manual or automatic adaptation is possible. Further signal improvement may be obtained by autocorrelating the received signal, detecting its frequency and cross-correlating it with a pattern function of the same frequency.

Emergency vehicle alert system

Abstract: An emergency vehicle alert system provides a transceiver for use in emergency vehicles and a receiver for use in non-emergency vehicles. The transceiver is operative in either a receive mode or a transceive mode at the user's choice. In the transceive mode, the transceiver alternates between emergency vehicle alert signal transmission and a receiving function in which the presence of other emergency vehicles may be detected. In the receive mode, the transceiver responds directly to received emergency vehicle alert signals from other vehicles in the same manner as the standard receiving unit. The transceiver produces a signal having encoded information which identifies the emergency vehicle type. The receiver receives and processes the emergency vehicle alert signal to identify the presence of an emergency vehicle and the type of vehicle doing the transmitting.

Microwave sensing of physiological movement and volume change: a review.

Abstract: The ability non-invasively to detect and monitor the movement of tissues and organs from outside the body provides many worthwhile areas of potential biomedical applications. Several non-invasive microwave techniques for contact and remote sensing of circulatory and respiratory movements and volume changes have been developed. In general, these systems consist of a microwave generator, a sampling device, a transmitting-receiving antenna, a set of signal-conditioning and processing devices, and a display unit. They operate at continuous-wave frequencies between 1 and 35 GHz and make use of amplitude and phase information derived from the received signal. The average power density of energy radiated by present systems ranges from approximately 0.001–1.0 mW/cm2. These systems are capable of registering instantaneous changes in fluid volume, pressure pulse, heart rate, and respiration rate in contact with body surface or at distances greater than 30 m, or behind thick layers of non-conductive walls. 1992 Wiley-Liss, Inc.

Integrated communications terminal

Abstract: An integrated communications terminal including a selectable channel demodulator and decoder, a time-division-multiplexed (TDM) channel demodulator and decoder, a data processor and controller, an audio decompressor, a D/A converter, and a data coder and modulator. The terminal is used with a mobile station having a message display, an input device, RF electronics, and an optional transmitter. The selectable channel demodulator outputs a selectable intermediate-frequency signal as in-phase and quadrature-phase signals for decoding by the selectable channel decoder. The TDM channel demodulator generates a frequency offset signal and outputs in-phase and quadrature-phase TDM signals for decoding by the TDM channel decoder as a TDM-data signal. The data processor and controller time-demultiplexes the TDM-data signal as a control signal, a TDM channel and selectable channel look-up table, and paging and message signals, and generates a transmitter frequency command signal, a selectable data rate and frequency command signal, and a TDM data rate and frequency command signal. The audio decompressor outputs a digital audio data signal. The D/A converter outputs analog audio signals. The carrier signal frequency of the transmitter is set by the transmitter frequency command signal generated by the data processor and controller. The data coder and modulator encodes a data signal and then modulates a carrier signal with the coded data signal to create a data-modulated signal. The transmitter amplifies and transmits the data-modulated signal.

Radiation image read-out apparatus.

Abstract: In a radiation image read-out apparatus, a stimulable phosphor sheet, on which a radiation image has been stored, is scanned with a stimulating ray beam, which causes the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The light, which is emitted by part of the stimulable phosphor sheet being scanned with the stimulating ray beam, is photoelectrically detected and converted into an image signal. The beam diameter of the stimulating ray beam is adjusted such that it is larger than the size of each picture element in the radiation image. Each picture element is scanned with the stimulating ray beam by a plurality of scanning steps such that the position, which is scanned, is shifted for different scanning steps. A filtering device is provided, with which a single image signal component representing each picture element is generated from a plurality of image signal components, which are obtained during the plurality of scanning steps for each picture element.

Completely Erasable Phase Change Optical Disk

Abstract: A phase change optical disk using a new quaternary system of Ag-In-Sb-Te as the active layer will be reported. With this disk, "complete erasure" of the recorded signal has been achieved. A carrier-to-noise ratio of 47 dB and an erase ratio of -47 dB were obtained in the two-pass writing-erasing mode with a linear velocity of 7 m/s and a writing power of 11 mW. In the one-pass overwriting mode, a carrier-to-noise ratio greater than 40 dB was obtained and this recorded signal was also completely erased. The peak power and the bias power for the overwriting were 10 mW and 5 mW, respectively. The facts that the widths of the written marks are narrow and that no large crystalline grains are observed in the periphery of the written marks are considered to be the major causes for the high erasability. We also found that the existence of fine crystalline particles in the initialized active layer can be considered to be of great advantage to high sensitivity.

Deconvolution analysis of hormone data.

Abstract: Publisher Summary This chapter evaluates methods of deconvolution analysis that have been applied to a specific topic in biology—namely, the temporal behavior of hormones, metabolites, and substrates in a sampled fluid compartment, such as blood. Such analyses have a significant place in this area of biology, because the time structure of the hormone, metabolite, or substrate concentration signal conveys important information to the target tissue, yields insights into systems regulation, and subserves the homeostasis of an organism. Deconvolution is a mathematical technique that has been utilized in the physical, applied, and natural sciences as a method for estimating the particular behavior of one or more component processes contributing to an observed outcome. Deconvolution would attempt to reconstruct the initial shock impulse from time records of the remote signal. In the field of spectroscopy, the intensity of an emitted wavelength of light measured at some remote point from the light source is influenced by the energy properties of the initial fluorescent signal and attenuation of the emitted signal as it travels to the point of observation. Deconvolution attempts to recover estimates of the intensity of the original fluorescent discharge. Spontaneous variations in measured concentrations of a metabolite, substrate, or hormone over time are controlled by at least two distinct processes (in addition to effects of "noise" in the system), which are as follows: (1) the rate of entry of the constituent into the blood compartment and (2) the magnitude and type of elimination kinetics serving to remove the compound from the circulation. The measurement of a hormone, metabolite, or substrate in a body fluid is always attended by some degree of assay imprecision, is restrained by some level of assay sensitivity (minimal detectable or limiting hormone concentration), and is subject to some particular specificity (the extent to which the assay correctly reports amounts of the substance of interest, and conversely the extent to which it does not falsely report the presence of other substances).

System for measuring the transfer time of a sound-wave in a gas and thereby calculating the temperature of the gas

Abstract: A system for measuring the "time of flight" or transfer time of a sound wave in a gas by using the relation between the gas temperature and the velocity of the sound wave in the gas, and calculating therefrom the temperature of the gas. The system comprises an emitter, which generates a sound which is coherent in phase, at one frequency or a group of frequencies; a self-correlating decoder and a receiver, which is associated with the emitter, and which sends the sound to a filter system and to an assembly controlled by a microprocessor, which processes the signal coming out of the filter system in a shape similar to a Hamming wave shape in order to determine the absolute maximum value and therefrom determine the transfer time. With this knowledge, it is easy to relate the transfer time to the distance traveled between the emitter and receiver and the known properties of the gas, in order to arrive at the temperature of the gas through which the sound has been sent.

Electronic identification system

Abstract: An identification system comprises an interrogator and a number of transponders. The interrogator includes a transmitter (10) for transmitting an interrogation signal to the transponder, and a receiver (16,18,20,22) for receiving a response signal from the transponder. A micro-processor (28) identifies the transponder from data in the response signal. Each transponder comprises a receiving antenna (30) for receiving the interrogation signal, a code generator (36), a transmitting antenna (32), and a modulator (40) connected to the code generator. On receipt of the interrogation signal the transponder repeatedly transmits a response signal containing data which identifies the transponder. The interrogator detects successful identification of any transponder and briefly interrupts the interrogation signal to indicate the successful identification. Each transponder includes a logic circuit (42) responsive to a respective interruption in the interrogation signal to cease transmission of its own response signal.

Method for producing high speed integrated circuits

Abstract: This invention creates a high speed semiconductor interconnect system which contains a plurality of signal traces, each in a flexible printed circuit, and each adhesively sandwiched between or adjacent to a flexible ground circuit and a flexible power circuit. The signal, power and ground circuits are stacked in multilayers and are connected to respective lead fingers and respective die circuits by standard, known methods such as TAB or wire bond and encapsulated in a known way. The ground plane and power plane being adjacent to the signal plane reduces the power-ground loop inductance and thus reduces the package noise. By reducing the inductance, the circuit can have a shorter switching time. Also, by adding the ground plane, the power-ground capacitance is increased, which serves to reduce the effect of power supply fluctuations in the system.

Ultrasonic position indicating apparatus and methods

Abstract: An ultrasonic imaging system employs a processing circuit which enables the imaging system to accurately display the location of an element in a body by utilizing a transducer which provides an electric signal when an ultrasonic wave impinges thereon. The electric signal is processed to determine the maximum amplitude signals during an entire frame of the ultrasonic imaging system. The signals are characterized in terms of the line at which the signal appears or the ray at which the signal appears and the pixel or location along that line. This information regarding ray and pixel serves as X-Y coordinates enabling one to accurately locate the element and transducer on the displayed image by intensifying the display at that location or by adding color or by producing some other visual effect such as blinking, and so on. Thus the disclosed apparatus in its various forms provides ultrasonic position indication without adjustment whereby one shows the exact location of the localizing transducer.

Programmable monitoring system and method

Abstract: A programmable monitoring system for personal use in a home, medical ward, office or other localized area features a radio receiving base unit and one or more low power, radio-frequency battery-powered wireless transmitter units, each capable of transmitting uniquely encoded pulse-encoded serial digital signals at a common high frequency to the base unit. The base unit has a superregenerative receiver and a microcomputer for deciphering and validating the encoded information to ensure that the coded signal originated with a transmitter unit associated with the base unit. The portable transmitters, once activated, send a coded signal to the base unit indicative of a distress or alarm situation or a low battery condition, and which transmitter unit is transmitting. The base unit deciphers the coded signal and automatically contacts a central monitoring station via a telephone link. The base unit sends the serial number of the base unit, and the specific condition requiring attention, i.e., medical, fire, low-battery, etc., to the central monitoring station. A voice message may optionally be generated by the base unit to indicate contact has been made with the monitoring station, and that help is being dispatched. The base unit has battery back-up and a self-test capability to help ensure the system is able and ready to operate when necessary.

Apparatus and method for playing an electronic poker game

Abstract: An electronic poker game apparatus (10) including user-actuated input members (22) and an electronic game control device (42) electrically connected to input members (22) and responsive to user input to simulate play of a poker game. The game control device (42) generates a plurality of signals representing randomly selected cards from a deck of cards to create a poker hand. A bonus signal generator (52) electrically communicates with the game control device (42) and responds to the selection of a predetermined signal representing a predetermined card to randomly effect one of: (i) replacing the predetermined signal with a bonus signal and (ii) retaining the predetermined signal in accordance with odds less than unity. A display screen (16), which is electrically connected to the game control device (42), displays card symbols corresponding to the randomly selected signals and the bonus signal, if present, to indicate progress of the poker game.

Advanced Digital Signal Processing

Abstract: Outline: