Showing papers on "Signal published in 1993"

Network controller for cable television delivery systems

Abstract: A novel network controller for use with a digital cable headend capable of monitoring and controlling set top terminals in a television program delivery system is described. The invention relates to methods and apparatus for a network controller that manages a configuration of set top terminals in a program delivery system. The invention is particularly useful in program delivery systems with hundreds of channels of programming, a menu driven program selection system, and a program control information signal that carries data and identifies available program choices. Specifically, the invention modifies a program control information signal at the cable headend before the modified signal is transmitted to each set top terminal. This signal is used with polling methods to receive upstream data from the set top terminals. The invention initiates such upstream data retrieval, gathers all data received and compiles viewer demographics information and programs watched information. The invention processes this data and information to generate packages of advertisements, as well as account and billing reports, targeted towards each set top terminal. The invention uses upstream data reception hardware, databases and processing hardware and software to accomplish these functions.

Energy separation in signal modulations with application to speech analysis

Abstract: An efficient solution to the fundamental problem of estimating the time-varying amplitude envelope and instantaneous frequency of a real-valued signal that has both an AM and FM structure is provided. Nonlinear combinations of instantaneous signal outputs from the energy operator are used to separate its output energy product into its AM and FM components. The theoretical analysis is done first for continuous-time signals. Then several efficient algorithms are developed and compared for estimating the amplitude envelope and instantaneous frequency of discrete-time AM-FM signals. These energy separation algorithms are used to search for modulations in speech resonances, which are modeled using AM-FM signals to account for time-varying amplitude envelopes and instantaneous frequencies. The experimental results provide evidence that bandpass-filtered speech signals around speech formants contain amplitude and frequency modulations within a pitch period. >

Ablation catheter positioning system

Abstract: A multi-electrode cardiac catheter (10) has pairs of electrodes (13) connected to sensing circuitry (31, 32, 40) to produce a differential signal. The sensing output is sharply defined and self normalizing. Preferably, a catheter ablation tip electrode (12) is an electrode of one pair, and the differential signal becomes non-zero when the tip contacts surrounding tissue. The shape of the differential signal provides information on the degree of electrode contact, as well as on the amount of locally-sensed tissue impedance change. The signal may be used as a trigger enable signal for a cardiac ablation catheter (10), and the applied level of RF power may be controlled based on the indicated degree of electrode contact and value of tissue impedance.

Subcutaneous multi-electrode sensing system, method and pacer

Abstract: A method and apparatus for providing an enhanced capability of detecting and gathering electrical cardiac signals via an array of relatively closely spaced subcutaneous electrodes (located on the body of an implanted device) which may be employed with suitable switching circuits, signal processors, and memory to process the electrical cardiac signals between any selected pair or pairs of the electrode array in order to provide a leadless, orientation insensitive means for receiving the electrical signal from the heart. This far-field EGM may be used to provide storage and analysis of arrhythmic events and to provide control signals for the delivery of various therapies including pacing, cardioversion and defibrillation therapies as well as the delivery of antiarrhythmic drugs, and, in the pacing context, to effect capture detection and automatic stimulation threshold adaption, recording of PMT episodes, measurement of refractory periods in order to set timing windows for antitachy pacing therapies, and as a control signal for use in adjusting pacing rate to physiologic demand.

Automatic bipolar control for an electrosurgical generator

Abstract: An automatic circuit measures electrosurgical generator output and controls in accord with impedance between activated movable bipolar electrodes able to contact tissue. Voltage monitor in parallel and current monitor in series with the electrodes measure instantaneous variations and generate proportional signals. First and second calculators receive the signals and find respectively, by dividing the voltage by current, short circuit impedances and impedances other than short circuit impedances between the electrodes. First and second comparators receive the respective outputs from the first and second calculators and assess them against respective first and second references providing signs of short conditions and assessments of changes in impedance between the electrodes. A logic analyzer receives the signs and assessments and evaluates them to permit the instantaneous starting, operating or stopping of the electrosurgical generator. The electrodes include an instrument and a set of cables with a preselected combined impedance so the maximum instantaneous impedance between the electrodes is less than the preselected combined impedance. The second reference is user adjustable. Switches, associated with each of the voltage monitor and the current monitor, choose the gain applied to the proportional signals respectively therefrom. First and second calculator gain changers receive the signals for setting the range across which those respective signals are used. Methods have steps of monitoring voltage and current, generating signals, dividing the voltage signal by current signal to find short circuit impedance between the electrodes and the instantaneous changes in impedance for other than the short circuit impedance, assessing those findings against references and permitting the starting, operating, or stopping of the electrosurgical generator.

Automatic rearview mirror system using a photosensor array

Abstract: A system apparatus, structure and method for controlling a plurality of variable reflectance mirrors (or mirror segments), including a rearview mirror and side view mirrors, which change their reflectance level in response to a plurality of drive voltages applied thereto, for an automotive vehicle. The system includes a light sensing device and a control circuit formed as a single VLSI CMOS circuit. The light sensing device comprises a photosensor array having a field of view encompassing a rear window area and at least a portion of at least one side window area of the vehicle. The logic and control circuit determines a background light signal from photosensor element signals generated by the photosensor elements in the photosensor array indicative of light levels incident on the photosensor elements. The circuit also determines a peak light signal in three different zones or sub-arrays of the photosensor array. The zones or sub-arrays may correspond to three mirrors or mirror segments. The peak light signals in each of the zones and a common background light signal are used to determine independent and separate control signals, which are then output to separate mirror drive circuits for independently controlling the reflectance level of the rearview mirror and the left and right side view mirrors, or alternatively the segments of a mirror.

The pathway to signal achievement

Abstract: There has been a deluge of reports, in this journal and elsewhere, dealing with the subject of signal transduction and the Ras protein. Why all the fuss? The following is a News and Views article with a difference - an explanation for those not close to events, and a celebration of an achievement in biomedical research.

Laser Doppler perfusion imaging by dynamic light scattering

Abstract: A laser Doppler perfusion imaging technique based on dynamic light scattering in tissue is reported. When a laser beam sequentially scans the tissue (maximal area approximately 12 cm*12 cm), moving blood cells generate Doppler components in the backscattered light. A fraction of this light is detected by a remote photodiode and converted into an electrical signal. In the signal processor, a signal proportional to the tissue perfusion at each measurement point is calculated and stored. When the scanning procedure is completed, the system generates a color-coded perfusion image on a monitor. A perfusion image is typically built up of data from 4096 measurement sites, recorded during a time period of 4 min. This image has a spatial resolution of about 2 mm. A theory for the system inherent amplification factor dependence on the distance between individual measurement points and detector is proposed and correction measures are presented. Performance results for the laser Doppler perfusion imager obtained with a flow simulator are presented. The advantages of the method are discussed. >

Vehicle tracking system

Abstract: A vehicle tracking system makes use of a conventional cellular telephone network including a plurality of fixed cellular transmitter sites each covering a predetermined area. The system includes a plurality of cellular signal processing units for installation at hidden locations in vehicles to be monitored. Each unit is connected to one or more different sensors in the vehicle, at least one of the sensors being a break-in detector for detecting tempering with the vehicle, and to a cellular antenna, and includes a controller for monitoring the sensor outputs and initiating an emergency message transmission to a remote monitoring station in the event of actuation of a sensor. The car processing unit monitors site identifying signals and signal strengths of transmissions from adjacent cellular transmitter sites in an emergency, and the emergency message includes vehicle identifying information, cell site identifying information, and signal strength information which will be dependent on distance from the cell site. The monitoring station includes a computer for determining and displaying an approximate vehicle location from the incoming cell site identifying and signal strength information.

Display for automatic rearview mirror

Abstract: A rearview mirror system for a vehicle having a reflective element with a reflective surface and a variable light transmission element includes an optical display device behind the reflective element in order to produce a visual display to the driver. A control is provided having a light sensor that senses light conditions in the vicinity of the vehicle and produces a continuously variable light signal indicative of such sensed light conditions. The control further includes a drive circuit that is responsive to the light signal in order to supply a drive signal to the reflective element and thereby establish the light transmission level of the light transmission element. The control further includes an intensity control circuit that varies the intensity of the optical display as a function of the value of the sensed light in the vicinity of the vehicle in order to accommodate physiological changes in the driver's eyes. The intensity control circuit further varies the intensity of the optical display device as a function of the drive signal supplied to the reflective element in order to compensate for reduced light transmission levels of the light transmission element. The intensity control circuit sums values of the light signal and the drive signal and processes the sum to a pulse-width modulated signal using a non-linear processor. The intensity control also provides a substantially constant high intensity of the optical display device for all values of sensed light above a predetermined high light level and for all values of sensed light below a predetermined low light level.

Method and apparatus for encoding/decoding broadcast or recorded segments and monitoring audience exposure thereto

Abstract: Methods and apparatus for encoding and decoding information in broadcast or recorded segment signals are described. In certain embodiment, an audience monitoring system encodes identification information x(w) in the audio signal portion of a broadcast or recorded segment using spread spectrum encoding (100). A personal monitoring device (200) receives an acoustically reproduced version of the broadcast or recorded signal via a microphone (230), decodes the identification information from the audio signal portion despite significant ambient noise and stores (260) this information, automatically providing a diary for the audience member which is later uploaded to a centralized facility. A separate monitoring device (700) decodes additional information from the broadcast signal, which is matched with the audience diary information at the central facility. This monitor (700) may simultaneously send data to the centralized facility using a dial-up telephone line, and receive data from the centralized facility through a signal encoded using a spread spectrum technique and modulated with a broadcast signal from a third-party.

Detection of multiple articles

Abstract: An identification system comprises an interrogator and a plurality of transponders. The interrogator includes a transmitter which transmits at least two independent interrogation signals to the transponders, and a receiver for receiving response signals from the transponders. The interrogator also includes processor means for identifying the transponders from data in the received response signals. Each transponder comprises receiving means, a code generator, and transmitter means connected to the code generator. On receipt of at least one of the transmitted interrogation signals the transponder transmits a response signal containing data which identifies it. The interrogation signals may be transmitted continuously or intermittently. In a preferred embodiment, the interrogation signals are relatively narrow bandwidth signals at different frequencies. The receiving means of each transponder has a relatively broad reception bandwidth so that the transponder is responsive to one or more of the interrogation signals.

Ultramicroelectrodes in Electrochemistry

Abstract: In the 1950s and 1960s fundamental developments in electrochemical methods included voltammetry and low signal techniques. A generation later, the discovery of the unusual properties of ultramicroelectrodes has opened new possibilities of analyzing electrode processes. The changes in mass transport conditions bring about extremely high current densities at ultramicroelectrodes, whereas the currents themselves become very small. This little-noticed phenomenon allows for many electroanalytical applications that are not possible with conventional electrodes, especially experiments in solutions with very low electrolyte concentrations, in nonpolar solvents, in solids, and even in gases. In addition, two factors— changes in the experimental time scale at low scan rates because of the size of the electrode, and insignificant iR effects at very high scan rates—make it possible to study very fast homogeneous and heterogeneous electrode processes.

Higher-order spectral analysis

Abstract: Absltacl The purpose of this keynote lecture of the Signal Analysis Track is U) present the motivation behind he use of higher-order spectra (HOS) in signal processing as well as the definitions, properties, and biomedica1 signal processing applications of higher-order spectra. This lecture will also emphasize the state of science of the higher-order spectra field, especially as it applies to non-stadonary signal analysis.

Identification of vascular structures as a major source of signal contrast in high resolution 2D and 3D functional activation imaging of the motor cortex at l.5T preliminary results

Abstract: We have measured the T2* signal response associated with cortical activation due to finger motion at 1.5 Tesla. Both thin slice 2D and 3D images show signal intensity changes which vary from 2% to 32% depending on volunteer, echo time, slice thickness, and in-plane resolution. The largest signal change occurred for the thinnest slices and highest resolution (2 mm3). This is consistent with reducing partial volume effects and a simple difference in phase between the intravascular signal and surrounding parenchyma. No inflow enhancement was seen on the 2D or 3D scans, confirming the nature of the signal difference for this approach was due to local field in-homogeneity effects. Using 3D imaging, multiple effects can be seen simultaneously. With a 3D MRA method, it was possible to locate the vessel that was the source of the T2* behavior; it was in each case a vein on the surface of the cortical parenchyma.

Multi-channel signal separation by decorrelation

Abstract: Identification of an unknown system and recovery of the input signals from observations of the outputs of an unknown multiple-input, multiple-output linear system are considered. Attention is focused on the two-channel case, in which the outputs of a 2*2 linear time invariant system are observed. The approach consists of reconstructing the input signals by assuming that they are statistically uncorrelated and imposing this constraint on the signal estimates. In order to restrict the set of solutions, additional information on the true signal generation and/or on the form of the coupling systems is incorporated. Specific algorithms are developed and tested. As a special case, these algorithms suggest a potentially interesting modification of Widrow's (1975) least-squares method for noise cancellation, where the reference signal contains a component of the desired signal. >

Exact and Large Sample ML Techniques for Parameter Estimation and Detection in Array Processing

Abstract: Sensor array signal processing deals with the problem of extracting information from a collection of measurements obtained from sensors distributed in space. The number of signals present is assumed to be finite, and each signal is parameterized by a finite number of parameters. Based on measurements of the array output, the objective is to estimate the signals and their parameters. This research area has attracted considerable interest for several years. A vast number of algorithms has appeared in the literature for estimating unknown signal parameters from the measured output of a sensor array.

A Monte Carlo investigation of optical pathlength in inhomogeneous tissue and its application to near-infrared spectroscopy

Abstract: In order to quantify near-infrared spectroscopic (NIRS) data on an inhomogeneous medium, knowledge of the contribution of the various parts of the medium to the total NIRS signal is required. This is particularly true in the monitoring of cerebral oxygenation by NIRS, where the contribution of the overlying tissues must be known. The concept of the time point spread function (TPSF), which is used extensively in NIRS to determine the effective optical pathlength, is expanded to the more general inhomogeneous case. This is achieved through the introduction of the partial differential pathlength, which is the effective optical pathlength in the inhomogeneous medium, and an analytical proof of the applicability of the modified Beer-Lambert law in an inhomogeneous medium is shown. To demonstrate the use of partial differential pathlength, a Monte Carlo simulation of a two-concentric-sphere medium representing a simplified structure of the head is presented, and the possible contribution of the overlying medium to the total NIRS signal is discussed.

Subspace-based signal analysis using singular value decomposition

Abstract: A unified approach is presented to the related problems of recovering signal parameters from noisy observations and identifying linear system model parameters from observed input/output signals, both using singular value decomposition (SVD) techniques. Both known and new SVD-based identification methods are classified in a subspace-oriented scheme. The SVD of a matrix constructed from the observed signal data provides the key step in a robust discrimination between desired signals and disturbing signals in terms of signal and noise subspaces. The methods that are presented are distinguished by the way in which the subspaces are determined and how the signal or system model parameters are extracted from these subspaces. Typical examples, such as the direction-of-arrival problem and system identification from input/output measurements, are elaborated upon, and some extensions to time-varying systems are given. >

Microminiature, monolithic, variable electrical signal processor and apparatus including same

Abstract: A microminiature, variable electrical device, such as a capacitor (40a), comprises an elemental DMD SLM (40'), which includes a substrate (43) and a member (145) spaced therefrom and mounted for movement by appropriate facilities (42, 44). A control signal (102) is applied to the movable member (145) to produce an electric field between it and either the substrate (43) or an associated control electrode (46a). The field moves the member (145) toward or away from either the substrate (43) or an associated output electrode (46b) to selectively adjust the spacing therebetween. The field is produced by addressing circuitry (45) associated with the substrate (43). The movable member (145) and either the substrate (43) or the output electrode (46b) function as capacitor plates, and the spacing determines the capacitance thereof. The capacitor (40a) may be placed in series (FIG. 4) or in parallel (FIG. 3) with an input signal (114) applied to the movable member (145). The movable member (145), substrate (43), control electrode (46a), output electrode (46b), addressing circuitry (45), and other elements of the capacitor (40a) comprise a monolithic structure resulting from the use of MOS, CMOS or similar fabrication techniques. Multiple capacitors may be included in transmission lines (FIG. 20), antennae (FIG. 22), couplers (FIG. 21), waveguides FIG. 25) and other apparatus for digital or analog tuning or capacitance adjustment thereof by selective operation of the addressing circuitry (45).

System for monitoring patient location and data

Abstract: A patient monitoring system utilizes a transmitter associated with each patient The transmitter is worn by a patient and includes sensors operative to monitor vital signs of the patient The transmitter transmits an allocated RF frequency which is particularly associated with that patient A series of antennas are incorporated in a building, each antenna having its own signature signal As the patient moves throughout the building, the antennas pick up the signals from the patient's transmitter and combines the antenna signature signal with the transmitted patient signal This combined signal is then analyzed at a central location to determine the exact location of the patient due to the antenna signature signal which is modulated on the transmitted patient signal Transmitted patient data is also decoded at the central station to provide a signal indicative of the vital signs of the patient

Automatic tuning radio/tv using filtered seek

Abstract: A video processing device for automatic tuning of an audio-video signal (86) in accordance with a topic selection (80) made by a user. A user makes a selection of a subject matter topic from a menu (82) and the necessary tuning is thereafter automatically done under control of a menu control interface (82). In the example of digital information (90) transmitted in the vertical blanking interval of a video signal, the menu control interface (82) automatically adjusts the tuner (88) in accordance with the menu selection made by the user to choose an arbitrary channel and page of information within the channel. The menu or menus can be received from the incoming information, or can be stored in a memory (100).

Electrical stimulation for treatment of incontinence and other neuro-muscular disorders

Abstract: The invention is concerned with electrical stimulation for the treatment of neuro-muscular disorders, in particular incontinence. There is disclosed a portable electrical stimulation apparatus for treatment of incontinence, comprising one or more electrodes (302) for applying one or more electrical stimulation signals to a patient's body, a signal generator for generating the electrical stimulation signal(s), one or more conductive leads for connecting the signal generator to the electrode(s), to deliver the electrical stimulation signal to the electrode(s); and a power supply, characterised in that the apparatus includes an instruction storage means or a programming means for imparting a set of instructions to the signal generating means, the signal generating means being responsive to the instruction storage means or programming means so that the generated signal adopts signal waveform characteristics selected in accordance with said set of instructions.

Pseudorandom noise ranging receiver which compensates for multipath distortion by dynamically adjusting the time delay spacing between early and late correlators

Abstract: A receiver for pseudorandom noise (PRN) encoded signals consisting of a sampling circuit, multiple carrier and code synchronizing circuits, and multiple digital autocorrelators. The sampling circuit provides digital samples of a received composite signal to each of the several receiver channel circuits. The synchronizing circuits are preferably non-coherent, in the sense that they track any phase shifts in the received signal and adjust the frequency and phase of a locally generated carrier reference signal accordingly, even in the presence of Doppler or ionospheric distortion. The autocorrelators in each channel form a delay lock loop (DLL) which correlates the digital samples of the composite signal with locally generated PRN code values to produce a plurality of (early, late), or (punctual, early-minus-late) correlation signals. Thus, during an initial acquisition mode, the delay spacing is relatively wide, on the order of approximately one PRN code chip time. However, once PRN code synchronism has been achieved, the code delay spacing is narrowed, to a fraction of a PRN code chip time. There are several advantages to this arrangement, especially in environments wherein multipath distortion in the received composite signal is of the same order of magnitude as a PRN code chip time.

Radar signal processor

Abstract: A radar system includes a radar transceiver for generating transmit signals and for receiving signals reflected by targets. The radar system includes a mixer for combining the transmit signals and the reflected signals into a mixer signal. A radar signal processor includes a sampling device, connected to the mixer, for sampling the mixer signal and for generating a sampled mixer signal. A spectrum estimation device, connected to the sampling device, generates a range profile signal including a plurality of range bins each containing a magnitude of a spectral component. A threshold device, connected to the spectrum estimation device, generates a target space array from the range profile signal. A target decision device, connected to the threshold device, generates estimated range and speed signals for a closest target from the target space array.

Color phase control for projection display using spatial light modulator

Abstract: A SLM-based projection display system (10) samples and processes video data for delivery to a spatial light modulator (SLM) (13c), and uses a color wheel (14a) to color the SLM-generated images. A frame memory (13b) provides data to the SLM (13c) and is managed so that, if the phase of the incoming video signal changes, a desired phase relationship between the color wheel position and the data available to the SLM (13c) can be maintained. Also, a motor control unit (15a) uses a horizontal sync signal to generate a drive signal for the color wheel motor (16a), which limits the transient time during phase-changing events, and which provides a means for adjusting the phase of the drive signal.

Electrical current source circuitry for a bus

Abstract: Electrical current source circuitry for a bus is described. The circuitry includes transistor circuitry coupled between the bus and ground for controlling bus current, control circuitry coupled to the transistor circuitry, and a controller coupled to the control circuitry for controlling the transistor circuitry. The controller comprises a variable level circuit comprising setting circuitry for setting a desired current for the bus and transistor reference circuitry coupled to the setting circuitry. The variable level circuit provides a first voltage. Voltage reference circuitry provides a reference voltage. Comparison circuitry is coupled to the voltage reference circuitry and to the variable level circuit for comparing the first voltage with the reference voltage. Logic circuitry is responsive to a trigger signal from the comparison circuitry. An output of the logic circuitry is coupled to the control circuitry in order to turn on the transistor circuitry in a manner dependent upon an output of the logic circuitry.

Electro-optic vision system which exploits position and attitude

Abstract: The present invention is generally concerned with electronic vision devices and methods, and is specifically concerned with image augmentation in combination with navigation, position, and attitude devices. In the simplest form, devices of the invention can be envisioned to include six major components: A 1) camera to collect optical information about a real scene and present that information as an electronic signal to; a 2) computer processor; a 3) device to measure the position of the camera; and a 4) device to measure the attitude of the camera (direction of the optic axis), thus uniquely identifying the scene being viewed, and thus identifying a location in; a 5) data base where information associated with various scenes is stored, the computer processor combines the data from the camera and the data base and perfects a single image to be presented at; a 6) display whose image is continuously aligned to the real scene as it is viewed by the user. The present invention is a vision system including devices and methods of augmented reality wherein an image of some real scene is altered by a computer processor to include information from a data base having stored information of that scene in a storage location that is identified by the real time position and attitude of the vision system. It is a primary function of the vision system of the invention, and a contrast to the prior art, to present augmented real images and data that is continuously aligned with the real scene as that scene is naturally viewed by the user of the vision system. An augmented image is one that represents a real scene but has deletions, additions and supplements.

Apparatus and method for reducing power consumption in a mobile communications receiver

Abstract: A system for reducing receiver power consumption in communication system having a transmitter (141) and one or more receivers (146) schedules periodic message in 'slot'. Each receiver is assigned a slot during which it monitors the transmission. The transmitter (141) transmits messages to the receiver only during the assigned slots. The receiver is in an 'active state' during its assigned slot. During the 'inactive state', which is the time period between successive occurrences of its assigned slot, the receiver may perform any action not requiring coordination with transmitter. At a time during the inactive state shortly before the assigned slot, the receiver applies power to these components and performs initialization. Such initialization may include reacquiring a pilot channel signal to which the receiver may synchronize itself if its timing signal have drifted out of synchronization with those of the transmitter during the preceding inactive state.