Abstract: A method and system for generating a noise index for a mechanical system in which noise data is acquired over a predetermined frequency range. A fundamental harmonic frequency is chosen and this fundamental harmonic frequency is used to mark harmonic and sub-harmonic data bins. The amplitude of the harmonic and sub-harmonic data bins are recorded and a plurality of sub-harmonic bins equally offset from the center of each harmonic frequency are averaged and the average is subtracted from the preceding harmonic level. The result is accumulated as harmonic content levels to generate a harmonic index number.

Abstract: This method removes high frequency noise from shape data, significantly improves metrology system (10) performance and provides very compact representation of the shape. This model-based method for wafer shape reconstruction from data measured by a dimensional metrology system (10) is best accomplished using the set of Zernike polynomials (matrix L). The method is based on decomposition of the wafer shape over the complete set of the spatial function. A weighted least squares fit is used to provide the best linear estimates of the decomposition coefficients (Bnk). The method is operable with data that is not taken at regular data points and generates a reduced data field of Zernike coefficients compared to the large size of the original data field.

Abstract: There is presented a reliable technique for measuring condition change in nonlinear data such as brain waves. The nonlinear data is filtered and discretized into windowed data sets. The system dynamics within each data set is represented by a sequence of connected phase-space points, and for each data set a distribution function is derived. New metrics are introduced that evaluate the distance between distribution functions. The metrics are properly renormalized to provide robust and sensitive relative measures of condition change. As an example, these measures can be used on EEG data, to provide timely discrimination between normal, preseizure, seizure, and post-seizure states in epileptic patients. Apparatus utilizing hardware or software to perform the method and provide an indicative output is also disclosed.

Abstract: The invention encompasses a vortex flowmeter for measuring the flow rate of a fluid by detecting an alternating signal produced by Karman vortices using a sensor comprising a low pass filter for passing the frequency band of the alternating signal that is determined by the diameter and flow rate range of the vortex flowmeter; subband filters for splitting the frequency band passing through the low pass filter into a plurality of component bands; a spectrum analyzer for analyzing the plurality of component bands; and a bandpass filter for passing a frequency band to be measured according to the analysis results of the spectrum analyzer, thereby providing flow rate measurement with high precision.

Abstract: A magnetic field measuring apparatus for precise cancellation of environmental noise includes a plurality of first SQUID gradiometers to detect noise and biomagnetic fields, a plurality of second SQUID gradiometers to detect noise, a driving circuit to drive these gradiometers, and a computer to execute signal processing after collecting the signals detected by these gradiometers. First and second SQUID gradiometers are provided which include first-order gradient pickup coils with the baselines formed by the coils of second gradiometers being shorter than those of first gradiometers. The apparatus cancels noise, from detected biomagnetic signal waveforms, caused by variant noise cancellation rates of the coils of first gradiometers, different baselines of the coils of second gradiometers, and the frequency property of a magnetically shielded room in which the apparatus is installed.

Abstract: A method of processing data representing intensity values of a measurement signal as a function of a discrete variable such as time, which signal being characterized by series of peaks mixed with a substantially regular background noise, provides efficient noise attenuation and peak detection capabilities. When applied to a two-dimensional system, the method comprises an initial step of forming an intensity histogram vector representing a frequency distribution from the intensity values, which intensity histogram vector having N frequency vector components associated with corresponding N intensity sub-ranges within a maximum range extending from a minimum intensity value to a maximum intensity value. This initial step is followed by a step of zeroing a portion of the data corresponding to the intensity values which are below an intensity threshold value derived from shape characteristics of the distribution.

Abstract: A method and apparatus for allocating decoupling capacitance in a power grid is provided. A power grid model of an RLC network is evaluated to identify the power nodes that have peak voltages exceeding a minimum voltage threshold and a maximum voltage threshold. For each noisy node that violates the thresholds, a decoupling capacitor is inserted. The power grid is once again re-evaluated to determine of any of the power nodes still violate the voltage thresholds. For those violating power nodes, the size of the decoupling capacitor is incremented. This process of incrementing the size of the decoupling capacitance and re-evaluating the power grid is repeated until all the power nodes are within a noise budget or the noise level for each power node is within the thresholds. The decoupling capacitance is then re-evaluated as it is iteratively decremented while maintaining the power noise within the thresholds.

Abstract: A process for the denoising of audio signals picked up in a noisy environment, for example in the cockpit of an aircraft or of another vehicle, and more precisely to the searching for a noise model in the audio signals. Input signals are digitized, and these signals are processed on the basis of a noise model, in principle with a view to eliminate as far as possible the noise corresponding to the model.

Abstract: The present invention provides a method and an apparatus for measuring a light absorption spectra which can remove a noise included in a measurement signal, and achieve a high sensitivity of a laser spectral in a good S/N ratio. According to the present invention, there is provided a method for measuring a light absorption spectra comprising the steps of: (i) conducting a Fourier transform of an absorption spectra measured by using a laser beam source; (ii) disassembling in a Fourier space the Fourier transformed signal into a signal resulted from a periodic vibration component and a signal resulted from a molecular absorption spectra; (iii) removing the Fourier component resulted from said periodic vibration component in a Fourier space; and (iv) conducting an inverse Fourier transform on the signal from which said periodic vibration component is removed, whereby reproducing an absorption spectra in a real space.

Abstract: A data processing apparatus for processing input data and for outputting the processed data as output data achieves effective noise reduction. An input-reliability calculator calculates an input reliability indicating the reliability of the input data. An output-reliability calculator calculates an output reliability indicating the reliability of the output data. A correction-value calculator calculates a correction value for correcting the input reliability. A data processing unit processes the input data based on the input reliability corrected with the correction value and the output reliability, thereby obtaining the output data.

Abstract: A signal processor generates an estimate of a block of weighted input values. An adjustable mode parameter determines a time point relative to the input values at which the estimate is computed. By varying the mode parameter, the output characteristics of the processor are variable between that of a smoother, a filter and a forward predictor of the input values. When input signal confidence is low, the mode parameter is adjusted so that the processor smoothes the input signal. When input signal confidence is high, the mode parameter is adjusted so that the processor output has a faster and more accurate response to the input signal. The variable mode averager is particular applicable to the monitoring of critical physiological parameters in patient-care settings.

Abstract: A method and system for detecting a coherent signal of unknown frequency from an incoming electrical signal comprising a multiplicity of frequencies is disclosed. A time sequence of sample data signals generated from the incoming electrical signal is decomposed into a plurality of frequency range signals using wavelet functions. The coherent signal is detected in the time sequence based on the frequency range signals. In one embodiment, a program gate array is used to process the time sequence of data samples using wavelet functions. In another embodiment, the data samples are decomposed using Haar scaling and wavelet functions to form smoothed and detailed components of the frequency range signals. The frequency range signals may be compared to at least one predetermined threshold signal to detect the coherent signal in the time sequence of sample data signals.

Abstract: An adaptive forward error correction technique based on noise bursts and the rate at which they occur is disclosed. The forward error correction parameters are determined using statistics describing the noise burst duration and period. The occurrence, duration and period of the noise burst are determined by the error vector magnitude calculated during the decoding process.

Abstract: A fuzzy logic based model assessment system assesses models of physical phenomena and in one example, is used for contact tracking. The system uses measurement residual values representing the difference between a measured data sequence corresponding to the physical phenomena and an expected data sequence corresponding to the model to be assessed. The system includes a feature identification module for identifying one or more features or tracking anomalies in the measurement residual values, such as jump and drift, and for generating feature amplitude values and feature amplitude standard deviation values. An anomaly characterization module characterizes the features in one or more membership classes representing the strength of the identified feature and generates class membership intervals representing a range of degrees of membership in each of the classes (e.g., null, weak, moderate or strong).

Abstract: A time series that is established by a measured signal of a dynamic system, for example a quotation curve on the stock market, is modelled according to its probability density in order to be able to make a prediction of future values. A non-linear Markov process of the order m is suited for describing the conditioned probability densities. A neural network is trained according to the probabilities of the Markov process using the maximum likelihood principle, which is a training rule for maximizing the product of probabilities. The neural network predicts a value in the future for a prescribable number of values m from the past of the signal to be predicted. A number of steps in the future can be predicted by iteration. The order m of the non-linear Markov process, which corresponds to the number of values from the past that are important in the modelling of the conditioned probability densities, serves as parameter for improving the probability of the prediction.

Abstract: The reproduction sound level of high priority messages such as navigation instructions, parking aid signals, and back-up warning signals is controlled based on the average ambient sound level in a vehicle. A sound level calibration table provides priority gain values for setting the programmable gain of a gain controller to ensure that messages are reproduced at a sound level which is relatively greater than ambient noise level by a predetermined target difference which is consistent for all levels of ambient noise. The target difference may be modified according to user preferences.

Abstract: A CPU of an effector calculates envelopes of an impulse response waveform from sample data of impulse response waveform data supplied from a microphone via an A/D converter circuit. Next, CPU detects a section during which a slope of the detected envelopes takes a value near “0” during a predetermined time or longer. CPU calculates an average value of sample data during the detected section to correct a DC offset. Thereafter, CPU acquires a maximum value of absolute values among the sample data during the detected section, and determines this maximum value as a background noise component value. The background noise components are removed from each sample data constituting the impulse response waveform data.

Abstract: The present invention provides a method and apparatus for eliminating or reducing local area and broad area interference in a twisted pair transmission system. The apparatus of the present invention comprises a detection device, such as an antenna, for example, for detecting electromagnetic interference coupled into a twisted pair line, a sampling/scaling device which samples and scales the detected signal, and a combiner device which combines a signal correction component with the signal received over the twisted pair by a differential receiver. The sampling/scaling device preferably comprises an analog-to-digital converter (ADC) which converts the detected analog signal into a digital signal and a digital signal processor which receives the digital signal from the ADC and processes the signal to generate a correction signal. The correction signal is then subtracted from the signal received by the differential receiver. The sampling/scaling device may be fixed or adaptive.

Abstract: The present invention is generally directed to a system and method for approximating the coupling cross- a node in a circuit and determining whether the coupling voltage noise exceeds a permissible value. In accordance with one aspect of the invention, a method uses a first circuit model to obtain a total resistance value of a conductor extending between a driver configured to drive the node and a receiver, and uses a second circuit model to determine a total capacitance. The method also determines an aggressor coupling capacitance between the node and an aggressor signal using at least one criteria, and computes a ground capacitance by subtracting the aggressor coupling capacitance from the total capacitance. The method also determines the effective resistance of the driver, and a weighted average rise time for all aggressor signals on the node.

Abstract: A method for characterizing the level of noise generated by a tire having a specific footprint configuration through analyzing the shape of the tire's footprint and taking into account the tire's aspect ratio. The method includes: a) measuring the noise level if the solution to the calculation is inside of a predetermined range; or b) reconfiguring the footprint if the solution to the calculation is outside of a predetermined range. The advantage of this method is that a tire designer can design a tire, taking into account the noise level.

Abstract: A method and apparatus for processing a composite acoustic signal to reconstruct an acoustic signal that substantially matches a selected one of a plurality of sources. A plurality of microphones positioned at different spatial locations detect. variations in sound pressure level resulting from the activity of a plurality of acoustic sources at different locations. The outputs of the microphones are sampled and digitized, and the resulting digital waveform from each microphone is provided as an input to a corresponding filter bank. The outputs of the filter banks are input to a comparison unit. A comparison control unit generates “signature” information that characterizes each source with respect to the microphones. The comparison unit receives “signature” information of a selected source from the comparison control unit and provides an output to a synthesizer unit which produces a synthesized digital waveform for the selected source.

Abstract: A method of estimating phase noise spectral density from a jitter versus time vector array obtained from a periodic signal having an average frequency includes the an initial step of converting the jitter verus time vector array to a phase error versus time vector array using an estimate of the average frequency of the periodic signal. A time to frequency transform is applied to the phase error versus time vector array to generate a phase error magnitude versus frequency vector array, and a phase noise spectral density vector array obtained by normalizing the phase error magnitude versus time vector array to a one hertz bandwidth.

Abstract: The system and method for calibrating a signal detection threshold circuit is used in a radio frequency (RF) receiver, such as a in an early warning radar (EWR) system, in which a signal detection threshold circuit rejects signals below a predetermined threshold setting and prevents noise signals from causing false alarms. The system and method include setting an initial threshold setting and receiving noise signals in one or more channels. A threshold comparison circuit rejects noise signals below the threshold setting, and a pulse repetition frequency (PRF) detection circuit detects noise pulses above the threshold setting and determines the PRF. An automatic threshold determiner and setter determines whether the PRF has reached a predetermined frequency (e.g., 400 kHz) and lowers the threshold setting until the predetermined frequency is reached. When the predetermined frequency is reached the threshold setting is stored as a noise measurement.

Abstract: A peak detecting section 121 detects the maximum values (peaks) of frequency distributions, at intervals of unit times, from the wavelet intensity signal output from an intensity computing section 113. More specifically, giving attention to frequency distributions of the wavelet intensity signal as the transform result obtained by a signal converting section 110 at predetermined time intervals, the peak detecting section 121 detects the peaks (maximum values) of the frequency intensity distributions at intervals of unit times (predetermined time intervals). Changes in various frequency features over time which are contained in the time-series signal obtained by a wavelet transform of the time-series signal can be quantitatively grasped more accurately.

Abstract: A system, and method of operating the system, for measuring a continuous signal, having at least two transducers for measuring the continuous signal and for each outputting a signal relating to the measured signal. The transducers receive controlling signals and operate in accordance therewith, the controlling signals being transmitted to the transducers along the same transmitting path consisting of no more than two electrical conductors or no more than one optical conductor or consisting of transmitters and receivers for wireless communication. Alternatively or optionally, the signal generator may receive power over two electrical conductors over which the signals are transmitted from the signal generator. The present system is especially useful in audio or in setups performing determination and analysis of vibration, acceleration, velocity or sound.

Abstract: Intermodulation distortion (IMD), especially in the form of adjacent-channel power ratio (ACPR), is an important specification for cellular base stations, especially for the power amplifier. Suppliers must demonstrate that they meet these specifications. The specifications for some of the newer communications formats, such as some forms of wideband CDMA and for multi-carrier base stations, dictate levels of ACP that seriously challenge the ability of test equipment to perform the measurement. Similar considerations apply to measuring other parameters that quantize intermodulation distortion effects, including multi-tone methods and noise power ratio. The present invention provides a technique for measuring ACP and other forms of IMD of amplifiers and other two -port devices. The technique, which uses standard equipment, enhances the normal dynamic range of measurement by at least 25 dB.

Abstract: A method of detecting tampering with an integrated circuit using circuit paths extending in the integrated circuit and carrying signals which are compared to each other, and to thresholds, and providing an output signal in the event that predetermined signal conditions occur. The predetermined signal conditions which occur may be a change of state of an output of a gate which interconnects the two circuit paths, or a change of state of the output of testing circuitry which tests signals in at least one of the circuit paths against a threshold. In a further aspect the invention concerns an integrated circuit chip provided with tamper detecting circuitry.

Abstract: A process for the identification and/or separation of composite signal into its deterministic and noisy components wherein the process uses recursive wavelet transformations to separate the deterministic and noisy components of signals and uses the difference in the properties with regard to degree of correlation and dimensionality of these constituent components as a basis for separation, the said process of identification and/or separation has application in a variety of situations where digitized data is made available via an apparatus which converts the monitored signals.

Abstract: A 1/f noise coefficient characteristic with respect to an operating point of a semiconductor device is measured, and a control voltage corresponding to an operating point of the semiconductor device with which the 1/f noise coefficient is minimized is applied to a MOSFET. Further, using a MOSFET which has known element dimensions, a relationship of a 1/f noise coefficient to a channel area is calculated, and the resistance value of the MOSFET is calculated using the channel width and the channel length as well as a constant peculiar to the MOSFET. Then, the 1/f noise coefficient of the semiconductor device is calculated using the 1/f noise coefficient with respect to the channel area of the MOSFET and the resistance value, and the channel width and the channel length of the MOSFET are set so that the 1/f noise coefficient of the semiconductor device may be minimized.

Abstract: A system and method which establishes an optimum margin for each channel in a discrete multi-tone (DMT) transceiver. The present system entails a discrete multi-tone transceiver which comprises a processor and a memory. Stored on the memory is operating logic which directs the function of the processor. The operating logic includes bit allocation logic and signal-to-noise (SNR) variation logic. The SNR variation logic determines an variation in the signal-to-noise ratio for each channel. The bit loading logic then determines a bit loading configuration based upon the variation in the signal-to-noise ratio ascertained by the SNR variation logic. The SNR variation logic preferably includes logic to determine the variation in the signal-to-noise ratio by means of statistical analysis, however, other approaches to determining the variation in the signal-to-noise ratio may be employed.

Abstract: An improved multi-antenna receiver is realized for detecting signals transmitted by a multi-antenna transmitter by summing signals received at the plurality of receiver antennas after multiplying each by a respective constant. The summed signal is applied to a maximum likelihood detector. The respective constants, &lgr;j, where j is an index designating a particular receiver antenna, are determined by evaluating the largest eigenvector of the matrix A, where &Lgr; is a vector containing the values &lgr;j, and A is a matrix containing elements &agr;ij, which is the transfer function between the ith transmitter antenna to the jth receiver antenna. The &agr;ij terms are determined in the receiver in conventional ways.

Abstract: A nonlinear analysis for characterizing phase noise and timing jitter in oscillators is disclosed. The method and apparatus utilize a nonlinear differential equation to characterize the phase error of a given oscillator. A precise stochastic characterization of timing jitter and spectral dispersion is also disclosed based on the nonlinear differential equation. Representative time and frequency domain computational techniques are disclosed for characterizing the phase noise and timing jitter of circuits. In addition, a single scalar constant, c, is utilized to describe jitter and spectral spreading in a noisy oscillator.

Abstract: A method and system for automatically establishing operational parameters of a statistical surveillance system. The method and system performs a frequency domain transition on time dependent data, a first Fourier composite is formed, serial correlation is removed, a series of Gaussian whiteness tests are performed along with an autocorrelation test, Fourier coefficients are stored and a second Fourier composite is formed. Pseudorandom noise is added, a Monte Carlo simulation is performed to establish SPRT missed alarm probabilities and tested with a synthesized signal. A false alarm test is then emperically evaluated and if less than a desired target value, then SPRT probabilities are used for performing surveillance.

Abstract: A computer implemented information extraction process that locates and identifies eddy current signal features in digital point-ordered signals, signals representing data from inspection of test materials, by enhancing the signal features relative to signal noise, detecting features of the signals, verifying the location of the signal features that can be known in advance, and outputting information about the identity and location of all detected signal features.

Abstract: A technique for estimating the harmonic content of a tread pattern design and specifically a tire pitch sequence. Pitch sequence harmonic content is obtained and analyzed as a function of position along the sequence, i.e., along the circumference of the tire tread. This localized harmonic content information may be used to assess the noise performance of a particular tire tread and further may be used as a criteria for selecting an optimal tire tread pitch sequence along with other performance criteria such as traction, tread wear, etc.

Abstract: A method, apparatus, and article of manufacture for enhanced integration of signals, such as those generated by chromatographs. In one embodiment an approximate baseline used for integration of a signal is improved to reduce error. Alternate embodiments filter drift, noise, or both from a signal prior to integration or simulated distillation. The signals are processed according to a computer program stored in a memory. The methods include steps for subtracting an approximate baseline from the signal, defining a noise band in the resulting difference, and forming a composite baseline by substituting signal data for baseline data wherever the difference does not exceed the threshold, thus leaving the parts of the approximate baseline that correspond to signal peaks unchanged.

Abstract: A signal processor (10) receives both open and closed field values for elements of a detector (11) and corrects for non-uniformities in offset response between the elements prior to converting the signal via an A to D converter (15). The corrected signal is then digitally processed to compensate for linear and higher order non-uniformities in the response of the element. The invention enables the A to D converter to have relatively low resolution for a given output radiation.

Abstract: A method and apparatus are described for fusing a plurality of signals, corresponding to mean and covariance estimates, into a single signal when the given signal estimates are correlated to an unknown degree. The core components of the method and apparatus are (1) capability to express the means and covariances of the set of signals in inverse form in a common coordinate frame and (2) capability to form a signal determined by a convex combination of the means and covariances, so expressed. The set of estimates to be fused may comprise previously fused estimates as well as measurements of a physical system. The signal derived from the fused result can be transmitted and used to physically respond to the measured state of the system of interest.

Abstract: A method and an apparatus to analyze two measured signals that are modeled as containing desired and undesired portions such as noise, FM and AM modulation. Coefficients relate the two signals according to a model defined in accordance with the present invention. In one embodiment, a transformation is used to evaluate a ratio of the two measured signals in order to find appropriate coefficients. The measured signals are then fed into a signal scrubber which uses the coefficients to remove the unwanted portions. The signal scrubbing is performed in either the time domain or in the frequency domain. The method and apparatus are particularly advantageous to blood oximetry and pulserate measurements. In another embodiment, an estimate of the pulserate is obtained by applying a set of rules to a spectral transform of the scrubbed signal. In another embodiment, an estimate of the pulserate is obtained by transforming the scrubbed signal from a first spectral domain into a second spectral domain.

Abstract: This invention pertains generally to a method for improving the accuracy of particle analysis under conditions of discrete particle loading and particularly to a method for improving signal-to-noise ratio and instrument response in laser spark spectroscopic analysis of particulate emissions. Under conditions of low particle density loading (particles/m.sup.3) resulting from low overall metal concentrations and/or large particle size uniform sampling can not be guaranteed. The present invention discloses a technique for separating laser sparks that arise from sample particles from those that do not; that is, a process for systematically "gating" the instrument response arising from "sampled" particles from those responses which do not, is dislosed as a solution to his problem. The disclosed approach is based on random sampling combined with a conditional analysis of each pulse. A threshold value is determined for the ratio of the intensity of a spectral line for a given element to a baseline region.

Abstract: A signal processing method for use in echo-location systems (radar, sonar, laser radar) to obtain accurate estimates of the target reflectivity sequence in a random (non-Gaussian) noise environment, including ambient noise, reverberation, and clutter. The method derives the statistical characteristics of the random background environments and then constructs and maximizes the corresponding approximate likelihood function using iterative methods. The approximate maximum likelihood estimates are generated on the basis of an approximation of the ideal likelihood function which is maximized using computationally efficient algorithms.

Abstract: A digital data processing circuit has an inverting circuit for inverting a positive/negative sign of the output data of an encoding circuit. A correcting circuit returns the inverted sign of the data to an original sign of data after decoding. Offset is made for truncation noises caused by the respective filtering operations in the encoding circuit and said decoding circuit. Sound quality is suppressed from degrading without increasing the circuit scale.

Abstract: Digital filters are used to compensate for echoes in a transmission system in which unwanted couplings occur between a signal value in the receiving direction and a signal value in the transmitting direction. The correct adjustment of the filter coefficients has a considerable influence on the achievable echo compensation. Disturbance signals such as background noises, nonlinear effects in A/D converters or an active local speaker can briefly change the adjustment of the filter coefficients in a way so that the digital filter does not compensate for the echoes and causes additional echoes in unfavorable cases. In accordance with the invention a set of filter coefficients (C(j)) are weighted with an envelope curve (H(j)) and an error measurement (F(j)) is determined therefrom. Depending on the magnitude of the error measurement (F(j)), the filter coefficients (ci) are used for further processing or are discarded.

Abstract: A method is described for detecting weak signals in a non-Gaussian and non-stationary background using a hidden Markov parameter estimator. The method comprises the steps of: a) partitioning input data into sets of range bins, where the input data has a noise component; b) estimating hidden Markov model parameters from the input data; c) determining the average intensity I.sub.i of the range bins, where i represents an index for the ranges bins, and 1.ltoreq.i .ltoreq.R, and R represents the total number of range bins; d) estimating the average noise intensity N.sub.i of each range bin; e) determining the residual intensity estimates .rho..sub.i of each range bin as the maximum of 0 and (I.sub.i -N.sub.

Abstract: Described are a vibration actively reducing apparatus and a method for identifying a transfer function in the vibration actively reducing apparatus. An identification signal which is a quantization of at least one sinusoidal wave is supplied from a controller of the vibration actively reducing apparatus to a controlled vibration source in synchronization with a predetermined output sampling clock (SCo) to develop an identification vibration therefrom. The controller reads a residual vibration signal from a residual vibration detector of the actively reducing apparatus in synchronization with a predetermined input sampling clock (SCi). After read of the residual vibration signal as a time series data for each frequency, an FFT calculation is carried out for each time series data to extract a frequency component of the original sinusoidal wave.

Abstract: The sensor fault detector is one in which each sensor signal is compared with a reference signal provided by e.g. a model of the system being monitored. Prior art sensor fault detectors subtract the output of the sensor and the corresponding reference signal from each other, and a fault is declared when the residual difference exceeds a prescribed threshold. However, modelling errors (such as scaling discrepancies), d.c bias and noise mean that faults are often wrongly declared, or alternatively that only large faults can be detected. These problems are overcome according to the invention by comparing the "shape" of the sensor signal with that of the corresponding reference signal (i.e. comparing the signal outlines) over a finite time window, using e.g. correlation techniques. A fault is declared when the shapes differ by a prescribed amount.

Abstract: A method for determining instantaneous helical axis parameters pertaining to the kinematic function of a joint processes the data with a first filter function which is based upon the Woltring IHA filter function. In accordance with the invention, backward propagating noise is eliminated by prefiltering the data utilizing a Butterworth filter.

Abstract: A method employed in a condition monitoring unit (CMU) for monitoring a circuit breaker or interrupter to obtain a substantially undistorted version of a waveform suffering from saturation distortion comprises employing a current transformer (CT) to measure a current waveform. The output of the CT is prone to be a partially distorted waveform. The invention is generic in the sense that it does not require parameters associated with the CT characteristics or with the burden impedance on the secondary side of the CT. A digital representation of the partially distorted waveform is obtained, and then undistorted portions of the partially distorted waveform are identified by comparing the amplitude of the partially distorted waveform within a sliding window to a pair of boundary values and identifying as undistorted those portions having an amplitude between the boundary values. Next, distorted portions of the waveform are separated from the undistorted portions, thereby yielding a data record with holes.

Abstract: A system involving method and apparatus for cancelling a periodic electrical interference signal from a signal of interest is disclosed. The system of the invention creates an estimate of the periodic noise component in an electrical signal by sampling the electrical signal at intervals locked to the period of the source of the electrical interference signal. The system analyzes the sampled signal to isolate periodically repeating portions of the signal characteristic of noise. The system inverts the estimate of the noise component and constructs a continuous repeating waveform which is added to the electrical signal. The system does not eliminate transient features of the signal of interest, even when those transient features have frequency components which overlap with frequencies present in the electrical interference signal.

Abstract: A software-based resolver-to-digital converter (RDC) (80) for computing an angle of rotation &THgr; of gimbal-mounted instrumentation (16) in a gimbal system. The RDC (80) computes the angle of rotation of the instrumentation using parameter signals received from a resolver (32) in the system. The parameter signals, along with a resolver reference signal are input into a multiplexor (60) and are multiplexed. The signals are then fed to an analog to digital converter (38) and converted to digital form. The digital signals are then input into a processor (36) associated with the system. This processor, in addition to performing numerous system computations, is programmed through appropriate software to filter the digital signals received, compute the value for the angle of rotation &THgr; and output the computed value to system circuitry (31) for processing to enhance system operation.