Showing papers on "Signal published in 1990"
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03 Apr 1990
TL;DR: The results of applying this algorithm to a number of well-known signals are shown and some of the invariance and noise properties of the algorithm are derived and verified by simulation.
Abstract: A simple algorithm is derived that permits on-the-fly calculation of the energy required to generate, in a certain sense, a signal. The results of applying this algorithm to a number of well-known signals are shown. Some of the invariance and noise properties of the algorithm are derived and verified by simulation. The implementation of the algorithm and its application to speech processing are briefly discussed. >
1,221 citations
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TL;DR: A model of catecholamine effects in a network of neural-like elements is presented, which shows that changes in the responsivity of individual elements do not affect their ability to detect a signal and ignore noise but the same changes in cell responsivity do improve the signal detection performance of the network as a whole.
Abstract: At the level of individual neurons, catecholamine release increases the responsivity of cells to excitatory and inhibitory inputs. A model of catecholamine effects in a network of neural-like elements is presented, which shows that (i) changes in the responsivity of individual elements do not affect their ability to detect a signal and ignore noise but (ii) the same changes in cell responsivity in a network of such elements do improve the signal detection performance of the network as a whole. The second result is used in a computer simulation based on principles of parallel distributed processing to account for the effect of central nervous system stimulants on the signal detection performance of human subjects.
760 citations
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TL;DR: A correction method is proposed for proton spectroscopy, which uses the signal of prominent water protons as a reference for the water‐suppressed signal, and has a good resolution as shown by phantom measurements and brain and muscle spectra of volunteers.
Abstract: Spatially localized methods in spectroscopy often operate with magnetic field gradients for volume selection. The eddy currents induced by these gradients produce time-dependent shifts of the resonance frequency in the selected volume, which results in a distortion of the spectrum after Fourier transformation. In whole-body systems the complete compensation of eddy currents is a difficult procedure. To avoid this, a correction method is proposed for proton spectroscopy, which uses the signal of prominent water protons as a reference for the water-suppressed signal. The correction is performed in the time domain, dividing the water-suppressed signal by the phase factor of the water signal for each data point. The corrected spectra have a good resolution as shown by phantom measurements and brain and muscle spectra of volunteers.
585 citations
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01 Jun 1990TL;DR: In this article, an electronic endoscope was provided with an image sensor at the distal end of the scope and an angle operation portion adjacent to the image sensor, and a scope unit coupled with the electronic scope, including an endoscopic operation switch mechanically connected to the scope.
Abstract: In an electronic endoscope apparatus, comprising: there are provided an electronic scope having an image sensor at a distal end thereof and an angle operation portion adjacent to the image sensor; a scope unit coupled with the electronic scope, including an endoscopic operation switch mechanically connected to the electronic scope, a scope computer for processing a switch operation signal derived from the endoscopic operation switch so as to obtain first use-history data on the operation switch, and a memory device for temporarily storing the first use-history data therein; and, a main unit including a signal processor for processing an image signal derived from the image sensor so as to produce an endoscopic image signal of a biological body under medical examination, a system computer for fetching the use-history data on the operation switch from the memory device via the scope computer, and a display unit for selectively displaying an endoscopic image of the biological body in response to the endoscopic image signal and use-history information in response to the fetched used-history data.
503 citations
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TL;DR: A novel approach to the general problem of signal parameter estimation is described, and although discussed in the context of direction-of-arrival estimation, ESPRIT can be applied to a wide variety of problems.
Abstract: High-resolution signal parameter estimation is a problem of significance in many signal processing applications. Such applications indude direction-of-arrival estimation, system identification, and time series analysis. A novel approach to the general problem of signal parameter estimation is described. Although discussed in the context of directionof-
arrival estimation, ESPRIT can be applied to a wide variety of problems. It exploits an underlying rotational invariance among signal subspaces
induced by an array of sensors with a translational invariance structure. The technique, when applicable, manifests significant performance and computational advantages over previous algorithms such as Burg's maximum entropy method, Capon's maximum likelihood method, and Schmidt's multiple signal classification.
461 citations
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12 Apr 1990
TL;DR: A hand-held joystick has spaced-apart groups of accelerometers and is free to move or rotate on multiple axes as mentioned in this paper, with each group having three mutually perpendicular accelerometers, with each one producing an electrical signal responsive to linear acceleration along one axis.
Abstract: A hand-held joystick has spaced-apart groups of accelerometers and is free to move or rotate on multiple axes. Each group has, for example, three mutually perpendicular accelerometers, with each one producing an electrical signal responsive to linear acceleration along one axis. The signals are combined to derive a definition of acceleration of the joystick along the three mutually perpendicular linear axes and/or rotation about these axes. The combined signal is used by an electrical control system which provides input to a device being controlled. The signal to the device under control is responsive to the motion of the joystick.
335 citations
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TL;DR: The results for a simulated binary 8-Gb/s system show that simple techniques can be used to reduce intersymbol interference substantially, thereby increasing the system margin by several decibels.
Abstract: The potential for electrical signal processing to mitigate the effect of intersymbol interference in long-haul fiber-optic systems is discussed. Intersymbol interference can severely degrade performance and consequently limit both the maximum distance and data rate of the system. Several techniques for reducing intersymbol interference in single-mode fiber systems with single-frequency lasers are presented, and those techniques which are appropriate at high data rates in direct coherent detection systems are identified. The performances of linear equalization (tapped delay lines), nonlinear cancellation (variable threshold detection), maximum-likelihood detection, coding, and multilevel signaling are analyzed. The results for a simulated binary 8-Gb/s system show that simple techniques can be used to reduce intersymbol interference substantially, thereby increasing the system margin by several decibels. A six-tap linear equalizer increases the dispersion-limited distance (due to chromatic or polarization dispersion) by 20% (or reduces the optical power penalty by as much as a factor of two) in direct detection systems, even when the distortion is nonlinear. A nonlinear cancellation technique (adjusting the decision threshold in the detector based on previously detected bits) can more than double the dispersion-limited distance and/or data rate. >
328 citations
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TL;DR: Signals are never perfectly bandlimited, nor can the authors construct a perfect reconstruction filter, but they can get as close as they want in a prescribed manner.
Abstract: Even though a signal is sampled, we may have certain rules about inferring the values between the sample points The most common assumption made in signal processing is that the signal is bandlimited to an extent consistent with the sampling rate, ie that the values change smoothly between samples The Sampling Theorem guarantees that a continuous signal can be reconstructed perfectly from its samples if the signal was appropriately bandlimited prior to sampling [Oppenheim 75] Practically speaking, signals are never perfectly bandlimited, nor can we construct a perfect reconstruction filter, but we can get as close as we want in a prescribed manner
302 citations
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03 Jul 1990
TL;DR: In this paper, a frequency synthesiser comprising a phase-locked loop having a reference oscillator coupled to a first input of a comparator, a voltage controlled oscillator (VCO) for providing an output signal, which output signal is fed back by way of a divider circuit, or dividing the output fequency by a factor N to a second input of said comparator.
Abstract: A frequency synthesiser comprising a phase locked loop having a reference oscillator (8) coupled to a first input of a comparator (6), a voltage controlled oscillator (VCO) (2) for providing an output signal, which output signal is fed back by way of a divider circuit (4) or dividing the output fequency by a factor N to a second input of said comparator, the output of the comparator being applied to a control input of the VCO, and including input means for applying a modulating signal in binary format via integrator means (26) for control of the divider circuit, and means having a predetermined transfer function (22) coupling said modulating signal to the control input of the VCO whereby to provide a modulation of the output signal in desired format.
272 citations
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TL;DR: A system using two Polaroid transducers is described that correctly discriminates between corners and planes for inclination angles within +or-10 degrees of the transducer orientation, allowing the system to operate over an extended range.
Abstract: A multitransducer, pulse/echo-ranging system is described that differentiates corner and plane reflectors by exploiting the physical properties of sound propagation. The amplitudes and ranges of reflected signals for the different transmitter and receiver pairs are processed to determine whether the reflecting object is a plane or a right-angle corner. In addition, the angle of inclination of the reflector with respect to the transducer orientation can be measured. Reflected signal amplitude and range values, as functions of inclination angle, provide the motivation for the differentiation algorithm. A system using two Polaroid transducers is described that correctly discriminates between corners and planes for inclination angles within +or-10 degrees of the transducer orientation. The two-transducer system is extended to a multitransducer array, allowing the system to operate over an extended range. An analysis comparing processing effort to estimation accuracy is performed. >
268 citations
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03 Jul 1990
TL;DR: In this paper, a video transmission system for facilitating transmission of video and control signals between different locations in a residence using existing telephone wiring is presented. But it does not address the problem of interference with telephone communications.
Abstract: A video transmission system for facilitating transmission of video and control signals, particularly infrared remote control signals, between different locations in a residence using existing telephone wiring. Simultaneous transmission of signals of both types over active telephone lines is possible without interference with telephone communications. Transmission succeeds without requiring special treatement of the video signals beyond RF conversion, despite signal attenuation inherent in transmission over the telephone line media. Two or more video sources may be tied into the system, and selected as desired. Remote control signals generated in one room may be utilized without requiring a clear line of sight between the remote control device and the receiver.
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TL;DR: It is shown that whenever the solution to the signal flow equations of the Random Network exists, it is unique and therefore that the network has a well-defined steady-state behavior.
Abstract: In a recent paper [1] we have introduced a new neural network model, called the Random Network, in which "negative" or "positive" signals circulate, modelling inhibitory and excitatory signals. They are summed at the input of each neuron and constitute its signal potential. The state of each neuron in this model is its signal potential, while the network state is the vector of signal potentials at each neuron. If its potential is positive, a neuron fires, and sends out signals to the other neurons of the network or to the outside world. As it does so its signal potential is depleted. We have shown that in the Markovian case, this model has product form, i.e. the steady-state probability distribution of its potential vector is the product of the marginal probabilities of the potential at each neuron. The signal flow equations of the network, which describe the rate at which positive or negative signals arrive to each neuron, are non-linear, so that their existence and uniqueness is not easily established except for the case of feedforward (or backpropagation) networks [1]. We examine two sub-classes of networks: balanced, and damped networks and obtain stability conditions in each case. A hardware implementation of these networks is also suggested.
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TL;DR: In this paper, a tactile aid for deaf individuals includes a conveniently wearable array of vibration transducers mounted on a flexible carrier strip so as to be positionally biased toward the individuals's skin, each transducers includes an enclosed magnetically vibratable cantilevered beam, an angled mounting slot to effect the positional bias mounting on the strip, and contact pads rather than conventional pin connectors to both reduce mass and facilitate electrical connection to contact pads on carrier strips in the form of printed circuit boards.
Abstract: A tactile aid for deaf individuals includes a conveniently wearable array of vibration transducers mounted on a flexible carrier strip so as to be positionally biased toward the individuals's skin. Each transducer includes an enclosed magnetically vibratable cantilevered beam, an angled mounting slot to effect the positional bias mounting on the strip, and contact pads rather than conventional pin connectors to both reduce mass and facilitate electrical connection to contact pads on carrier strips in the form of printed circuit boards. Received acoustic signals are processed in at least first and second formant circuits each sub-divided into plural sub-bands corresponding to the number of transducers. In each formant circuit the corresponding formant frequency and amplitude are measured, averaged over a predetermined number of cycles, and a voltage corresponding to the measured amplitude is provided on a corresponding sub-hand channel to pulse width modulate a pulse train employed to excite the transducers. Spectral resolution can be increased by averaging the amplitude/frequency measurements over fewer cycles. Glottal pulses in the speech signal are monitored to provide a glottal rate signal at a stepped down frequency related to the actual glottal rate. The channel amplitude is modulated by the glottal signal to cause alternation of transducer excitation at the related glottal rate. Additional formants may be detected to derive additional information in the excitation signal.
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AT&T1
TL;DR: In this article, a spread-spectrum signal which conveys identifying information for an associated information signal is superimposed on the associated signal and transmitted therewith, which can be used for a variety of purposes within a communications network, such as facility and equipment selection, equipment disablement and bypass, setting communications parameters, and inhibiting communications upon fault detection.
Abstract: A spread-spectrum signal which conveys identifying information for an associated information signal is superimposed on the associated signal and transmitted therewith. Such identifying information distinguishes between voice and data information signals and between different types of data information signals. Such identification can be used for a variety of purposes within a communications network, such as facility and equipment selection, equipment disablement and bypass, setting communications parameters, e.g., speed, and inhibiting communications upon fault detection.
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IBM1
TL;DR: In this article, an intrusion barrier for protecting against mechanical or chemical intrusion into an electronic assembly, especially one containing volatile memory, is presented. But the barrier is not suitable for the use in the case of large-scale systems.
Abstract: The present invention provides an intrusion barrier for protecting against mechanical or chemical intrusion into an electronic assembly, especially one containing volatile memory. It includes a screen material surrounding the electronic assembly which screen material has formed thereon fine conductive lines in close proximity to each other. The lines are formed of conductive particles of material dispersed in a solidified matrix of a material which looses its mechanical integrity when removed from the screen. An electrical supply and signal detection circuit is provided which generates an output signal responsive to a given change in resistance of the conductive lines, such that if the resistance changes are a result of a mechanical or chemical attack, a signal is generated which can cause the erasure of the volatile memory. Also, preferably radiation detection and temperature sensing circuits are provided to cause erasure of the volatile memory responsive to detection of a given intensity of radiation or a temperature below a given value.
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10 Jul 1990
TL;DR: In this article, a control for a moisture sensing assembly, adapted for mounting on the inner surface of a vehicle window or windshield to control vehicle accessories such as windshield wipers, maximizes the window area being sensed in relationship to the size of the assembly and provides immunity to interference from environmental influences.
Abstract: A control for a moisture sensing assembly, adapted for mounting on the inner surface of a vehicle window or windshield to control vehicle accessories such as windshield wipers, maximizes the window area being sensed in relationship to the size of the assembly and provides immunity to interference from environmental influences. In the preferred embodiment, moisture on the outer window surface is detected by first and second moisture sensors each including infrared energy radiating diodes and radiant energy detectors which detect and process radiant energy to produce a moisture signal that is a function of the moisture on the window. A synchronizing circuit intermittently actuates the radiating diode for the two sensors individually and alternatingly at equally-spaced intervals. The synchronizing circuit also inhibits the radiant energy detectors from processing the radiant energy signal except when the corresponding radiating diodes are emitting energy in order to prevent interference from the other radiating diodes and environmental influences. The synchronizing circuit includes a pair of oscillators which include capacitors and coupling devices that coordinate the discharging of the capacitors in a manner which provides equal intervals between alternating output pulses from the oscillators.
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20 May 1990••
TL;DR: In this article, the authors used a first-order, finite-state, discrete-time Markov process to extract small, single channel ion currents from background noise, which can be used to detect signals that do not conform to a firstorder Markov model, but the method is less accurate when the background noise is not white.
Abstract: Techniques for extracting small, single channel ion currents from background noise are described and tested. It is assumed that single channel currents are generated by a first-order, finite-state, discrete-time, Markov process to which is added `white' background noise from the recording apparatus (electrode, amplifiers, etc.). Given the observations and the statistics of the background noise, the techniques described here yield a posteriori estimates of the most likely signal statistics, including the Markov model state transition probabilities, duration (open- and closed-time) probabilities, histograms, signal levels, and the most likely state sequence. Using variations of several algorithms previously developed for solving digital estimation problems, we have demonstrated that: (1) artificial, small, first-order, finite-state, Markov model signals embedded in simulated noise can be extracted with a high degree of accuracy, (2) processing can detect signals that do not conform to a first-order Markov model but the method is less accurate when the background noise is not white, and (3) the techniques can be used to extract from the baseline noise single channel currents in neuronal membranes. Some studies have been included to test the validity of assuming a first-order Markov model for biological signals. This method can be used to obtain directly from digitized data, channel characteristics such as amplitude distributions, transition matrices and open- and closed-time durations.
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26 Sep 1990
TL;DR: In this paper, the authors propose an inventory control system for a bar that automatically determines the weight of a plurality of articles (14), each of the articles having a surface portion (54) with a unique element thereon.
Abstract: Apparatus for automatically determining the weight of a plurality of articles (14), each of the articles (14) having a surface portion (54) with a unique element thereon, comprises a plurality of assemblies (22) and a computer (56). Each assembly (22) includes a surface (30) for supporting an article (14), a transducer (36) in operative contact with the supporting surface (30) for producing an output signal indicative of the weight of an article (14) placed on the supporting surface (30), and a sensor (48) in operative relationship with an article (14) on the supporting surface (30) for producing an output signal indicative of the unique element on the surface portion (54) of the article. A computer (56) receives the transducer output signals and the sensor output signals and, for each article (14) on the supporting surfaces (30), computes the weight of the article based on the transducer output signal and identifies the article (14) based on the sensor output signal. The apparatus is especially useful as an inventory control system for a bar.
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10 Oct 1990
TL;DR: In this article, a superluminescent light-emitting diode light source (SLD1-SLDn) is driven by a power driver (PD) supplied by a high frequency oscillator (HFO) with an oscillatory drive signal at a visually imperceptible but highly efficient operating frequency, the oscillatory driver signal preferably being a pulse signal of 1 to 5 KHz, to cause the light source to be illuminated and extinguished at the oscillator drive signal frequency, such that extinction of a light source is not visually perceptible.
Abstract: A device includes a flashing safety warning light in which a superluminescent light-emitting diode light source (SLD1-SLDn) is driven by power driver (PD) supplied by a high frequency oscillator (HFO) with an oscillatory drive signal at a visually imperceptible but highly efficient operating frequency, the oscillatory drive signal preferably being a pulse signal of 1 to 5 KHz, to cause the light source to be illuminated and extinguished at the oscillatory drive signal frequency, such that extinction of the light source is not visually perceptible. The oscillatory drive signal is in turn gated on and off in accordance with a gating signal from a low frequency oscillator (LFO) at a low, highly visually perceptible frequency in the range of 3 to 12 Hz with a pulse duty cycle of between 10 to 60 % in order to cause the light source to be visually perceived as flashing on and off at the gating signal frequency in an attention-attracting manner.
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NEC1
TL;DR: In this article, a speech coding method in which spectrum parameters representing a spectrum envelope and a pitch parameter representing a pitch are obtained from an input discrete speech signal is presented. And a frame interval is divided into subintervals in accordance with the pitch parameter.
Abstract: A speech coding method in which spectrum parameter representing a spectrum envelope and a pitch parameter representing a pitch are obtained from an input discrete speech signal. A frame interval is divided into subintervals in accordance with the pitch parameter. A sound source signal in one of the subintervals is obtained by obtaining a multipulse with respect to a difference signal obtained by performing prediction on the basis of a past sound source signal. Correction information for correcting at least one of the amplitude and the phase of the sound source signal are obtained and output in other pitch intervals in the frame.
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TL;DR: In this paper, a speech coding system which recursively executes a filter-applied "Toeplitz characteristic" by causing a drive signal (i.e., an excitation signal) to be converted into a "Toplitz matrix" when detecting a pitch period in which distortion of the input vector and the vector subsequent to the application of filter applied computation to the drive signal vector in the pitch forecast called either closed loop or compatible code book is minimized.
Abstract: This invention provides a novel speech coding system which recursively executes a filter-applied "Toeplitz characteristic" by causing a drive signal (i.e., an excitation signal) to be converted into a "Toeplitz matrix" when detecting a pitch period in which distortion of the input vector and the vector subsequent to the application of filter-applied computation to the drive signal vector in the pitch forecast called either "closed loop" or "compatible code book" is minimized. The vector quantization method substantially making up the speech coding system of the invention is characteristically used by the system.
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18 Oct 1990
TL;DR: In this paper, the authors proposed a zone-noned microcell system with sector scanning for cellular telephone systems, where each cell has at least one cell having a plurality of antenna sets (13, 15, 17, 18).
Abstract: A zoned microcell system (1) with sector scanning for cellular telephone systems has a plurality of contiguous cells, each having a different assigned set of transmission frequency channels, and handoff capability for maintaining communication from cell to cell. The system includes at least one cell (11) having a plurality of antenna sets (13, 15, 17). Each set is positioned at a respective sub-site (10, 16, 18), and configured so that propagation and reception of signals is limited to a transmission zone (13z, 15z, 17z) within the boundaries of, and which is less in area than the cell. A control device (79) monitors the strength of the signal received by each antenna set. Transmission, at each frequency channel, is confined to the antenna set having the strongest received signal thus limiting signal propagation to that transmission zone. In one embodiment, signal strength monitoring is provided at each sub-site, thus transmission is confined to a specific sub-set of antennas at the sub-site, and to a limited sector (115x, 115y, 115z) within the transmission zone.
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14 Feb 1990
TL;DR: In this article, a wrist worn heart rate monitor (100) senses a noisy biosignal with one sensor (104A) in contact with the user's finger and another sensor(104B) was placed on the wearer's wrist.
Abstract: A wrist worn heart rate monitor (100) senses a noisy biosignal with one sensor (104A) in contact with the user's finger and another sensor (104B) in contact with the user's wrist. The sensed signal is modified by a filter (112), analog to digital converter (116) and digital filter (264). A correlator (272) and QRS detector (286) are used to determine characteristics of a first segment of the modified signal. A match filter (300) and learned user reference (206) are used to match a second segment of the modified signal with the determined characteristics of the first segment to produce a processed signal. The QRS detector (286), an interval judge (292), and a momentum machine (202) determine the heart rate from the processed signal. A performance predictor (260) predicts how well the heart rate monitor (100) will perform with an individual user.
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07 Oct 1990TL;DR: In this paper, a low-cost position-sensing scheme using stator inductance measurement is presented, where an analog electronic technique can be applied to measure the inductance of a nonconducting phase by using a linear frequency modulated (FM) converter.
Abstract: Shaft position sensing is essential in switched reluctance motors (SRMs) in order to synchronize the phase excitation pulses to the rotor position. In order to implement closed loop torque control, current sensors are also unavoidable. These sensors can constitute a substantial portion of the total system cost and tend to reduce system reliability. A low-cost position-sensing scheme using stator inductance measurement is presented. An analog electronic technique can be applied to measure the inductance of a nonconducting phase by using a linear frequency modulated (FM) converter. The output of the FM converter is decoded to get the shaft position signal. The control functions and converter switching signals are processed in a low-cost microcontroller. The discrete current sensors for closed-loop operation have been eliminated by using MOS-gated power switches with integrated current sensing capability. The combination of the above two schemes resulted in a totally sensorless SR motor drive. >
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30 Oct 1990
TL;DR: In this article, a physician speaking commands that are received by a microphone (10) converts audio signals from the microphone into word signals and compares each word signal with a list of previously authorized command words.
Abstract: During surgery, a physician speaks commands that are received by a microphone (10). A speech processor (12) converts audio signals from the microphone into word signals. A command interpreter (14) compares each word signal with a list of previously authorized command words. When the word signal corresponds to one of the preselected command words, a corresponding command signal is generated and sent to a volume imager (18), a video recorder (20), a hard copy, printer (28), or other system component. The volume imager generates an image representation signal indicative of a portion of image data stored therein which is displayed on a video monitor (B) or recorded on the video recorder.
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04 Apr 1990TL;DR: In this article, a cardiac pacer apparatus includes a pacer can which functions as a fourth electrode and has a plastic top wherein the third electrode is located, which acts in cooperation with the first electrode to form a pair of sensing electrodes and is further coupled to a sense amplifier for receiving an amplifying modulated electrical signals developed across the sensing electrode pair.
Abstract: An endocardial lead having first and second spaced apart electrodes resides in a patient's heart. The first electrode is a sensing electrode and the second electrode is a carrier signal driving electrode. The lead has a conductor coupling a source of alternating current carrier signals of a predetermined frequency to the second electrode. A third electrode is in electrical contact with body tissues. A cardiac pacer apparatus includes a pacer can which functions as a fourth electrode and has a plastic top wherein the third electrode is located. Said third electrode acts in cooperation with the first electrode to form a pair of sensing electrodes. The sensing electrode pair is further coupled to a sense amplifier for receiving an amplifying modulated electrical signals developed across the sensing electrode pair. A demodulator and filters circuit for demodulating the modulated carrier signal and recovering the modulating signal therefrom is connected to the output of the sense amplifier. The modulating signal is proportional to instantaneous stroke volume of the patient's heart and the demodulator and filters circuit develops a control signal therefrom called a stroke volume signal. The control signal is applied to the pulse generator so as to control the rate of stimulating pulses.
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01 Mar 1990
TL;DR: In this paper, a variable gain amplifier (14) is used for amplifying a voice input signal (12) at a gain dependent on a variable control voltage (32), and the comparator (24) is set to a high threshold state by the threshold reset timer (26).
Abstract: A voice signal compression system (10) includes a variable gain amplifier (14) for amplifying a voice input signal (12) at a gain dependent on a variable control voltage (32). A driver (18) receives the amplified input signal and supplies a power-boosted output signal (20) to an acoustic output transducer, a peak detecting comparator (24), and to a thresold reset timer (26). The comparator (24) produces a digital output that triggers an attack/decay timer (30) which produces the control voltage (32). The comparator (24) initially is set to a high threshold state by the threshold reset timer (26). As the levels and peaks of the input signal (12) increase, the comparator (24) begins to trigger digital pulses to the attack/decay timer (30), and the threshold reset timer (26) begins measuring the duration of the signal which exceeds the threshold of the comparator (24). If the level of the power-boosted output signal (20) exceeds the threshold of the comparator (24) for a preselected time, then the compression threshold of the comparator (24) is switched to a lower level. The threshold remains low until the continuous signal is removed whereupon the comparator (24) is reset to its higher threshold.
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TL;DR: In this article, it is shown how a partial discharge (PD) within a test sample generates a signal that can be measured outside the apparatus under test, and the fundamentals of how the phenomenon generates a current in the external circuit are explained.
Abstract: It is shown how a partial discharge (PD) within a test sample generates a signal that can be measured outside the apparatus under test. Because the transfer function between the phenomenon within the apparatus under test and the signal that can be measured can vary widely, measured partial-discharge magnitudes rarely have absolute meaning and are often referred to as effective partial-discharge magnitude to acknowledge this uncertainty. The most common sources of PD are floating components, corona, and voids. Each of these is considered in turn, and the fundamentals of how the phenomenon generates a current in the external circuit are explained. >
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20 Feb 1990TL;DR: In this paper, an improved telemetry system for telemetering digital data from an implantable tissue stimulator such as a heart pacemaker is presented, where a carrier signal is modulated in accordance with either or both of stored digital data and a digitized electrocardiogram signal.
Abstract: An improved telemetry system for telemetering digital data from an implantable tissue stimulator such as a heart pacemaker. A carrier signal is pulse modulated in accordance with either or both of stored digital data and a digitized electrocardiogram signal, for coupling onto an electrical lead connected directly to the heart. This arrangement facilitates the transmission of substantially higher data rates than previously could be achieved.