Abstract: An apparatus and method to characterize an input communication signal as being a voice, tone or noise signal is provided. The apparatus and method involve measuring variations of pitch over time from a sampled input signal. A minimum value of Average Magnitude Difference Function (AMDF) over a pitch range and an average variation value of the AMDF over sampled intervals are used to determine whether the signal is a voice signal, a tone or noise. Historical data of these values is maintained in a dual buffer arrangement and is used in the determination of signal type by detecting transitions.

Abstract: A frequency analyzing device for detecting a signal component of a predetermined analytic frequency to be analyzed in an input signal includes a multiplication circuit and an integration circuit. The multiplication circuit controls a switched capacitor circuit for discretely storing an input signal using a predetermined pulse signal whose frequency changes according to an amplitude of an orthogonal function system signal having the analytic frequency, and outputs charges representing a multiplication result of the input signal and the orthogonal function system signal. The integration circuit integrates the charges output from the multiplication circuit and outputs integration values as signal components of the analytic frequency contained in the input signal.

Abstract: A signal analyzer has an analysis scale and a display scale that are independently selectable. The signal analyzer receives a first representation of an applied signal and provides from the first representation at least two alternative representations. A first selective input enables a designated one of the alternative representations to be applied to a filter to reduce variance of the designated representation. The signal analyzer then converts the received one of the alternative representations having reduced variance to at least two alternative display scales. A second selective input enables a designated one of the alternative display scales to be displayed on a monitor, display screen or other output device of the measurement instrument or system.

Abstract: A time domain data converter with output frequency domain conversion. A data conversion circuit is operable to receive a signal in the time domain and provide an output in the frequency domain. It includes a data converter for converting data from an analog format to a digital format in the time domain. It also includes a processor for processing the data in the digital format output from the data converter through a time domain/frequency domain transform to provide data in the digital format in the frequency domain. The output of the frequency domain operation or the time domain operation can be provided for output in response to the generation of a data ready signal.

Abstract: A signal analysis system and method for analyzing an input signal acquired from a mechanical system. The mechanical system may include at least one rotating apparatus. The signal analysis system may be configured to: (a) receive samples of the input signal, (b) perform an invertible joint time-frequency transform (e.g. a Gabor transform) on the samples of the input signal to produce a first array of coefficients which depend on time and frequency, (c) compute an instantaneous rotation frequency signal, (d) select first coefficients from the first array which correspond to one or more order components in the input signal, i.e. one or more multiples of the instantaneous rotation frequency signal, (e) generate a time domain signal from the first coefficients, and (f) present the time domain signal to a user on a presentation device. The signal analysis system may generate the time domain signal from the first coefficients by performing an inverse joint time-frequency transform on the first coefficients.

Abstract: A power spectrum waveform is obtained by logarithmically amplifying a signal received by a frequency-sweep operation, detecting the amplified output of each frequency sweep, converting the detected output into a digital signal value in decibels, and converting this digital signal value into an antilogarithmic power value in watts for each display point within the width of the frequency sweep. Upon completion of the frequency sweep operation, the power values which have been converted into antilogarithmic values for each frequency sweep are averaged for each display point, the average power values are converted into logarithmic values, and the logarithmic values are displayed as a spectrum display.

Abstract: A signal analysis system and method for analyzing an input signal acquired from a mechanical system. The mechanical system may include at least one rotating apparatus. The signal analysis system may be configured to: (a) receive samples of the input signal, (b) perform an invertible joint time-frequency transform (e.g. a Gabor transform) on the samples of the input signal to produce a first array of coefficients which depend on time and frequency, (c) select first coefficients from the first array which correspond to a first subset of one or more order components in the input signal, (d) generate a time domain signal from the first coefficients, and (e) present the time domain signal to a user on a presentation device. The signal analysis system generate the time domain signal from the first coefficients by performing an inverse joint time-frequency transform on the first coefficients.

Abstract: An equivalent circuit and an analysis method are provided for highly accurately indicating characteristic of an inductance element wherein ferrite material is used. An equivalent circuit is used, wherein a closed circuit with resistance Rm1 and Rm2, and inductance Lm1 and Lm2 magnetically connects to inductance Ls of LsCpRp parallel circuit at coupling coefficients k1 and k2. First, the values of circuit constants Ls, Rp, and Cp are determined by making use of the conditions at the resonance point. Next, changes of reactance component in the equivalent circuit for frequency are calculated, based on the determined values of circuit constants Ls, Rp, and Cp, and find the values of frequency fm1 and fm2 whereat reactance component should be decreased by comparing frequency changes of measured reactance component.

Abstract: The invention relates to a method for forming output signals of an interference current monitor or of a state monitor of an electrical rail vehicle with current being drawn from a power grid, and optionally a current also being delivered back into said power grid, via a current collector. In the case of a state monitor, not only interference currents but also further fault states are identified and signaled. The method steps include detection by measurement and digitization of the vehicle current flowing via the current collector or of other measurement quantities which make it possible to infer vehicle states which leads to interference currents, and digital processing of these measured values with determination of the spectral density of interference currents or of interference values of the other measurement quantities, a multistage system of response thresholds being used in order to evaluate the spectral density.

Abstract: The present invention discloses an apparatus for detecting one or more fluids, the apparatus comprising a sensor means having electrical properties dependent upon one or more of the presence and the concentration of one or more fluids, an electrical excitation means for applying one or more electrical excitation pulses to the sensor means, a detector means for detecting the electrical behavior of the sensor means in response to the electrical excitation means, and a transformation means for transforming an output of the detector means from the time domain to the frequency domain to determine the electrical properties of the sensor means as a function of frequency over a pre-determined frequency range.

Abstract: A method for measuring the ripeness and the texture of a fruit, the method comprising a step for applying a vibration having sequentially hanging frequencies to a fruit to be measured, a step for measuring the intensity of the vibration applied to the fruit and the intensity of the vibration of the fruit, a step for measuring the weight of the fruit, a step for finding the transfer functional characteristic of the fruit by performing frequency analysis based on the intensity of the vibration applied to the fruit and the intensity of the vibration of the fruit, and computing the secondary resonance frequency f0 (i.e.

Abstract: A method and apparatus enabling information including respective angular directions to be obtained for one or more sound sources includes a sound source direction estimation section for frequency-domain and time-domain processing of sets of output signals from a microphone array to derive successive estimated angular directions of each of the sound sources. The estimated directions can be utilized by a passage detection section to detect when a sound source is currently moving past the microphone array and the direction of the sound source at the time point when such passage detection is achieved, and a motion velocity detection section which is triggered by such passage detection to calculate the velocity of the passing sound source by using successively obtained estimated directions.

Abstract: The present invention is a method of measuring a gonio-spectral reflectance factor to establish a gonio-spectral reflectance factor database available for a personal computer by which a highly-fine realistic 3D computer graphics image can be formed. The method enables colorimetry in a reduced hours in fewer viewing directions compared to the conventional method by executing colorimetry in a plurality of viewing directions selected at random from all the directions that can be viewed by a goniospectrophotometer, said plurality of viewing directions being less than all the directions that can be viewed by the goniospectrophotometer.

Abstract: A method and system for monitoring at least one of a system, a process and a data source. A method and system have been developed for carrying out surveillance, testing and modification of an ongoing process or other source of data, such as a spectroscopic examination. A signal from the system under surveillance is collected and compared with a reference signal, a frequency domain transformation carried out for the system signal and reference signal, a frequency domain difference function established. The process is then repeated until a full range of data is accumulated over the time domain and a SPRT sequential probability ratio test methodology applied to determine a three-dimensional surface plot characteristic of the operating state of the system under surveillance.

Abstract: A stencil generator for automatically constructing a stencil representative of signals having similar characteristics includes a boundary extractor and a component generator. The boundary extractor is operable to (i) receive a frequency spectrum of a signal, and (ii) obtain from the received frequency spectrum a plurality of characteristic frequency boundaries for the signal. The component generator is coupled to the boundary extractor and is operable to (i) receive the frequency spectrum, (ii) receive the plurality of characteristic frequency boundaries from the boundary extractor, and (iii) define a plurality of stencil components based upon the plurality of characteristic frequency boundaries and the frequency spectrum.

Abstract: A spectrum analyzer is provided with a continuous period measurement function which continuously measures time periods of each and every cycle of an IF signal to analyze changes in frequency and time period of an input signal in a time domain. The frequency spectrum analyzer having a sweep local oscillator includes a continuous period measurement block for continuously measuring each time period of an IF signal produced by mixing the input signal and the local oscillator signal, and a processor and display for processing the data representing the continuous time period produced by the continuous period measurement block to analyze the input signal in the time domain.

Abstract: A portable electronic vibration measurement device, detects a large number of structure-borne sound signals using a predetermined sequence of a plurality of specific individual measurements each plurality of measurements taken at a different sampling frequency.

Abstract: A method for removing spurious signals in a process of motor current signature analysis of an electric motor (24 or 33) includes creating an electronic model of the motor, acquiring simultaneous measurements of voltage and current at the motor, applying the voltage measurement to the motor model and determining an equivalent current produced in the motor model by the applied voltage, subtracting the equivalent current from the current measurement to produce a corrected motor current, and processing the corrected motor current through motor current signature analysis. For an ac motor (33), the method includes extracting signals corresponding to the fundamental excitation frequency from the voltage measurement to produce an interfering voltage, processing the interfering voltage through the motor model to produce a corresponding spurious current signal, and subtracting the spurious current signal from the measured current to produce the corrected motor current signal for analysis.

Abstract: A measuring device and method use a spectrum analyzer. The spectrum analyzer comprises a display screen controlled by a processor on which a spectrum of an input signal is displayed in a frequency region on a half portion of the display screen and a noise level at a frequency associated with the input signal is displayed in a time region on another half portion of the display screen.

Abstract: A high sample rate cosine filter eliminates DC components by summing them such that they sum to zero. A non-orthogonal cosine filter is also provided. When the cosine filter is applied for N=4 samples per cycle, the samples are separated by 90 degrees. However, at higher sampling rates, it is not necessary to wait for 90 degrees to estimate the phasor value. Non-orthogonal components are used to estimate the phasor value. The time delay associated with the cosine filter is reduced in the process.

Abstract: The invention relates to an improved adaptive spectral estimator for estimating the spectral components in a signal containing both an information signal, such as speech, and noise. A method and system provide for generating noise estimates and then only updating the noise estimates during pauses in an information signal, when speech or other information is not detected, rather than continuously updating the noise estimates. A noise estimate is calculated for each frequency band and provides for the inclusion of a variable mathematical factor that can be set by the user to produce the best sound quality.

Abstract: In accordance with the present invention, a method for obtaining frequency nformation about a given data set is realized. The method comprises the steps of providing a processing unit; inputting a raw data set into the processing unit; optionally removing at least one trend from the raw data; ordering the raw data; estimating power spectral density using an eigenanalysis approach and the inputted raw data and the ordered raw data; simultaneously estimating the power spectral density using the raw data and a periodogram; generating a time-series representation of the raw data to which curve fitting is applied; comparing the results from the power spectral density estimating steps and the time-series representation generating step to determine if any frequencies suggested by the eigenanalysis approach estimating step are valid; and generating an output signal representative of each valid frequency.

Abstract: A method for sensing and analyzing data with surface acoustic wave (SAW) devices comprises the steps of: propagating a sampling signal at a fundamental frequency through a SAW device coated for selective adsorption; measuring at least one parameter of at least one higher order harmonic of the fundamental frequency sampling signal; exposing the coated SAW device to enable the selective adsorption; measuring the at least one parameter of the at least one higher order harmonic of the fundamental frequency sampling signal after the exposing step; comparing the measurements of the at least one parameter of the at least one higher order harmonic before and after the exposing step; and, deriving a result of the selective adsorption based upon the comparing step. The at least one parameter is harmonic power and harmonic frequency. The at least one higher order harmonic is one or more odd harmonics.

Abstract: A method and apparatus for fast response and distortion measurement of a signal transfer device. A computer processor generates a multitone test signal of predetermined duration and stores it in a memory. The test signal is read out, converted to analog form, if necessary, and applied to the input of a device under test. The output produced by the device under test in response to the test signal is acquired and digitized, if necessary, and a Fast Fourier Transform is performed on the acquired data to determine its spectral characteristics. Frequency response, harmonic distortion, intermodulation distortion, phase distortion, wow and flutter and other signal transfer characteristics are measured by the CPU by analysis of the output signal.

Abstract: Optical Doppler tomography permits imaging of fluid flow velocity in highly scattering media. The tomography system combines Doppler velocimetry with high spatial resolution of partially coherent optical interferometry to measure fluid flow velocity at discrete spatial locations. Noninvasive in vivo imaging of blood flow dynamics and tissue structures with high spatial resolutions of the order of 2 to 10 microns is achieved in biological systems. The backscattered interference signals derived from the interferometer may be analyzed either through power spectrum determination to obtain the position and velocity of each particle in the fluid flow sample at each pixel, or the interference spectral density may be analyzed at each frequency in the spectrum to obtain the positions and velocities of the particles in a cross-section to which the interference spectral density corresponds.

Abstract: A frequency analyzing method according to the invention is a method of analyzing frequency components of an original signal. The method has: a spectrum detecting step of detecting, from the original signal, energy levels of components of a predetermined number of orthogonal function waves which have waveforms each having same start position and end position in a predetermined time window and in which the number of occurrences of periods in the predetermined time window or frequencies are different from each other; and an orthogonal function wave changing step of changing at least one of the start position and the end position within the predetermined time window after completion of the spectrum detecting step, wherein the spectrum detecting step and the orthogonal function wave changing step are alternately repeated.

Abstract: The invention detects the loft time and/or speed of a vehicle, such as a sporting vehicle, during activities of moving and jumping. A loft sensor detects when the vehicle leaves the ground and when the vehicle returns to the ground. A microprocessor subsystem converts the sensed information to determine a loft time. A display shows the recorded loft time to a user of the system. In addition, a speed sensor can detect the vehicle's speed for selective display to the user. The invention is particularly well-suited to sporting activities such as snowboarding where users loft into the air on ski jumps and catch "air" time but have no quantitative measure of the actual time lapse in the air. Therefore, users in skiing can use invention to record, store, and playback selected information relating to their sporting day, including the total amount of "air" time for the day and information such as dead time, i.e., time not spent on the slopes.

Abstract: The tension in an optical fiber being drawn from a preform is monitored by sensing its motion transverse to the drawing direction and analysing the sensed motion using an autoregressive time-series model to provide a power spectrum. One of the peaks of the spectrum is identified as associated with the fundamental natural frequency of the drawn fiber and the frequency of that peak is used in a calculation of the tension of the fiber.

Abstract: A stereophonic image may be enhanced by splitting the left and right input audio signals into a plurality of left and right output signals in a plurality of audio frequency bands and then generating left and right output audio signals from the left and right output signals based on the magnitude of the differences between corresponding left and right output signals and also based upon the absolute magnitude of the left and right input audio signals themselves. In particular, a stereophonic image enhancement device according to the invention processes a left input signal and a right input signal using a first spectrum analyzer and a second spectrum analyzer which output a plurality of left output signals and right output signals corresponding to a plurality of frequency bands in response to the corresponding left input signal and right input signal.

Abstract: A method and apparatus for sampling an analog signal permits the identification of those samples in which data was lost in the sampling process. A data reference element is generated for each sample element, the data reference element having a corresponding sample element. A user friendly display technique is provided to permit the user to controllably display the sampled signal, clearly showing those portions of the signal in which information was lost contrasted with those portions of the signal that were sampled intact.

Abstract: The operational condition of a machine is evaluated when the machine's vibration spectrum deviates from an acceptable state, where an acceptable state is defined by an alarm limit envelope. The amplitude of individual peaks within the machine's vibration spectrum is compared to the alarm limit envelope, and a deviation severity value characterizing the severity of the machine's deviation from an acceptable state is determined for each deviating peak. The deviation severity value represents the severity of deviation when at least one individual peak within the machine's vibration spectrum exceeds the alarm limit envelope. The deviation severity value is obtained by determining the peak excess magnitude for each vibration peak, where the peak excess magnitude is the amount by which the amplitude of each deviating vibration peak exceeds the alarm limit envelope level. The peak excess magnitude is then normalized by a frequency-dependent normalization factor.

Abstract: An iterative time frequency algorithm filters noisy wide band/nonstationary signals by projecting the noisy signal into the TF domain, masking the TF response, computing the inverse TF transform to extract a filtered signal, and repeating these steps until the projection lies within the mask. As a result, the TF domain properties of the extracted signal are substantially equal to the desired TF domain properties. Furthermore, the iterative approach is computationally simple because it avoids inverting matrices. The TF transform and its inverse must be selected such that the iterative algorithm is guaranteed to converge. Candidate transform pairs can be tested on known data, and if the TF transforms converge to the desired TF properties, the candidate pair can be selected. Alternately, the candidate pairs can be tested against a sufficient convergence condition, and if they satisfy the condition within an acceptable tolerance, they can be selected with confidence.

Abstract: A new method of compensating for errors in phasor estimation due to oscillations caused by discrete fourier transforms used to estimate signal frequency is provided. The method uses a variable N-point DFT to compute one or more phasors based on data acquired from one or more sampled signals. At each sampling interval the change in phasor angle between the current sampling interval and the previous sampling interval is determined and used to estimate the instantaneous frequency of the signal. A non-oscillating phasor indicative of the instantaneous magnitude, angular frequency, and phase angle of the signal is generated based on the instantaneous frequency estimate. Instantaneous frequencies are averaged over a cycle of the signal to generate an average cycle frequency. In addition, a number of discrete frequencies and corresponding DFT windows based on a fixed sampling rate and a predetermined fundamental frequency of the signal are defined and used in estimating the instantaneous frequency.

Abstract: A method for estimating phasors and tracking the frequency of a signal during frequency ramping is provided. The method uses a variable N-point DFT periodically to compute one or more phasors based on data acquired from one or more sampled signals. The period between DFT computations is a predetermined number of sample periods. After each DFT computation, the change in phasor angle between the current phasor estimate and the most previous phasor estimate is determined and used to estimate the instantaneous frequency of the signal. The current instantaneous frequency estimate and the most previous instantaneous frequency estimate are averaged to compute an average cycle frequency. In addition, a number of discrete frequencies and corresponding DFT windows based on a fixed sampling rate and a predetermined fundamental frequency of the signal are defined and used in estimating the instantaneous frequency.