Showing papers on "Signal published in 1982"

Adaptive filter model of the cerebellum

Abstract: The Marr-Albus model of the cerebellum has been reformulated with linear system analysis. This adaptive linear filter model of the cerebellum performs a filtering action of a phase lead-lag compensator with learning capability, and will give an account for the phenomena which have been termed "cerebellar compensation". It is postulated that a Golgi cell may act as a phase lag element; for example, as a leaky integrator with time constant about several seconds. Under this assumption, a mossy fiber-granule cell-Golgi cell input network functions as a phase lead-lag compensator. Output signals from Golgi-granule cell systems, namely, parallel fiber signals, are gathered together through variable synaptic connections to form a Purkinje cell output. From a general theory of adaptive linear filters, learning principles for these modifiable connections are derived. By these learning principles, a Purkinje cell output converges to the "desired response" to minimize the mean square error of the performance. In a more general sense, a Purkinje cell acquires a filtering function on the basis of multiple pairs of input signals and corresponding desired output signals. The mode of convergence of the output signal is described when the input signal is sinusoidal.

Signal cancellation phenomena in adaptive antennas: Causes and cures

Abstract: Conventional adaptive beamformers utilizing some form of automatic minimization of mean square error exhibit signal cancellation phenomena when adapting rapidly. These effects result from adaptive interaction between signal and interference, when signal and interference are received simultaneously. Similar phenomena have been observed and analyzed in relatively simple adaptive noise cancelling systems. A study of these phenomena in the simpler systems is used to provide insight into similar behavior in adaptive antennas. A method for alleviating signal cancellation has been devised by Duvall, whereby the signal components are removed from the adaptive process, then reinserted to form the final system output. Widrow has devised a different solution to the problem: to move the receiving array spatially (or electronically) to modulate emanations received off the look direction, without distorting useful signals incident from the look direction. This approach is called "spatial dither" and introduces the additional possibility of modulating "smart" jammer signals, thereby limiting their effectiveness.

Forward masking as a function of frequency, masker level, and signal delay

Abstract: The forward masking of a sinusoidal signal by a sinusoid of the same frequency was investigated for frequencies ranging from 125 to 4000 Hz. Forward masking in dB is proportional to both masker level and log signal delay at each frequency. More forward masking occurs at very low frequencies than at high frequencies, given equal‐sensation‐level maskers, and masked thresholds are greater at low frequencies than at high frequencies given equal‐SPL maskers. The data can be described equally well by assuming that the difference in forward masking as a function of frequency is due to a change in the time course of recovery from masking or to a change in the growth of masking at each signal delay. The frequency effect is not large enough to change the interpretation of forward‐masking data in studies of suppression or psychophysical tuning curves.

Implantable dynamic pressure transducer system

Abstract: A pressure and motion transducer and cooperating circuitry for an implantable medical device are disclosed. The system includes a pressure transducer 48 and buffer amplifier 40. A clock 70 in pacer 52 periodically energises amplifier 40 via capacitor 62 and lead system 54. The voltage sensed across sensing resistor 74 at node 78 is applied to sample and hold circuit 66 and a continuous pressure signal is provided at output terminal 82.

Broadcast signal recognition system and method

Abstract: The method for the automatic electronic recognition of a program unit broadcast by radio waves includes the formation of a plurality of reference signal segments from the program unit and the processing of such segments to obtain digitized reference signal segments which are then normalized and stored. When the program unit is broadcast, the broadcast signal is processed to generate successive digitized broadcast signal segments which are correlated with the digitized, normalized reference signal segments to obtain correlation function peaks for each resultant correlation segment. The spacing between the correlation function peaks for each correlation segment is then compared to determine whether such spacing is substantially equal to the reference signal segment length. Also, the RMS value coincident with each correlation function peak is determined and the pattern of such RMS values coincident with the correlation function peaks is compared with the pattern of the RMS values of the normalized reference signal segments.

Speed control system for small medical motors

Abstract: A speed control system for small medical motors. The system comprises a drive voltage regulation circuit, a current detection circuit which generates a detection signal in accordance with motor current, a voltage detection circuit which generates a detection signal in accordance with motor voltage, and a speed control circuit which controls the drive voltage regulation circuit in accordance with the detection signals of both detection circuits. With this system, the detection signal of the current detection circuit is positive-fed back, and the detection signal of the voltage detection circuit is negative-fed back to the speed control circuit to keep motor speed constant by effectively coping with abrupt load fluctuation.

Speech recognition system for an automotive vehicle

Abstract: A speech recognition system includes speech presence detection which uses a first level threshold of ambient noise/silence above which speech start is decided for a signal. Speech end is decided when the signal falls to a second threshold equal to the first, unless a predetermined time interval of speech is exceeded after start, causing a corrected second threshold to be calculated and used.

Coin detector system

Abstract: An electronically controlled coin tester which positions a sample coin in a magnetic field then passes a test coin through a similar magnetic field to create a null in a detector coil sensing the fields. The output of a square wave oscillator is differentiated to generate a spiked signal for exciting the magnetic field. The presence of the test coin is detected by sensing the quality of the null and test coin is accepted in response to the duration of the null. Preferably, a capacitor is charged in the absence of the test coin and discharged in the presence of the test coin and the test coin is accepted in response to the amount of energy stored in the capacitor at the time the null is produced. In addition, a pendulum damper is provided for engaging the test coin prior to its entry into the magnetic field and variably retarding the test coin in response to the coin size.

Image sensor assembly

Abstract: A compact image sensor package for use in an endoscope or borescope in which a lens system, a solid state image sensor and a circuit board are mounted in tandem within a cylindrical sealed housing. The assembly is positioned within the viewing head of the instrument so that an image of a given target is recorded on the sensor and an electrical output signal indicative of the image data is transmitted out of the package via either an optical or electrical transmission line.

Data adaptive signal estimation by singular value decomposition of a data matrix

Abstract: A new method is presented for estimating the signal component of a noisy record of data. Only a little prior information about the signal is assumed. Specifically, the approximate value of rank of a matrix which is formed from the samples of the signal is assumed to be known or obtainable from singular value decomposition (SVD).

Teleconferencing method and system

Abstract: Control of teleconference is facilitated so as to allow relatively unskilled operators to implement such control. The invention includes at least a pair of teleconferencing sites, each of which includes at least a pair of controllable video sources for deriving video signals from controllable regions of the associated site, an audio source for deriving an audio signal from the associated site, at least a pair of video displays for controllably displaying either locally or remotely generated images, an audio transducer responsive to a remotely generated audio signal for generating perceptible sound, an interface for coupling digital representations of locally generated audio and video signals to a communication link linking the sites and for coupling digital representations of remotely generated audio and video signals, a control device including a digital microprocessor and controlling, among other things, a video matrix switch, the video matrix switch having plural video inputs and outputs for controllably coupling at least a locally generated video signal to the interface and for controllably coupling locally and/or remotely generated video to said displays. The control device also includes a control video display with a touch sensitive screen for controlling the video sources and video matrix switch in response to touches on the touch sensitive screen by an operator and further including, in the form of a program in said microprocessor, apparatus to interpret commands initiated by operator touches of the touch sensitive screen and for thereafter implementing the commands if elements of the command are consistent with each other and with available resources as well as message formatting which are responsive to the logic for formatting digital messages destined for the video sources and the video matrix switch.

Cochannel Interference Considerations in Frequency Reuse Small-Coverage-Area Radio Systems

Abstract: Frequency reuse small-coverage-area radio systems having hexagonal and square coverage areas are compared. Comparison is made on the basis of average signal to average interference (\bar{S}/\bar{I}) in the corners of the areas and on the basis of the expected probability of S/I exceeding some system threshold for at least one base station that is eligible to provide service. The difference in performance between square and hexogonal systems is small, smaller than the usual uncertainties in the propagation parameters needed in the performance estimates. Results suggest that, even if the signal strength decreases as slowly as the inverse cube of the distance and the standard deviation of the large scale signal variation is as large as 10 dB, good service probabilities (on the order of 99 percent) can be provided in small-coverage-area radio systems using 30-40 channel sets.

Remote level adjustment system for use in a multi-terminal communications system

Abstract: A remote level adjustment system for use in a multi-terminal communications system wherein a plurality of remote terminals are connected to a master terminal by a distribution network for bi-directional transmission of signals. The remote terminals are adapted to transmit and receive signals on the network and respond to a polling signal by transmitting signals regarding transactions at respective sites. Each remote terminal includes circuitry for responding to level-setting signals by transmitting reply signals, and variable attenuation circuitry for adjusting, in response to a level-setting adjustment signal, the power level of the signals it transmits. The master terminal is adapted to transmit and receive signals on the network and includes program and circuit means for transmitting a polling signal. The master terminal further includes program and circuit means for transmitting level-setting signals, for measuring the power level of reply signals from selected remote terminals and deciding whether to adjust the level, and for transmitting a level-setting adjustment signal, if necessary, to command the selected remote terminal to adjust the setting of its variable attenuation circuitry in accordance with a level-setting protocol.

A Guide to the Use of the ITS Irregular Terrain Model in the Area Prediction Mode

Abstract: The ITS model of radio propagation for frequencies between 20 MHz and 20 GHz (the Longley–Rice model) is a general purpose model that can be applied to a large variety of engineering problems. The model, which is based on electromagnetic theory and on statistical analyses of both terrain features and radio measurements, predicts the median attenuation of a radio signal as a function of distance and the vari-ability of the signal in time and in space. The model is described in the form used to make "area predictions" for such applications as preliminary estimates for system design, military tactical situations and surveillance, and land–mobile sys-tems. This guide describes the basis of the model, its implementation, and some advantages and limitations of its use. Sample problems are included to demonstrate applications of the model.

Optical reading apparatus with automatic gain control circuit

Abstract: In an optical reading apparatus having a reading sensor for converting optically readable information into an electrical analog signal, an automatic gain control circuit is provided to maintain the amplitude of the electrical signal constant. The gain of the automatic gain control circuit is controlled such that the average or peak voltage of the electrical signal derived from the reading sensor is detected and held until next scanning effected by the reading sensor so that a variable impedance element included in the automatic gain control circuit will be controlled in accordance with the held voltage to maintain the amplitude of the electrical signal constant.

Method and device for analyzing a very high frequency radiation beam of electromagnetic waves

Abstract: The invention refers to the analysis of a very high frequency radiation beam of electromagnetic waves. According to the invention, a network of conductor wires is placed in the path of a beam to be analyzed, the wires being interrupted at intervals by switches. One controls the conducting state of a diode and one blocks the others and one makes the position of the diode vary electronically and sequentially in the conducting state. The return signal received on a sensor R is used by detecting the significant characteristics of that return according to the position of the diodes in the conducting state.

Programmable signal processing device

Abstract: Programmable signal processing device mainly intended for heanng aids and of the kind which includes an electronically controlled signal processor, the device being able to select a number of different signal processes to suit different sound situations automatically or by the user himself. This is accomplished by a memory (6) arranged to store information data for at least two unique signal processes adjusted to different sound environment/listening situations and a control unit (5), manual or automatic, arranged to transmit information data for one of the unique signal processes from the memory (6) to the signal processor (4) to bring about one signal process adjusted to a particular sound environment/listening situation.

Wide-band microwave signal coupler

Abstract: A microwave coupler for coupling microwave energy from a first waveguide to a second waveguide disposed side by side along a propagation length includes a common coupling means, and specifically, orifices along the propagation length wherein the coupling orifices are sized to promote coupling of a favored field mode of electromagnetic energy according to a Bessel function distribution of energy along the length of the waveguide. The Bessel function distribution provides for wideband, low-loss coupling of the favored field mode and maximal isolation from non-favored field modes. The invention is particularly useful for extracting a type TE21 circular mode signal from a signal containing TE11 and TE21 circular modes wherein the TE21 mode signals are used for generating elevational and azimuthal tracking signals.

A Central Limit Theorem for Stationary Processes and the Parameter Estimation of Linear Processes

Abstract: A central limit theorem is proved for the sample covariances of a linear process. The sufficient conditions for the theorem are described by more natural ones than usual. We apply this theorem to the parameter estimation of a fitted spectral model, which does not necessarily include the true spectral density of the linear process. We also deal with estimation problems for an autoregressive signal plus white noise. A general result is given for efficiency of Newton-Raphson iterations of the likelihood equation.

Microbending of optical fibers for remote force measurement

Abstract: A system for remote measurement of structural forces includes a plurality of microbend transducers mounted along the length of the structure for microbending an optical fiber in response to structural forces, such as stress acting upon an oil or gas pipeline or the like. An optical time domain reflectometer (OTDR) has a light source for launching a pulsed optical signal for passage through the fiber and a photodetector for sensing as a function of time the intensity of backscattered light reflected back through the fiber, wherein this sensed time function is correlated directly with discrete longitudinal positions along the length of the fiber and the structure. When one or more of the microbend transducers is activated to induce a microbend in the fiber in response to localized forces acting upon the structure, a portion of the backscattered light is lost at the microbend. This attenuation in backscattered light intensity is sensed quantitatively and positionally identified by the photodetector. Specific preferred constructions for microbend transducers and system arrangements particularly adapted for detecting structural strain in an oil or gas pipeline are disclosed.

AC-DC Converter having an improved power factor

Abstract: An AC to DC converter utilizes a first power converter for converting an AC signal to a DC signal under the control of a control signal. The control signal is generated by a control circuit that includes a first analog generator that provides a first signal that is analogous to the voltage of the AC signal that is to be converted. A second analog generator generates a second signal that is analogous to the current of the AC signal that is to be converted and a third analog generator generates a third signal that is analogous to the voltage of the DC output signal. The third signal and the first signal are multiplied together to obtain a fourth signal. The control signal is generated from the fourth signal and the second signal and is used to control the power converter such that the waveform of the current of the AC signal is limited to a sinusoidal waveform of the same frequency and phase as the AC signal.

Computer terminal security system

Abstract: The invention provides a system for securing the access of a remote computer terminal (130) to a centrally located host computer (300). The system includes a first security circuit (200) interconnected with a calling telephone (100), a calling modem (110), and the remote computer terminal (130) at the remote location for automatically dialing the number of the called telephone (310) at the location of the central host computer (300). A second security circuit (350) is located at the central host computer (300) and is interconnected with the called telephone (130), the called modem (330), and the central host computer (300). Upon receipt of the user identification code, the second security circuit (350) compares the user identification code with a stored code and, if verified, sends an acknowledgment signal back to the first security circuit (200). At this time, the two security circuits (200 and 350) activate respective solid state switches (260 and 370) to interconnect the host computer (300) with the remote computer terminal (130). A portable memory module (240) is selectively insertable in the first security circuit (200) to selectively activate and deactivate the first security circuit and which contains the secret phone number of the called telephone (310) at the host computer (300) as well as the secret user identification code.

Randomized tag to portal communication system

Abstract: Communication between portal units and identification tags is accomplished by continually radiating an interrogation signal consisting of a code pattern from each portal unit followed by a listening interval. Tags within range of such interrogation signal test the incoming signals for frequency, bit duration, bit rate, a preamble code and a facility identifying code. If the tag receives a valid signal to which it has been preprogramed, such signal synchronizes and initiates a plurality of tag responses within a given overall response interval and with each response transmitted during randomly selected time slot. Each tag is provided with its own pseudorandom binary sequence generator and reply counter with the pseudorandom generator sequenced by a signal derived from the carrier signal radiated by the tag. The portal units also test incoming signals for frequency bit rate and bit duration as well as for a preamble code generically indicative of a tag. If the test is passed, the remaining tag response consisting of an identifier and an error correcting code is accepted and passed on to a CPU.

State of charge indicator

Abstract: A method and apparatus for producing a visual signal of the state of charge of a battery selectively connected and disconnected from an external load. A test load is connected to the battery for a predetermined period of time to draw a current pulse from the battery when the battery is disconnected from the external load. Simultaneously, the voltage of the battery is measured. The measured voltage is converted to a digital signal, and the digital signal is transmitted to a storage means. The stored signal is then transmitted to a visual display device.

Reduced memory graphics-to-raster scan converter

Abstract: A system and technique is disclosed which enables a reduction in memory for the display of superimposed data (alpha-numerics, symbols and graphics) in an all-raster scanned display. A video signal containing information to be displayed on a video monitor by raster scanning techniques is multiplexed with the output of a storage device containing information representing data for controlling the intensity of specific points on the monitor during the raster scan. The intensity is controlled by the signals from memory to produce data on the video monitor as an overlay to the normal video display produced by the video signal. In one embodiment, the storage device is formed by two separate memory areas having a size substantially less than the total number of lines forming one raster field of the video display. The first memory area is multiplexed with the video signal while the second memory area is being filled and the second memory area is multiplexed with the video signal while the first memory area is being filled. This process is repeated a predetermined number of times for each field scan of the video display.

Capacitance-type material level indicator

Abstract: A system and probe for indicating the level of material in a vessel as a function of material capacitance comprising a resonant circuit including a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An rf oscillator has an output coupled to the resonant circuit and to a phase detector for detecting variations in phase angle as a function of probe capacitance. Level detection circuitry is responsive to an output of the phase detector and to a reference signal indicative of a predetermined level of material for indicating material level as a function of a difference between capacitance at the probe and the reference signal. In the preferred embodiments of the invention disclosed, an automatic calibration circuit adjusts the resonance characteristics of the parallel resonant circuit of the reference signal indicative of a predetermined reference material level.

Acoustical defect detection system

Abstract: The vibration of a moving device which has repetitive movements, for instance a rotary compressor, are sensed at the outer case and analyzed in real time in both the time and frequency plane. For the time analysis the envelope of the signal is generated; for the frequency analysis a fast Fourier transform is performed and separate power spectra for fractions of a revolution are produced. The signatures are compared with those of an acceptable device to identify rejects and abnormalities at a particular position of a moving part.

Remote control of dimmable electronic gas discharge lamp ballasts

Abstract: A remotely controlled dimming solid state ballast system for gas discharge lamps adapted to respond to external control signals is disclosed which includes the ballast itself along with integral controls for interfacing with an external addressing control system, which may be a powerline carrier system. The external control system includes a signal receiver for receiving, and recognizing remotely transmitted control signals addressed to said ballast. An output device is provided for generating an output control signal modulated in response to the control signals to provide the desired control setpoint of the lamps controlled by the ballast or to turn the lamps on or off.