Showing papers on "Signal published in 1980"

The wigner distribution - a tool for time-frequency signal analysis part ii: discrete-time signals

Abstract: In this second part of the paper the Wigner distribution is adapted to the case of discrete-time signals. It is shown that most of the properties of this time-frequency signal representation carry over directly to the discrete-time case, but some.others cause problems. These problems are associated with the fact that in general the Wigner distribution of a discrete-time signal contains aliasing contributions. It is indicated that these aliasing components will not be present if the signal is either oversampled by a factor of at least two, or is analytic. 1. Introduetion In part I of this paper 1) the Wigner distribution (WD) of continuous-time signals was discussed, and it was shown that this function has some very interesting properties. The determination of this distribution function requires, like the spectrum, an integral of the Fourier type to be evaluated. Ideally this requires the signal to be known for all. time, but in practice windowing techniques can be used to relax this requirement. The effects of windowing on the WD were discussed in part 1. In general two different approaches can be distinguished to compute these Fourier-type integrals. The first is by means of analogue signal processing, and recently optical signal processing methods have been proposed for determining suitable approximations to the WD 2). The second approach is based on digital signal processing. This opens the way to apply computationally efficient methods for evaluating the discrete Fourier transform, but requires the concept of the Wigner distribution to be transferred to the case of discretetime signals. This is the aim of this part of the paper. As can be expected, the WD for discrete-time signals shows much similarity with that for continuous-time signals, but in some respects it has characteristic differences.

Reverberations and Amplitude Fluctuations in the Propagation of Sound in a Forest: Implications for Animal Communication

Abstract: Effective communication requires that the receiver not only detect the presence of a signal but also discriminate significant variations in signals. Consequently, both attenuation and degradation o...

An analysis of multiple correlation cancellation loops with a filter in the auxiliary path

Abstract: A technique known as a "multiple correlation cancellation loop" and also as the "LMS algorithm" is widely used in adaptive arrays for radar, sonar, and communications, as well as in many other signal processing applications. In this paper an analysis of this technique is extended to the case when a linear filter appears in the auxiliary signal path. A general solution to this problem is obtained and several examples for narrow-band and broad-band signals are presented.

Method of and apparatus for processing a radiation image

Abstract: A method and apparatus for processing a radiation image in a radiation image recording system in which a stimulable phosphor is stimulated with a scanning stimulating beam and the light emitted from the stimulable phosphor upon stimulation by the stimulating beam is detected by a detector which generates an output which is processed and used for recording a visible image on a recording material. In the processing of the detected output, an operation represented by a formula S'=Sorg+β (Sorg--Sus) is conducted, where Sorg is the original image signal detected by the detector, β is an emphasis coefficient, and Sus is an unsharp mask signal corresponding to a super-low spatial frequency at every scanning point. The unsharp masking process may be performed together with a gradation process, reduction of image size, smoothing process and the like. Further, the emphasis coefficient may be varied with either the original image signal Sorg or the unsharp mask signal Sus.

Detection, estimation, and classification with spectrograms

Abstract: A locally optimum detector correlates the data spectrogram with a reference spectrogram in order to detect (i) a known signal with unknown delay and Doppler parameters, (ii) a random signal with known covariance function, or (iii) the output of a random, time‐varying channel with known scattering function. Spectrogram correlation can also be used for maximum likelihood parameter estimation, e.g., estimation of delay or center frequency of a signal. To estimate an analog input signal from its spectrogram, a modified deconvolution operation can be used together with a predictive noise canceler. If no noise is added to the spectrogram, the mean‐square error of this signal estimate is independent of the window function that is used to construct the spectrogram. When estimates of specific signal parameters are obtained directly from the spectrogram, these estimates have mean‐square errors that depend upon both signal and window waveforms. Spectrogram correlation can be used for classification as well as for estimation and detection. Parameter estimators and detectors are, in fact, specialized kinds of classifiers.

Cable television with controlled signal substitution

Abstract: A signal substitution system for cable television applies substitute television program signals in at least one substitute channel to the transmission cable along with singal substitution control signals. The signal substitution control signals include a plurality of different terminal command signals and a plurality of different event command signals, each of the terminal command signals including a respective panelist address signal for identifying a respective panelist receiving station, and each of the event command signals including a normal channel identification signal for identifying a normal channel into which a substitute television program is to be switched. A controller at each panelist receiving station responds to the signal substitution control signals by selectively switching a substitute television program into a normal channel. The controller includes a generator of a local panelist address signal and a substitute channel selector for producing a substitute channel select signal corresponding to a substitute channel. A first comparator compares the received panelist address signal of each terminal command signal with the local panelist address signal and produces a first match signal when the signals match. A second comparator compares the received normal channel identification signal with a channel select signal selected by the viewer and produces a second match signal when the signals match. In response to the first and second match signals a substitute channel is substituted for the channel selected by the viewer for a period determined by the signal substitution control signals.

Spread spectrum arrangement for (de)multiplexing speech signals and nonspeech signals

Abstract: It is known to multiplex speech signals and nonspeech signals over a common communication path. One arrangement uses a portion of the frequency spectrum of the path for speech signals with the remainder for nonspeech signals. Another inserts data signals during gaps in the speech signals. Still another treats a speech signal as a carrier signal and modulates the speech signal with data signals. Unfortunately, users of such known arrangements experience excessive distortion or perceive others as encroaching on the path. These and other problems are mitigated by my improved signal processor (100, 200) for the spread spectrum (de)multiplexing of speech signals and nonspeech signals. In an illustrative embodiment, at a transmitter, a block (110) of speech signals may be converted (140) from a time domain to a frequency domain by a Fourier transformation. A Fourier component may be pseudo-randomly selected (130) from a subset of such components. Responsive to the selected component, a prediction (160) of the component may be substituted therefor, the prediction being thereafter modified (170), e.g., by its amplitude being incremented or decremented to reflect the multiplexing of a logic 1 or a logic 0 nonspeech signal. The modified prediction may be converted (150) back to the time domain for transmission to a receiver. At the receiver, a parallel demultiplexing (200) occurs for extracting (270) speech signals and nonspeech signals from the multiplexed signals.

Apparatus for testing physical condition of a subject

Abstract: The physical condition of a subject is tested by a transducer mounted on the subject which derives a first signal indicative of heart activity. An electronic instrument housing carried by the subject includes terminals responsive to the first signal and (a) an inertial member for monitoring the quantity of repetitive actions taken by a limb of the subject and for deriving a second signal indicative of the quantity, (b) a keyboard for enabling signals to be derived indicative of numerical quantities associated with plural physiological parameters of the subject, (c) a clock source for deriving timing signals, (d) a digital computer responsive to the first, second, timing and keyboard signals for deriving plural digital output signals indicative of different physical activities of the tested subject, (e) a visual digital indicator, (f) plural key switches, each associated with a different one of the physical activities, and (g) circuitry responsive to activation of the plural key switches for selectively coupling different ones of the plural output signals to the visual indicator so only one of the output signals is supplied to the indicator at a time.

Body stimulator output circuit

Abstract: A body implantable stimulator having an output capacitance. Provision is made to increase the charge rate of the capacitance for a predetermined period following an output stimulation signal.

An analysis of multiple correlation cancellation loops with a filter in the auxiliary path

Abstract: A technique known as a "multiple correlation cancellation loop" and also as the "LMS algorithm" is widely used in adaptive arrays for radar, sonar, and communications, as well as in many other signal processing applications. In this paper, an analysis of this technique is extended to the case when a linear filter appears in the auxiliary signal path. A general solution to this problem is obtained and several examples for narrowband and broad-band signals are presented.

Combined antenna-rectifier arrays for power distribution systems

Abstract: An electrical power distribution system wherein electromagnetic energy irradiates a large spatial area is configured to include an array of antenna-rectifier modules wherein the receive aperture of each module is established in accordance with the electromagnetic field intensity at the location of that particular module so as to provide the rectifier circuitry with a predetermined amount of electrical power. Each antenna-rectifier module includes an array of high impedance (e.g., antiresonant) dipoles that are spaced apart along a two-wire transmission line. The total number of dipoles employed is established to provide the desired receive aperture and the impedance of each dipole is established so that the total impedance of the array substantially matches that of the rectifier circuitry employed. The rectifier circuitry is enclosed in and electromagnetically shielded by a conductive housing that is removably interconnected with the array of antenna elements and first and second filtering circuits are included to respectively eliminate high frequency signal components that can be coupled to and radiated by the antenna structure and high frequency ripple within the DC output signal.

Half duplex integral vocoder modem system

Abstract: Disclosed is a system whereby in a transmit mode analog speech is sampled d converted digitally to 12 bits of accuracy and then fed into a fast Fourier transform (FFT) processor which analyzes the speech into spectral and pitch parameters. These parameters are then quantized into a data stream which acts as an input to a differential phase shift keying modulator. The modulator constructs a multi-tone modem output signal from a 25 tone stack which is converted to an analog signal which is fed into a communications channel. In the receive mode a modem input signal from the communications channel is fed through the same analog to digital converter which was used for input speech. A data stream is now provided which is coupled back into the same digital FFT processor which now operates to provide pitch spectral coefficients which are then separated and used by a synthesizer to reconstruct a speech waveform. The speech waveform is applied to a digital analog converter which is the same converter used to produce the line signal when the processor operates in the transmit mode. The FFT processor implements a single FFT algorithm which is used for both vocoder and modem processing in both the transmit and receive modes.

Gradation processing method and apparatus for radiation image recording system

Abstract: In a radiation image recording system in which a radiation image is once recorded in a stimulable phosphor and then read out and reproduced on a recording material, the gradation of the radiation image is processed to enhance the diagnostic efficiency and accuracy of the image. The radiation image is read out by scanning the stimulable phosphor by a stimulating ray to cause the phosphor to emit light of the amount corresponding to the radiation energy stored in the phosphor. The emitted light is detected and converted to an electric signal. The level of the electric signal is converted in such a way that the maximum level of the signal corresponding to the maximum density of the radiation image is converted to a level resulting in the optical density of 1.5 to 2.8 in the reproduced image on a recording material and the minimum level corresponding to the minimum density is converted to a level resulting in the optical density of fog density of the recording material to fog density plus 0.3, and a density curve in a coordinate having an ordinate representing the optical density and an abscissa representing the level of the electric signal has a positive gradient from the minimum level to the maximum level.

Integrated-strapdown-air-data sensor system

Abstract: A plurality of inertial measuring unit (IMU) modules (41A, B, C and D) each comprising gyros and accelerometers (61, 65 and 67) for sensing inertial information along two orthogonal axes, are strapdown mounted in an aircraft, preferably such that the sense axes of the IMUs are skewed with respect to one another. Inertial and temperature signals produced by the IMU modules, plus pressure signals produced by a plurality of pressure transducer modules (43A, B and C) and air temperature signals produced by total air temperature sensors (45A and B) are applied to redundant signal processors (47A, B and C). The signal processors convert the raw analog information signals into digital form, error compensate the incoming raw digital data and, then, manipulate the compensated digital data to produce signals suitable for use by the automatic flight control, pilot display and navigation systems of the aircraft. The signal processors include: an interface system comprising a gyro subsystem (47), an accelerometer and air calibration data subsystem (50) and an air data and temperature subsystem (52); a computer (54); an instruction decoder ( 56); and, a clock (58). During computer interrupt intervals raw digital data is fed to the computer (54) by the interface subsystems under the control of the instruction decoder (56). The computer includes a central processing unit that compensates raw digital gyro and accelerometer data to eliminate bias, scale factor, dynamic and temperature errors, as necessary. The central processing unit also modifies the gyro and accelerometer data to compensate for relative misalignment between the sense axes of the gyros and accelerometers and for the skewed orientation of these sense axes relative to the yaw, roll and pitch axes of the aircraft. Further, accelerometer data is transformed from body coordinate form to navigational coordinate form and the result used to determine the velocity and position of the aircraft. Finally, the central processing unit develops initializing alignment signals and develops altitude, speed and corrected temperature and pressure signals.

Anti-collision vehicular radar system

Abstract: A radar system mounted on a vehicle and having an RF signal transmitted preferably in a confined beam in front of the vehicle and reflected from obstacles in the path of the beam to be reflected back to the vehicle. The system includes an asymmetrical magic tee which receives both the transmitted and received signals and provides a pair of Doppler frequency signals whose relative phase relationship determines whether the signal is an opening or closing Doppler signal. The signal employs a diplex Doppler detection scheme for providing both range and rate data. Under an imminent collision situation the system provides control signals to power means for pulsating the brakes of the vehicle to thereby avoid a collision. To minimize false target detections and to provide target discrimination, there is provided in this system both a range gated circuit for detecting normal closing rates and an amplitude gated circuit that is operable primarily for detecting fast closing rates such as may occur when a vehicle is stopped in the roadway. A ground speed detector is provided and has an output analog voltage which is usable as a gain control voltage for the range and amplitude gated circuits. The system is also provided with means for inhibiting braking action below a predetermined vehicle speed for use in slow traffic, and means for altering the braking action at speeds above a predetermined speed such as on the order of 35 MPH.

High performance semiconductor package assembly

Abstract: High Performance Semiconductor Package Assembly Abstract An improved high performance semiconductor package assembly for interconnecting a plurality of integrated circuit devices having a multilayer sub-strate with internal wiring including signal wiring and external signal and power connections, a plurality of integrated circuit semiconductor devices supported on the top surface of the substrate in electrically connected operative relation, the improvement being a power supply distribution system for providing electrical supply voltages to the devices from the power connections consisting of radial waveguide structure including parallel waveguide planes with a low input impedence to reduce switching noise, the waveguide planes located between the signal fan-out wiring and internal wiring metallurgy and connected in common to all of the plurality of devices.

Portable radio frequency emitting identifier

Abstract: An automatic identification system wherein a portable identifier, preferably shaped like a credit card, incorporates an oscillator and encoder so as to generate a programmable pulse position-modulated signal in the radio frequency range for identification of the user. The identifier can be made to generate the identification signal constantly or can be made for stimulated transmission responsive to an interrogation signal. The identification signal can be preset or can be programmable by use of a programmable memory.

Method and apparatus for controlling the operation of a television signal receiver

Abstract: A method and apparatus for controlling the operation of a video recorder to enable it to record selected types of programs is disclosed. A code signal representing information with respect to the type of program is provided at the transmitter and inserted into the vertical blanking gap of the television signal. The video recorder detects and analyzes the code signal and is actuated for recording when a selected type of program is detected.

Apparatus for controlling exposure of a solid state image sensor array

Abstract: An apparatus for controlling the exposure of a solid state image sensor array monitors the semiconductor substrate current produced as charge signal accumulates during an exposure of the array to radiant energy. The exposure of the array is controlled in response to an output signal representative of the total substrate current.

Auditory subliminal message system and method

Abstract: Ambient audio signals from the customer shopping area within a store are sensed and fed to a signal processing circuit that produces a control signal which varies with variations in the amplitude of the sensed audio signals. A control circuit adjusts the amplitude of an auditory subliminal anti-shoplifting message to increase with increasing amplitudes of sensed audio signals and decrease with decreasing amplitudes of sensed audio signals. This amplitude controlled subliminal message may be mixed with background music and transmitted to the shopping area. To reduce distortion of the subliminal message, its amplitude is controlled to increase at a first rate slower than the rate of increase of the amplitude of ambient audio signals from the area. Also, the amplitude of the subliminal message is controlled to decrease at a second rate faster than the first rate with decreasing ambient audio signal amplitudes to minimize the possibility of the subliminal message becoming supraliminal upon rapid declines in ambient audio signal amplitudes in the area. A masking signal is provided with an amplitude which is also controlled in response to the amplitude of sensed ambient audio signals. This masking signal may be combined with the auditory subliminal message to provide a composite signal fed to, and controlled by, the control circuit.

Distributed signal processing system

Abstract: A distributed, fault-tolerant, self-repairable, reconfigurable signal processing system with redundant elements comprising signal processors, mass memories and input-output controllers interconnected by redundant busses forming a high reliability system. The input-output controller element has redundant busses for interconnecting multiple fault-tolerant distributed signal processing systems into a network configuration. One signal processor element in a system is initially designated as the executive and assigns processing tasks from a mass memory to the other elements or other systems. When a failure is detected, the executive verifies the failure, isolates the faulty element and reassigns the task to another spare element. If another element is not available, the executive reconfigures the system to permit degraded operation using the available elements. The executive element, itself, is fault monitored by one of the other elements which is capable of assuming the role of executive as required. The fault-tolerant and reconfiguration capabilities of the system result from a virtual addressing technique for each element, a distributed bus arbitration method and a two-level distributed operating system.

Power cutting device for terminal units of CATV system

Abstract: In a CATV system, power supplies of television sets associated with all terminal units are cut in response to an instruction contained in a down-data signal supplied by a central facility of the system. It is possible to cut the power supplies of the television sets, selectively and periodically, by incorporating address informations in the down-data signal.

Device applicable to direction finding for measuring the relative orientation of two bodies

Abstract: A magnetic coupling device in which two assemblies of three coils are attached respectively to two mechanically independent bodies and form a radiator assembly and a sensor assembly. Each assembly defines a cartesian coordinate frame and is associated with a switching circuit controlled so that the radiator coils are excited successively and separately by the same alternating-current wave and so that the sensor coils are connected separately and successively to processing circuits during each excitation stage of a radiator coil. The processing circuits comprise a synchronous demodulator, a coherent integrator and a control loop for reducing the induced signal received to zero and measuring the corresponding field component. This measurement is performed by an ancillary computer which determines the Euler angles.

Data center for remote postage meter recharging system having physically secure encrypting apparatus and employing encrypted seed number signals

Abstract: A data center for remote postage meter recharging receives resetting signal information to reset a remotely located postage meter. The remotely located postage meter has signal information stored therein for use in recharging the meter with additional postage in conjunction with a signal information received from the data center and entered into the meter. The data center includes a sealed unit for processing received resetting signal information and encrypted signal information stored at the data center outside of the sealed unit. The stored encrypted signal information at the data center is equivalent to the signal information stored in the remotely located postage meter. The sealed unit includes a decrypter for decrypting the encrypted signal information so that it may be combined with the resetting signal information to generate a signal for use in resetting the remotely located postage meter. The sealed unit also includes an encrypter for encrypting information to provide updated encrypted signal information to be stored at the data center outside of the sealed unit for use when the remotely located postage meter is again to be reset with additional postage.

System containing a predetermined number of monitoring devices and at least one central station

Abstract: The system contains a number of monitoring devices, such as bedside units for monitoring parameters of patients, and a central station in star connection. Each monitoring device contains a signal generator and a display device for the display of monitored parameters. The central station contains a central display device and a central multiplexer. The multiplexer has a separate signal input for receiving the output signals of each signal generator, and a first and second number of multiplexer outputs. The output signals of the signal generators each contain undelayed and delayed signal data. The first multiplexer outputs can be connected to the central display device. Thereby, the undelayed signal data contained in the output signals of selected monitoring devices can be displayed in the central station. These signal data represent all parameters monitored by the selected device. The second multiplexer outputs are connected to an intermediate memory for transfer of the delayed signal data of all signal generators thereto. The delayed data stored in the memory can be transmitted in any signal combination for display as a mixed image on the central display device. Thereby, parameters stemming from different monitoring devices can be displayed simultaneously on the central display device.

Radiographic systems employing multi-linear arrays of electronic radiation detectors

Abstract: A scanning radiographic system employing a multi-linear array. The system includes a source of electronic radiation, which is focused upon the multi-linear array. The multi-linear array includes radiation sensors each of which is adapted to generate an intensity signal as a function of the amount of radiation sensed thereby. Each sensor has associated therewith a means for holding or storing its respective intensity signals. The intensity signals thus held may be continually up-dated to reflect subsequent intensity signals resulting from additional radiation sensed by the respective sensors. An opaque object to be scanned by the radiographic system passes through the beam of radiation in a controlled fashion. This controlled motion is synchronized and coordinated with the shifting of the up-dated intensity signals so that the speed and course of travel of a particular up-dated intensity signal through the holding means of a given group of said sensors is optically aligned with the speed and course of travel of the radiation passing through a given area of the opaque specimen. In this fashion, there is generated one up-dated intensity signal corresponding to a given area of the opaque specimen. These up-dated intensity signals are then collected and processed by a suitable visual system.

Global position system (GPS) multiplexed receiver

Abstract: A global position system (GPS) capable of multiple (two or more space vehicles) space vehicle (SV) multiplexing comprises an RF energy receiver for receiving high and low frequencies (L 1 and L 2 ) from a plurality of SVs on different codes, a switching means for alternately switching the RF receiver between the coded L 1 , L 2 signals for detection, a digital processing means, replica coded L 1 , L 2 signal producing hardware, and a coherent time and frequency synthesis means, said digital processing means connected to the RF receiver, coherent time and frequency synthesis means, and replica coded L 1 , L 2 signal producing hardware for producing for the RF receiver replica coded L 1 , L 2 signals for each SV to be tracked and adjusting with respect to the coherent time and frequency synthesis circuit the states of the hardware replica receiver signals to align them with corresponding signals of each of the SVs at a rate that supports sampled data closed-loop tracking of the SVs without reacquisition of each SV being tracked.

Speed change control device for automatic transmission

Abstract: A shift control device for an automatic transmission is disclosed. The device comprises a vehicle speed sensor for sensing vehicle speed, an engine load sensor for sensing engine load, a shift control circuit for generating shift instruction signal based on a predetermined shift pattern in accordance with output signals from both sensors, a shift pattern decision circuit including means for generating a resulting signal obtained by arithmetically operating upon the actually measured acceleration from the output voltage of the vehicle speed sensor, a reference acceleration setting means connected to both sensors for obtaining for every shift position a reference acceleration corresponding to the output signals delivered from the vehicle speed sensor and engine load sensor, a comparator means for comparing the actually measured acceleration with the reference acceleration to change a predetermined shift pattern based on the compared result, and means for setting a hysteresis characteristic to the change of the shift pattern.

The development and applications of a wide band electromagnetic sounding system using a pseudo-noise source

Abstract: A very wide band (0.03 Hz to 15 kHz) electromagnetic (EM) system has been developed. It was used over the band 1 Hz to 10 kHz to determine the electrical structure of the earth’s crust from depths of a few meters to over 40 km. A direct current of from 1 to 5 A was reversed through a long wire bipole transmitter in a pseudo‐random binary sequence (PRBS). Depending upon the frequencies selected, a sensitive one‐component flux gate magnetometer or an air‐core coil was used to monitor temporal changes in the vertical component of the magnetic field at a recording site. The measured signal was crosscorrelated digitally in real time with an exact copy of the transmitted waveform in order to obtain a good signal‐to‐noise ratio at distances up to 5 times the length of the bipole. The output crosscorrelogram was deconvolved from the system input, the autocorrelogram of the transmitted waveform, using a Wiener least‐squares filter to give the impulse response of the earth. This was then transformed into frequency ...

Apparatus for determining the distance to a concealed conductive object which is radiating an alternating current signal

Abstract: An apparatus to measure the distance to a concealed conductive object, radiating an electromagnetic signal, has two sensors, each adapted to receive the signal and to produce an output voltage proportional to the amount of signal received. Amplifier means amplify the output voltage. Automatic gain control means automatically controls the gain to the amplifier means such that the gain of the amplification of one of the output voltages is the same as the gain of the amplification of the other output voltage. Computing means calculate the distance based upon the two amplified output voltages. Display means display the calculated value.