Showing papers on "Signal published in 1989"

Discrete-Time Signal Processing

Abstract: For senior/graduate-level courses in Discrete-Time Signal Processing. THE definitive, authoritative text on DSP -- ideal for those with an introductory-level knowledge of signals and systems. Written by prominent, DSP pioneers, it provides thorough treatment of the fundamental theorems and properties of discrete-time linear systems, filtering, sampling, and discrete-time Fourier Analysis. By focusing on the general and universal concepts in discrete-time signal processing, it remains vital and relevant to the new challenges arising in the field --without limiting itself to specific technologies with relatively short life spans.

Vehicle location system

Abstract: A system for determining a location of a selected vehicle from which an alarm signal is generated which includes a fixed array of cellular sites each site having a wireless signal detecting and generating units each of which is capable of receiving an input alarm signal having a signal strength which is a function of the distance between the position of the vehicle generating the alarm signal and the position of each of the wireless signal detecting units. Each unit also is capable of transmitting an output signal which is a function of the strength of the input alarm signal. The system also includes a main wireless signal detecting apparatus for receiving an output signal from each of the wireless signal detecting and generating units and a control monitoring unit which is coupled to the main wireless signal detecting apparatus, for receiving output signals there from, each of the output signals being a function of the strength of the received input alarm signal, for determining the approximate location of the selected vehicle from which the alarm signal is generated.

Random neural networks with negative and positive signals and product form solution

Abstract: We introduce a new class of random neural networks in which signals are either negative or positive. A positive signal arriving at a neuron increases its total signal count or potential by one; a negative signal reduces it by one if the potential is positive, and has no effect if it is zero. When its potential is positive, a neuron fires, sending positive or negative signals at random intervals to neurons or to the outside. Positive signals represent excitatory signals and negative signals represent inhibition. We show that this model, with exponential signal emission intervals, Poisson external signal arrivals, and Markovian signal movements between neurons, has a product form leading to simple analytical expressions for the system state.

Shift assisting device

Abstract: A shift assisting mechanism for a marine outboard transmission that includes a sensing device comprised of a pair of relatively movable levers with pressure responsive switches being effective to transmit movement between the levers and provide a shift controlling signal when the resistance to movement exceeds a predetermined value.

Microprocessor controlled rate-responsive pacemaker having automatic rate response threshold adjustment

Abstract: A rate-responsive pacemaker which includes a conventional programmable pulse generator, a physiological sensor, and a processor is disclosed which generates heart stimulation pulses on demand, or as otherwise programmed, as controlled by a rate control signal which is derived from the physiological sensor. The physiological sensor generates a raw signal which varies as a function of some physiological parameter, such as activity level to provide some indication of whether the heart rate should increase or decrease, and hence whether the pacemaker should change the rate at which pacing pulses are provided. The processor converts the raw signal to the sensor-indicated rate signal in accordance with a selectable transfer relationship which defines the sensor-indicated rate signal as a function of a set of discrete sensor level index signals. The sensor-indicated rate signal remains at a minimum value or base rate for all sensor level index signals below a prescribed rate response threshold, with this rate response threshold being set automatically by the processor as a function of a running average of the sensor level index signals monitored over a prescribed time period.

Microprocessor controlled arthroscopic surgical system

Abstract: An apparatus for controlling the speed of a plurality of DC motors, comprises a device for supplying voltage to one of the plurality of DC motors, first selector for selecting one of the DC motors to be connected to the device for supplying voltage, second selector for selecting a desired speed for the selected DC motor, a device for producing a feedback signal representative of an electrical current drawn by the selected DC motor and a controller for: (i) producing a reference voltage in response to the first and second selectors (ii) producing a load voltage in response to the feedback signal and (iii) outputting a control signal which is the sum of the reference voltage and the load voltage to the device for supplying voltage so that the selected DC motor is operated at the desired speed.

Mobile radio data communication system and method

Abstract: In an exemplary embodiment, a test signal is sent by a base station at a suitable point in a communi­ications protocol. According to the evaluation of the test signal transmission, a relatively high data rate or a lower more conservative data rate is selected by a mobile unit for the transmission of a relatively lengthy data message. The test signal can be associated with a query from a mobile unit having a message to send, or with a contention polling message from the base. Such test signal can be transmitted at the lower data rate where its transmission characteristics (e.g. signal strength, jitter or quality of transmission of known information) can be used to predict probable feasibility of transmission at the higher data rate, but most preferably the test signal is part of a high data rate contention poll which may alternate with a low data rate contention poll.

Embedment of data in a video signal

Abstract: Data is embedded in a video signal by adding a low level wavefrom to the video signal, the low level wave form having a level below the noise level of the video signal and corresponding to the data. To detect the data embedded in the video signal the video signal is correlated with the low level waveform corresponding to the data to produce a correlation coefficient. A high correlation coefficient indicates the presence of a low level waveform which is converted into the data. The low level waveform extends over many video lines such that it does not occur at or near the same location within a video frame for many video frames to avoid fixed-pattern noise anomalies that may be detected by a viewer of the television picture.

Magnetic resonance imaging system

Abstract: A magnetic resonance imaging system includes a magnetic field applying section for applying a static field, gradient field pulses, and an RF field to an object to be examined, a signal detecting section, including a homogeneous coil and a plurality of surface coils arranged to surround a desired region of the object, for detecting magnetic resonance signals from the object through the homogeneous coil and the surface coils, and an image data processing section for obtaining an image of the desired region by synthesizing image data based on the magnetic resonance signals respectively detected by the surface coils upon weighting/adding processing. The system uses differential surface coils as the surface coils. A magnetic resonance signal is detected through the homogeneous coil within the same time interval in which magnetic resonance signals are detected through the surface coils. Weighting functions for weighting/adding processing of image data are determined on the basis of these magnetic resonance signals.

System for evaluation and rewarding of responses and predictions

Abstract: A system and method for evaluating responses to broadcast programs, such as television programs, includes an instructional signal modulated onto a signal transmitted concurrently with the television program, or time-multiplexed with a television. At each of a plurality of remote receiving stations, one or more members of a remote audience has the opportunity to respond to a situation presented in the television program by entering a response on a keyboard. The system includes, at each remote receiving station, a memory responsive to the instructional signal for storing acceptable responses, and a comparison circuit for comparing responses entered at the keyboard with those stored in the memory. Also provided is electronic circuitry for scoring the responses in accordance with commands from the instructional signal, and a recording device for providing a permanent record of the audience score at each of the remote receiving stations. Scoring is performed at differing levels of difficulty, set by a host or by a contestant, with credit being given also for the length of time required for response. The mode of response includes the use of a key word or phrase. Alternatively, the program may be presented by a prerecorded message accessible by telephone from a remote station with regulation from a central station.

Multiple chemically modulated capacitance determination

Abstract: Apparatus and methods are provided for multiple detection of analytes employing semiconductor capacitance as the signal modulated by the analyte. A plurality of semiconductor capacitors are organized for detection (at individual sites) of changes in capacitance which are related to changes in a fluid medium, where the change can be related to the presence of an analyte. Circuitry is designed to substantially maximize sensitivity.

Emergency transmitter system

Abstract: An emergency transmitter system is disclosed for enhancing the personal security of individuals within a predetermined geographic area such as a campus, shopping mall or stadium. A plurality of fixed transceivers are located at selected locations within the predetermined geographic area, preferably in a substantially equidistant pattern throughout the area. In a preferred embodiment of the present invention, each fixed transceiver is preferably located in conjunction with a street light in an elevated location. A battery powered low power portable transmitter is then issued to selected individuals, each transmitter including circuitry for transmitting a coded signal associated with a particular individual. In the event of an emergency situation, the portable transmitter is activated, utilizing an irrevocable manual activation switch, and the coded signal is transmitted utilizing the low power radio frequency signal. Reception of the coded signal at one or more fixed transceivers will cause those transceivers to retransmit that coded signal along with a second coded signal indicative of the locations of the fixed transceivers. Reception of this signal at a central receiver will result in a display indicating the particular individual and the geographic location as determined by the locations of the fixed transceivers, thus allowing security personnel to rapidly respond to an emergency situation while discouraging prank alarms.

High frequency electrosurgical apparatus for thermal coagulation of biologic tissues

Abstract: A high frequency surgical apparatus for the thermal coagulation of biologic tissues is described, in which for monitoring the fluctuations in amplitude of the high frequency current during each coagulation process a current monitor (25) is provided, which by means of a current-to-voltage coverter generates an electrical voltage proportional to the amplitude fluctuations of the high frequency current, from which voltage, by means of a first detector, a first direct voltage proportional to the amplitude fluctuations is formed and, by means of a second detector acting as a peak value detector, a second direct voltage is formed that rises in proportion to the amplitude of the high frequency current. The first direct voltage (Ua) and the second direct voltage (kUb), which is divided downward by an adjustable factor by means of a voltage divider, are supplied to a voltage comparator, the output signal of which sets a bistable circuit as soon as the first direct voltage (Ua) becomes lower than the downwardly divided second direct voltage (kUb). The output signal of the bistable circuit switches the high frequency current off until the high frequency current is switched back on again by actuation of a manual switch and/or by means of an automatic switch. Instead of or in addition to this current monitor (25), and electric arc monitor (26) for monitoring the generation of anharmonic frequencies of the base frequency of the frequency generator can be connected to the output of the surgical apparatus, the arc monitor including a filter which passes at least one of the anharmonic frequencies, generated by the electric arc, of the base frequency of the high frequency generator. The output signal of the filter is supplied to a voltage comparator, the output signal of which resets a bistable circuit such that its output signal switches off the high frequency current.

Signal identification system

Abstract: A signal identification system, suitable for producing an identification code on a sound track recording is described. The system includes an encoder 209 effective to eliminate a variable sequence of frequency bands from an audio signal and insert a sequence of code signals into the frequency bands. As the sequence of frequency bands varies throughout the sound track recording, the presence of the code is difficult to detect.

A device for chronic measurement of internal body pressure

Abstract: Measurement of a physiological pressure is accomplished by placement of a pressure transmitting catheter (20) within a blood vessel or other structure within which pressure is to be measured. The catheter (20) is blood-compatible, capable of withstanding handling during distribution and implantation, and provides adequate pressure transmission frequency response in a variety of applications. The catheter (20), which includes a hollow tube filled with a low viscosity fluid (29) and having a plug (30) of a gel-like material at its distal end (22), transmits the pressure signal to a solid-state transducer (16) which is typically connected to amplifying electronics and an implantable radio-transmitter (18) capable of relaying the pressure information from within the body to a radio receiver external to the body.

Pressure mapping system with capacitive measuring pad

Abstract: A pressure distribution measuring system includes a pad of insulating material disposed between two linear arrays of electrodes to form a matrix of capacitive nodes. A capacitance related output signal that is obtained from a node of interest is used as a feedback signal and applied to other capacitors that are connected in common with the node of interest. The feedback signal inhibits the flow of current through these commonly connected capacitors, and thereby isolates the measured signal from any changes in the capacitance of these other capacitors. The pad includes a cental array of linear electrodes sandwiched between two layers of dielectric foam material. Two outer, aligned linear electrode arrays, oriented perpendicular to the central array, are respectively disposed on the outside surfaces of the dielectric layers. In a preferred form, alternating electrodes in each outer array are located on opposite sides of a support substrate. This construction increases the amplitude of the measured signal, isolates the measured signal from the ambient environment, and reduces the susceptibility of the measuring process to errors caused by wrinkling of the pad as a person lies on it, or the like.

Adaptive Detection and Parameter Estimation for Multidimensional Signal Models

Abstract: : The problem of target detection and signal parameter estimation in a background of unknown interference is studied, using a multidimensional generalization of the signal models usually employed for radar, sonar, and similar applications. The required techniques of multivariate statistical analysis are developed and extensively used throughout the study, and the necessary mathematical background is provided in Appendices. Target detection performance is shown to be governed by a form of the Wilks' Lambda statistic, and a new method for its numerical evaluation is given which applies to the probability of false alarm of the detector. Signal parameter estimation is shown to be directly related to known techniques of adaptive nulling, and several new results relevant to adaptive nulling performance are obtained.

Continuously adaptive moisture sensor system for wiper control

Abstract: An adaptive moisture sensor system includes a moisture sensor unit having a moisture sensor, which produces a moisture signal, a reference signal generating circuit and a comparator circuit for comparing the moisture signal with the reference signal and for producing an indication to the vehicle's wiper control of the relationship between the signals. The reference signal generating circuit indicates a fast positive signal processing circuit for rapidly processing changes in the moisture signal representing decreasing moisture and a slow signal processing circuit to process changes of the moisture signal in both directions at a slow rate. The fast positive signal processing circuit is only enabled during rain conditions due to a contaminant film on the sensed window. The reference signal generating circuit further includes a fast negative signal processing circuit which responds to a stable moisture signal occuring during rain conditions by rapidly offsetting the reference signal to discontinue wiper operation. Multiple sensing assemblies, each including a sensor, a reference signal generating circuit and a comparator, are combined with a master control unit, which responds to any sensing assembly indicating a rain condition, in order to switch all sensing assemblies to a rain mode.

Paging accessory for portable information/computing devices

Abstract: A paging accessory (10) for portable computing devices (12) such as calculators, electronic notebooks, calendars or the like. The paging accessory (10) includes a board (14) on which are mounted a receiver (32) for receiving page signals and a microprocessor (34) for identifying and decoding a page signal intended for the accessory (10). The board (14) includes connectors (16) for inserting the accessory (10) into a port (15) of a portable computing device (12). Alternatively, receiver (32) may be incorporated directly into a device (12). The device (12) is programmed to compare information in its memory. For example, it can compare a received phone number against a list of phone numbers to identify the person to be called in response to the page.

Television local wireless transmission and control

Abstract: A wireless local television transmission system with related methods, apparatus, and components. There is a source of a video signal to be viewed at a remote location such as a TV camera, cable select box, antenna, or VCR. An up converter is connected to the source for shifting the video signal to a frequency above the normal television bands. A transmitter is connected to the up converter for transmitting the video signal at the shifted frequency. A receiver is disposed at the remote location for receiving the transmitted video signal. A down converter is connected to the receiver for shifting the video signal back down to a frequency within the normal television bands and identified with a known channel. Finally, conventional television set functions are connected to the down converter for processing and displaying the video signal on the known channel. The preferred up conversion shifts the video signal to a frequency in the band of 902-928 MHz and frequency modulates the video signal on a carrier within that band. Provision is also provided for the wireless transmission of control signals provided by a conventional infra red controller/transmitter so that the controller/transmitter can be used at the location of either the VCR or the television set. The preferred embodiment employs a single controller/transmitter for both VCR and television control. An improved cable select box is disclosed employing two tuners and wireless signal transmission. A wireless video camera/recorder system is also disclosed. The disclosure also includes a universal controller/transmitter transmitting IR and RF signals simultaneously as well as a directional antenna to be employed with receiving equipment to reduce interference.

Scanning near-field acoustic microscopy

Abstract: Scanning near-field acoustic microscopy (SNAM) is a new method for imaging the topography of nonconducting surfaces at a potential lateral resolution in the sub-micron range. The basic element of this method is a distance sensor consisting of a sharply pointed vibrating tip, which is part of a high-Q quartz resonator driven at its resonance frequency. The decrease of the resonance frequency or of the amplitude of vibration when an object comes into the proximity of the tip serves as the important signal. The dependence of this signal on pressure and composition of the coupling gas shows that the hydrodynamic forces in the gas are responsible for the coupling between object and tip. The sensor is incorporated into a scanning device. Well-resolved line scans of a grating of 8 μm periodicity, a lateral resolution of 3 μm and a vertical resolution of 5nm have been achieved in our first experiments.

Transcutaneous electrical nerve stimulation (TENS) device

Abstract: An improved transcutaneous electrical nerve stimulator (TENS) involving a microcurrent (typically 25 to 900 microamps) monophase D.C. carrier signal (typically 10,000 to 19,000 Hz, preferably 15,000 Hz) that is modulated on and off in time (typically at 0.3 Hz up to 10,000 Hz, preferably 9.125 Hz followed by 292 Hz) and further inverted about every second by reversing the polarity of the signal at the electrodes. Such a device has been found to be useful in alleviating pain very rapidly.

Alarm system utilizing wireless communication path

Abstract: An alarm system for a protected premises includes an alarm sensor for generating an alarm signal in the event of an alarm condition. A cellular-type radio/telephone transceiver is located at the protected premises and includes circuitry for generating and transmitting a unique identification number of the transceiver and a send signal for wireless communication with a cellular site. Structure is provided for connecting the alarm signal line to the cellular-type radio/transceiver such that upon receipt of the alarm signal, the cellular-type radio/transceiver will transmit the unique identification number and the send signal to the cellular site with no transmission of the telephone number of an alarm monitoring station to thereby enable the cellular site to transmit the alarm condition to the alarm monitoring station.

Smart sensor system for diagnostic monitoring

Abstract: The present invention is a component monitoring system which includes all sensor and plant component monitoring at distributed plant locations close to the sensors which are the source of the signals to be analyzed. Minimally preconditioned analog sensor signals are multiplexed and further conditioned by a sensor signal preprocessor that adjusts the gain and filters the sensor signals before being applied to an analog-to-digital converter controlled by a data acquisition computer. The analog sensor signals are converted into digital samples and stored in a data memory of a digital signal processor using a direct memory access technique. The data acquisition computer also controls the selection of sensors, gain, etc., based on commands from a controller. The digital signal processor, once sufficient sensor data has been collected, performs appropriate processing using known digital signal processing techniques. This processed data is then sent to the controller for analysis to determine plant component condition. The analysis and processing routines can be changed by downloading a new routine from the controller. Once a sensor signal is processed, the controller selects the next sensor by transmitting an appropriate command to the data acquisition computer.

Spread spectrum communication system

Abstract: A transmitter of a spread spectrum communication system uses a first carrier, a second carrier, a third carrier, a first spread code, and a second spread code. The third carrier is generated by shifting the phase of the first carrier. The second spread code is generated by delaying the first spread code. The first carrier is modulated with an information signal to generate a primary modulation signal. A composite spread spectrum signal is generated by combining and mixing the primary modulation signal, the second carrier, the third carrier, the first spread code, and the second spread code. In a receiver of the system, a separation filter separates the composite spread spectrum signal into a first component and a second component related to the frequency of the first carrier and the frequency of the second carrier respectively. A signal corresponding to the primary modulation signal is demodulated by processing the first and second components of the composite spread spectrum signal. A fourth carrier synchronous with the demodulated signal is derived by processing the first and second components of the composite spread spectrum signal. The information signal is detected by mixing the demodulated signal and the fourth carrier.

A receiver-compatible enhanced definition television system

Abstract: A television encoder for generating a receiver-compatible signal from a production video signal containing enhancement information which cannot be displayed on a standard receiver, the receiver-compatible signal being compatible with the standard receiver, the encoder including a filter bank for dividing the video signal into at least two groups of spatial frequency components including a first group and a second group, the first group containing members which when combined together form a standard video signal which is displayed by the standard receiver and the second group containing the enhancement information; a quantizer for quantizing at least one member of the first group; a combiner for adding at least one member of the second group to a quantized member of the first group to produce a modified first group; and a synthesizer for combining the members of the modified first group to generate the receiver-compatible signal.

Electromagnetic method and apparatus for healing living tissue

Abstract: A non-invasive, portable electromagnetic therapeutic method and apparatus for promoting the healing of damaged or diseased living tissue including fractured bone and in particular nonunion or delayed union bone fractures are described. The method and apparatus involve generating a signal having a series of substantially symmetric voltage cycles of bursted pulses having narrow pulse widths on the order of 0.5 to 20 microseconds and converting the signal into an electromagnetic field which extends into an area for desired tissue healing. The portable noninvasive apparatus can be readily worn or carried by a patient and is capable of generating an energy-efficient symmetrical signal coacting with a coil for transducing the signal into electromagnetic pulses.

Circuit for driving ultrasonic transducer

Abstract: Circuit for use in a surgical operation including a phase lock loop having a voltage controlled oscillator, and a phase comparator for comparing a phase of a voltage of a driving signal and a phase of a signal representing the vibration phase of the ultrasonic transducer to derive a phase difference therebetween which is applied to the voltage controlled oscillator as a frequency control voltage such that the driving signal is phase-locked with a resonance frequency of the ultrasonic transducer, the improvement being characterized in that during a start period, a reference signal having a frequency which is increased monotonously is applied to the phase comparator such that the frequency of the driving signal is increased until the driving signal is phase-locked with the vibration phase of the ultrasonic transducer vibrating at the resonance frequency. After the phase-lock condition has been attained, the signal representing the vibration phase of the ultrasonic transducer is applied to the phase comparator instead of the reference signal.