Showing papers on "Signal published in 1985"

Coherent signal-subspace processing for the detection and estimation of angles of arrival of multiple wide-band sources

Abstract: This paper presents a method of constructing a single signal subspace for high-resolution estimation of the angles of arrival of multiple wide-band plane waves. The technique relies on an approximately coherent combination of the spatial signal spaces of the temporally narrow-band decomposition of the received signal vector from an array of sensors. The algorithm is presented, and followed by statistical simulation examples. The performance of the technique is contrasted with other suggested methods and statistical bounds in terms of the determination of the correct number of sources (detection), bias, and variance of estimates of the angles.

Measurement of signal intensities in the presence of noise in MR images

Abstract: Power spectrum or magnitude images are frequently presented in magnetic resonance imaging. In such images, measurement of signal intensity at low signal levels is compounded with the noise. This report describes how to extract true intensity measurements in the presence of noise.

Multirate digital signal processing

Abstract: There has been a great deal of material in the area of discrete-time transforms that has been published in recent years. This book does an excellent job of presenting important aspects of such material in a clear manner. The book has 11 chapters and a very useful appendix. Seven of these chapters are essentially devoted to the Fourier series/transform, discrete Fourier transform, fast Fourier transform (FFT), and applications of the FFT in the area of spectral estimation. Chapters 8 through 10 deal with many other discrete-time transforms and algorithms to compute them. Of these transforms, the KarhunenLoeve, the discrete cosine, and the Walsh-Hadamard transform are perhaps the most well-known. A lucid discussion of number theoretic transforms i5 presented in Chapter 11. This reviewer feels that the authors have done a fine job of compiling the pertinent material and presenting it in a concise and clear manner. There are a number of problems at the end of each chapter, an appreciable number of which are challenging. The authors have included a comprehensive set of references at the end of the book. In brief, this book is a valuable contribution to the general areas of signal processing and communications. It can be used for a graduate level course in perhaps two ways. One would be to cover the first seven chapters in great detail. The other would be to cover the whole book by focussing on different topics in a selective manner. This book by Elliott and Rao is extremely useful to researchers/engineers who are working in the areas of signal processing and communications. It i s also an excellent reference book, and hence a valuable addition to one’s library

Fast Algorithms for Digital Signal Processing

Abstract: Fast algorithms for digital signal processing , Fast algorithms for digital signal processing , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Broadcast program identification method and apparatus

Abstract: A method and apparatus for identifying repetitively broadcast programs, such as commercial advertisements broadcast on television and radio, detects the occurrence of predetermined events in a video signal and/or in an audio signal, detects a stability condition and extracts a signature from the video and/or audio signal. The signatures and the times of occurrence of the signatures are stored and subsequently compared with reference signatures to identify the program and its time of broadcast. The reference signatures may be obtained by identifying repetitively extracted, unidentified signatures and indexing a recording of the video and/or audio signals to enable the system user to identify the unidentified broadcast program and store the previously unidentified signatures as additional reference signatures in memory.

A role for the magnetic field in the radiation-induced efflux of calcium ions from brain tissue in vitro

Abstract: Two independent laboratories have demonstrated that electromagnetic radiation at specific frequencies can cause a change in the efflux of calcium ions from brain tissue in vitro. In a local geomagnetic field (LGF) at a density of 38 microTesla (microT), 15- and 45-Hz electromagnetic signals (40 Vp-p/m in air) have been shown to induce a change in the efflux of calcium ions from the exposed tissues, whereas 1- and 30-Hz signals do not. We now show that the effective 15-Hz signal can be rendered ineffective when the LGF is reduced to 19 microT with Helmholtz coils. In addition, the ineffective 30-Hz signal becomes effective when the LGF is changed to +/- 25.3 microT or to +/- 76 microT. These results demonstrate that the net intensity of the LGF is an important variable. The results appear to describe a resonance-like relationship in which the frequency of the electromagnetic field that can induce a change in efflux is proportional to a product of LGF density and an index, 2n + 1, where n = 0,1. These phenomenological findings may provide a basis for evaluating the apparent lack of reproducibility of biological effects caused by low-intensity extremely-low-frequency (ELF) electromagnetic signals. In future investigations of this phenomenon, the LGF vector should be explicitly described. If the underlying mechanism involves a general property of tissue, then research conducted in the ambient electromagnetic environment (50/60 Hz) may be subjected to unnoticed and uncontrolled influences, depending on the density of the LGF.

Blood flow: magnetic resonance imaging.

Abstract: The appearance of flowing fluid has been evaluated in several clinical situations using a flow phantom, computer simulation, and clinical magnetic resonance (MR) images. Unsaturated protons just entering the imaging volume can emit a strong signal relative to the partially saturated adjacent tissue ("flow-related enhancement"). Slow laminar flow in veins can be distinguished on the basis of a stronger second echo due to rephasing effects ("even echo rephasing"). Synchronization of the cardiac cycle and the MR pulsing sequence produces increased signal in sections acquired during diastole ("diastolic pseudogating"). Intraluminal signal is shown to decrease as velocity is increased ("high velocity signal loss"). Onset of turbulence causes further loss of signal. Direction of flow oblique to the imaging plane can be predicted on the basis of decreased upstream and increased downstream signal.

Digital global positioning system receiver

Abstract: A digital receiver for GPS C/A-code signals is described. The GPS receiver of the present invention provides reception and tracking a plurality of satellites simultaneously, using four separate receiver channels. The GPS receiver of the present invention includes an analog front-end for selecting and frequency translating the received GPS signal. The GPS receiver further includes a highspeed digital signal processor for recovering the despread data of the GPS signal. The baseband signal is further processed by a general purpose digital signal processor for signal search, tracking, and data recovery operations, and a microprocessor provides overall receiver control, and interface with the operator of the GPS receiver.

Programmable logic array device using EPROM technology

Abstract: The programmable logic array device basically comprises a programmable AND array (Figures 5, 11) having a plurality of memory cells (30, 31) arranged in addressable rows (40-45) and columns (32-38) and which can be individually programmed to contain logic data; an input circuit (Fig. 9) for receiving an input signal and for developing a buffered signal corresponding thereto; a first row driver (Fig. 10) responsive to the buffered signal and operative to interrogate a particular row of the memory cells and to cause the AND array to output signals corresponding to the data contained therein; first sensing circuitry (Fig. 12) for sensing the signals output by the AND array and for developing corresponding data signals which are the logical OR of signals output by the AND array; first output terminal circuitry; and first switching circuitry (Fig. 14) responsive to a control signal and operative to couple the data signal either into the storage circuitry or to the output terminal circuitry (Fig. 16). The device has the advantages general of greater logic density and lower system power than standard family logic components.

Multidimensional digital signal processing

Abstract: You must turn in your code as well as output files. Please generate a report that contains the code and ouput in a single readable format. Getting Started ˆ You may want to download Irfanview image viewing software. It handles pretty much any image type, lets you convert, and provides batch processing. ˆ Download the sample images from the class website. The following question operates on the city.jpg image. (a) Perform image smoothing using a 7×7 averaging filter and a Gaussian filter with σ = 0.5 and 3. Compare the outputs. (b) Perform edge enhancement using the Sobel operator (Matlab's default parameters). Repeat using the Laplacian and Laplacian of Guassian operators. Compare the outputs 2. Frequency Domain Filtering The following question operates on the city.jpg image. (a) Find the Fourier transform of the image. Be sure to center the frequencies. (b) Perform image smoothing in the frequency domain using the filters defined in the previous problem. Compare the output images from the two methods (spatial and frequency) and the time for operation. (c) Perform edge enhancement using the filters defined in the previous problem. (d) Define a lowpass filter in the frequency domain with radius of 1/4 the height. Show the result. Repeat with a similar sized Guassian and compare the results. Give the σ parameter you used and show the output transform image. (e) Repeat with a rectangular filter with the same dimension as the ideal lowpass. Compare the results between the ideal filter and the rectangular approximation. 3. Canny Edge Detection (a) Give the convolution kernels for determining the gradient. You may examine the function gradient.m to help with the explanation. (It may be easiest to apply the gradient to an impulse and inspect the results. (b) Implement the simplified version of the Canny edge detector (single scale). The syntax of the function should be where E contains the detected edges, M the smoothed gradient magnitude, A contains the gradient angle, I is the input image, sig is the σ parameter for the smoothing filter, and tau= [τ h , τ l ] is the two element vector containing the hysteresis thresholds. See Algorithm 6.4 for non-maximal suppression and Algorithm 6.5 for hysteresis thresh-olding. (It may be more efficient to implement the hysteresis as edge tracking)

Contrasting neuronal activity in supplementary and precentral motor cortex of monkeys. I. Responses to instructions determining motor responses to forthcoming signals of different modalities

Abstract: The present report contrasts neuronal activity in two motor cortical fields after instructions that determine which of two sensory signals will trigger a movement and which will not. The goal of the study was to determine possible differential roles of the two cortical fields in the process of preparing to move in response to one external cue and to ignore another. Single-cell recordings were made from the supplementary motor area (SMA) and the precentral motor area (PCM) of monkeys trained to perform key-press movements in two different modes. In the auditory mode, an instruction signal warned the animal to prepare to start the movement promptly in response to a forthcoming 1,000-Hz tone burst (trigger signal), but to remain motionless if the signal was vibrotactile (nontrigger signal). In the tactile mode, the trigger and nontrigger signals were reversed: a different instruction signal warned the animal to prepare to perform the key-press movement in response to the vibrotactile cue, but to withhold it in response to the 1,000-Hz tone. The instruction signals were auditory tones of 300 Hz for the auditory mode and 100 Hz for the tactile mode. Out of 259 task-related SMA neurons, 128 (49%) responded to instructions. Three types of instruction responses were observed: 1) 95 neurons showed continuous instruction-induced activity changes lasting until the occurrence of the movement-triggering signal, regardless of whether an intervening nontrigger signal occurred. 2) 24 neurons showed increased activity until the occurrence of the nontriggering signal, after which the activity subsided. When there was no nontrigger signal, the activity increased during a period when the nontrigger signal might have been given. 3) Nine neurons responded with a transient, short-latency discharge after the instruction. The responses of SMA neurons to two instructions were often different. Forty-four SMA neurons exhibited a selective response to only one of the two instructions. In 43 neurons the response was differential, with the magnitude of activity increase or decrease being at least three times greater after one instruction than the other. In the remaining 41 neurons the response was nondifferential. Out of 112 task-related PCM neurons, 25 (22%) responded to the instructions. In the majority of them (21 neurons), the instruction response was nondifferential.(ABSTRACT TRUNCATED AT 400 WORDS)

Implantable electromagnetic middle-ear bone-conduction hearing aid device

Abstract: An implantable electromagnetic middle-ear bone conduction hearing aid device is disclosed which provides variability to meet a variety of pathological entities of the hearing impaired user. The device utilizes a sound processing component for converting sound into an analog electromagnetic signal and has an output transmitter adapted to be placed supercutaneously on the skull of the user for transmitting the electromagnetic signal transcutaneously. A signal receiving and transmitting component is adapted to be implanted subcutaneously in the bone of the user outside of the middle ear for receiving the transcutaneous electromagnetic signal from the sound processing component and for transmitting the electromagnetic signal subcutaneously into the middle-ear of the user. A vibration generating component is adapted to be implanted in any of the small bones of the ossicular chain in the middle-ear for receiving the subcutaneous electromagnetic signal from the signal receiving and transmitting component and for vibrating the ossicular chain in response to such electromagnetic signal to stimulate normal functioning of the inner ear to create the perception of sound in the hearing impaired user.

Integrated radio location and communication system

Abstract: An integrated radio location and communication system comprising a plurality of radio locator-transmitter devices which may be fixed to vehicles and/or carried by persons and which are capable of transmitting the position and identity of said devices to two or more centrally located fixed receiver sites. Each of said locator-transmitters is continuously phase-locked to the RF carrier of a nearby commercial broadcast station, which station is modified slightly to provide periodic transmission of a "range-tone" which is on the order of a few kilohertz in frequency and is phase-locked to the RF carrier. An identical phase-locked range-tone is likewise generated within each locator-transmitter. The two centrally located fixed receivers are also phase-locked to the broadcast station RF carrier and likewise generate a range-tone. Thus the broadcast station, the plurality of locator-transmitters and the two fixed receiver sites all generate identical range-tones and these are continuously kept in synchronism with each other by virtue of a phase-lock loop arrangement wherein all range-tones are derived from (and locked to) the RF carrier of the AM broadcast station signal. The fixed receiver sites can compute the position of each locator-transmitter by comparing the phase of the range-tone sent to them directly by the locator-transmitter with the phase of the range-tone received directly from the broadcast station. A novel frame synchronization method is disclosed whereby the position (i.e., "time-slot") of each locator-transmitter emission and its RF subchannel uniquely identifies the emitting source and thus the location as well as identity of each of the many locator-transmitters.

Ultrasonic generating system with feedback control

Abstract: An ultrasonic generating system for coupling vibrating energy into a load, such as living tissue, has been described which employs a piezoelectric crystal having excitation electrodes on opposite faces thereof A feedback electrode is disposed on one face of the crystal adjacent to and insulated from one of the excitation electrodes to provide a feedback signal between the feedback electrode and the other excitation electrode A power supply is provided for applying excitation energy to the excitation electrodes The feedback signal is utilized to slave the frequency of the power supply voltage to the resonant frequency of the crystal and to disable the power supply when the impedance of the load applied to the crystal rises above a predetermined level

Attentional influences on noxious and innocuous cutaneous heat detection in humans and monkeys

Abstract: This study examines whether selective attention can influence sensory-discriminative aspects of nociception in humans and monkeys trained to detect innocuous and noxious thermal stimuli. Human subjects had two contact thermodes positioned bilaterally above the upper lip. Upon trial initiation both thermodes heated to either 39 degrees C, an innocuous warm temperature, or 45 degrees C, a slightly noxious temperature. After 4 to 9 sec, the temperature of one thermode increased an additional step of less than 1 degree C. Subjects released a button when they detected this second temperature increase (T2). Three types of trials were presented in order to assess the effects of spatially selective attention on thermal detection. On 40% of the trials a light correctly signaled the location of the thermode on which T2 would occur. On 10% of trials a light incorrectly signaled the location of T2. No signal was presented on the remaining trials. From the 45 degrees C base line, detection latencies were shortest in the correct signal condition, longest in the incorrect signal condition, and intermediate in the unsignaled condition. The percent of undetected T2s was greatest in the incorrect signal condition and least in the correct signal condition. From the 39 degree C base line, the detection latency in the incorrect signal condition was greater than in the unsignaled condition, but the latter latency was not different from the correct signal latency. In addition, the percent of undetected T2s was the same on all three types of trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Analog and digital telemetry system for an implantable device

Abstract: In an implantable device, transmission and reception of digital information is accomplished as well as the transmission and reception of analog information. The analog signal is FM modulated for transmission and the digital signal is phase modulated for transmission. The FM modulated signal is used as a clock in the phase encoding of the digital signal and thus provides a signal simultaneously carrying analog and digital information. Means for reception of the analog and digital information is taught. The use of PSK (phase shift keying) as the phase modulation scheme for transmission and reception is also taught.

Microprocessor controlled electrosurgical generator

Abstract: A microprocessor controlled electrosurgical generator provides plural ground-isolated and mutually isolated monopolar r-f cutting signals for respective surgical pencils to permit plural surgeons to use the same generator while maintaining independent control over output power and mode selection. A bipolar output signal is also isolated from ground and from the monopolar signals so that the removal of the dispersive patient return pad is not required when changing between monopolar and bipolar operation. Adjustment of the r-f cutting signal power level is effected by providing an adjustable d.c. bias level for an output amplifier. The d.c. bias level is derived from an a.c. control signal which is duty-cycle modulated in accordance with selected r-f power level settings. Digital phase control is employed to change the control signal duty cycle by subdividing the control signal cycle into precise count intervals and triggering a gate to pass the control signal through a rectifier to a filter for only the selected number of count intervals in each cycle as determined by a pre-settable counter. Negative feedback of the cutting signal to the input terminal of the output amplifier provides system stability during open circuit operation.

High-frequency surgical apparatus

Abstract: 1. High-frequency surgical apparatus with automatic control of the intensity of the electric arcs between the active electrode and the tissue to be out or to be coagulated, wherein, for establishing the size of the arc, an electrical signal dependent thereon is derived via a filter and is fed to a rectifier (7), the output signal (E) from which is fed to a control amplifier (5), in which this output signal (E) is compared either with the set-point signal (S) of a set-point transmitter (15) for the cutting operation or with the set-point (K) of a set-point transmitter (8) for the coagulation operation, and wherein the control amplifier (5) produces a signal (C), proportional to the difference of the signals E minus S or E minus K respectively, which signal (C) is supplied to an amplitude modulator (3), which controls the amplitude of the output voltage (U) of the power amplifier (4), characterized in that the filter (6) is so constructed that it passes at least one frequency of the non-harmonic frequencies of the basic frequency (f1 ) of the high-frequency oscillator (2) generated by the electric arc (11) between active electrode (12) and tissue (9) in the output (13, 14) and simultaneously sufficiently damps the basic frequency (f1 ) and also it harmonic frequencies that they do not have any influence upon the control signal (C), the at least one frequency being determined from the electrical voltage (U) or from the electrical current (1) between active electrode and tissue.

System for security processing of retailed articles

Abstract: A system for processing articles selected for purchase and bearing distinct identification codes comprises, in one version: (a) a code reader for generating an output signal indicative of such article identification code; (b) a conveyor for receipt and transport of such article; (c) an entrance sentry for defining an inlet to a secured zone extending along a portion of the conveyor and for generating an output signal indicative of entry of the article into the secured zone and of a measurable characteristic of the article; and (d) a controller for selective movement of the conveyor in respective article acceptance and article rejection senses. The controller is operable in several respects, namely, for storage, for each of a plurality of such articles, of a signal indicative of a predetermined value of the measurable article characteristic correlated with such article identification code, for response to the code reader output signal for comparison of such stored signal with the output signal of the sentry, and for operation of the conveyor selectively in response to the results of such comparison.

Cardiac signal real time monitor and method of analysis

Abstract: An apparatus for monitoring EKG information includes a programmable apparatus carried by an ambulatory patient for performing continuous, real-time analyses of EKG information derived from the patient. The apparatus facilitates the determination of the existence of various conditions based on these analyses which portend cardiac complications including myocardial ischemia, and arrhythemia activity and further instructs the patient on the manner of treatment required for the detected condition.

A wireless PBX/LAN system with optimum combining

Abstract: A wireless PBX or LAN system is disclosed that allows multiple, simultaneous users per channel for communication between a base station (20) and a plurality of remote terminals (10,12,14...16) by a combination of adaptive signal processing arrays using optimum combining at the base station for interference suppression and separation of desired signals, adaptive power control at the remote terminals to keep interference at acceptable levels, and adaptive retransmission with time division in the direction from the base station to the remote terminals for communication therebetween including sending power control information to the remote terminals. The adaptive signal processing arrays have a plurality of antennas (110) at the base station, permitting a plurality of users in any one channel. If after adaptation a user's signal cannot be received adequately, the user is dynamically reassigned to a different channel. Interference is minimized by keeping the signals transmitted from and received at the base station at the same power level. The received signals are kept at the same power level by extracting information about the power level of the signals received at the base station and by sending power control bits back to the corresponding remote terminal so that the signal level from the remote terminal may be adjusted either up or down until the power level of each of the signals received at the base station is at the same level. The transmitted signls are kept at the same power level by adaptive retransmission with time division.

Automotive suspension control system with road-condition-dependent damping characteristics

Abstract: A suspension control system for automotive vehicles automatically adjusts the damping strength of variable shock absorbers or other dampers in accordance with road surface conditions as recognized by frequency analysis of a vehicle height or vibration sensor signal. The sensor signal reflects vertical displacement of the vehicle body from the road surface and includes high-frequency components due solely to displacement of the wheels or unsprung mass relative to the road surface and low-frequency components due to displacement of the vehicle body or sprung mass. The sensor signal is filtered into these separate frequency bands, the amplitude of each of which is compared to a corresponding reference level. The results of comparison give an indication of the degree and scale of irregularities in the road surface; specifically, a high-amplitude low-frequency component indicates larger-scale bumps and dips capable of bouncing the vehicle whereas a strong high-frequency component reflects a rough-textured road surface, such as gravel. The comparison information is sent to a suspension system controller which causes actuation of the shock absorbers to a stiffer mode of operation when the low-frequency sensor signal components are relatively strong.

Emergency vehicle warning and traffic control system

Abstract: A system for providing early warning of the approach and egress of emergency vehicles in which the warning system provides a display to indicate the direction from which the emergency vehicle is approaching and in addition provides preemption control of the traffic signals at an intersection. A transmitter mounted on an emergency vehicle transmits a signal whenever it is on an emergency call which is received by infrared (I.R.) receivers positioned at an intersection to respond to the transmitted signals. The received signal is then processed by a master controller which in turn pre-empts operation of traffic signals to control traffic flow at the intersection to which the emergency vehicle is approaching. The master controller also provides an output to display signs facing approaching traffic on each road approaching the intersection which displays messages and symbols indicating the direction of the approaching emergency vehicle. Additionally, the display system indicates whether the emergency vehicle has passed through and is departing the intersection. After a predetermined interval when an emergency vehicle has passed through an intersection the display system is deactivated and the traffic signals are returned to the traffic light control system.

Ambulatory non-invasive automatic fetal monitoring system

Abstract: Fetal monitors for automatically and continuously monitoring the well-being of a fetus. The preferably ambulatory monitors include one or more fetal cardiac sensors for detecting the fetal heart rate. The sensors can be acoustic, electrocardiographic or bioimpedence types. Interference sensors are included for selectively sensing the principle interference components contained in the fetal cardiac sensor signals. The preferred microprocessor based signal processing system converts the sensor signals into digital format and transforms the signals from time domain into frequency domain and back into time domain after appropriate processing. Adaptive cancellation of interfering signals and other signal enhancing operations are disclosed. Analytical subsystems continuously analyze the fetal heart rate information and information from a fetal movement sensor to perform a fetal non-stress test. Subsystems for other analytical tests are also disclosed. Alarms warn the mother when fetal behavior is outside of preprogrammed acceptable limits of such analytical tests so that remedial action may be initiated. The monitoring system also preferably includes a sensor belt for properly and conveniently wearing the sensors and a control unit containing the signal processing and related components.

Global positioning system course acquisition code receiver

Abstract: A GPS satellite receiver is disclosed in which the frequency of the received satellite signal is down converted in a single step by a balanced mixer driven by a half-frequency local oscillator and the down-converted satellite signal is converted from analog-to-digital form by a hard limiter.

The resolution of overlapping echos

Abstract: We present a new method for estimating the number and arrival times for overlapping signals with a priori known shape from noisy observations received by a sensor. The method is based on a recently developed eigenstructure technique for multitarget direction finding with passive antenna arrays and exploits the structure of the received signal covariance matrix. This problem is important in various applications such as radar and sonar data processing, geophysical/seismic exploration, and biomedical engineering. In many of these applications, a known signal is launched into a scattering medium and the returning response-in the form of delayed overlapping echos in noise-has to be processed to yield information on the nature and location of scatterers. The method presented also solves more general problems of signal detection and resolution.