Abstract: A process of modeling a diffracting structure with normally incident radiation and the radiation diffracted from the structure includes constructing an optical model of the diffracting structure and calculating spectral information for the optical model based on a plurality of diffracted orders using either the positive or negative of each of said plurality of diffracted orders and the zero order. The process may be used to measure a diffracting structure, in which spectral information from a diffraction structure is extracted and compared to the calculated extracted information. The optical model is adjusted and the spectral information recalculated until an adequate fit is found, at which time it is known that the optical model accurately describes the actual diffraction grating. The process may be used with any normally incident metrology device, such as a reflectometer, ellipsometer and scatterometer.

Abstract: A method for identifying a signal source in a predetermined space, the method including inventorying a set of identified signatures corresponding to a plurality of signal sources and recording a signal simultaneously at different locations of the predetermined space. Parameters related to the conditions under which the recordings are made are then stored, and a spectrum of the signal is determined. The method also includes detecting a line emerging from background noise of the spectrum by using a predetermined emergence threshold. The line is then compared with some or all of the signatures included in the set of identified signatures, and at least one signature corresponding to the line is selected to create at least one signature/line pair. Finally, a source of the signal is identified based on the selecting step.

Abstract: A measuring apparatus includes a spectrum analysis unit having an input for receiving an input signal to be measured. The input signal includes a carrier signal located within a predetermined band of frequencies and the spectrum analysis unit is arranged to store a set of user definable parameters including the location of the carrier signal within the predetermined band of frequencies, and to use the set of user definable parameters to measure a quantity associated with the carrier signal.

Abstract: An improved method for detecting the presence of humans or animals concealed within in a vehicle uses a combination of the continuous wavelet transform and a ratio-based energy calculation to determine whether the motion detected using seismic sensors placed on the vehicle is due to the presence of a heartbeat within the vehicle or is the result of motion caused by external factors such as the wind. The method performs well in the presence of light to moderate ambient wind levels, producing far fewer false alarm indications. The new method significantly improves the range of ambient environmental conditions under which human presence detection systems can reliably operate.

Abstract: The present invention provides an erythema meter comprising a light guide that carries light of two specific wavelengths (probing and reference) at two distinct frequencies that are generated and modulated by a either a single or multiple source(s), a photodetector mounted in the tip of the guide that receives light reflected from the surface being examined, and circuitry electrically coupled to the guide for processing the light data, and determining the level of erythema present on the examined surface. The probing and reference wavelengths are delivered in sinusoidal or amplitude modulated fashion, thereby permitting electronic filtering of the received data. A calculating circuit determines the quotient of the two wavelengths after having been reflected off of a surface, such as mucosal or dermal surfaces, which is representative of the severity of erythema present in the surface.

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: A frequency margin testing blade is adapted for use in a bladed server. The testing blade is further adapted to provide one or more output clock signals for use as clock inputs to one or more server blades internal to the bladed server in which the testing blade is installed and/or one or more server blades external to the bladed server in which the testing blade is installed.

Abstract: A method and apparatus for the characterization of optical pulses and modulators includes modulating, using a modulator, a train of optical pulses, measuring a spectrum of the modulated train of optical pulses, recording the measured spectrum as an entry in a spectrogram at a position in the spectrogram corresponding to a relative delay between the modulation and the train of optical pulses, incrementing the relative delay, and repeating the above steps until the accumulated relative delay is equal to the period of the spectrogram. The train of optical pulses and the modulator are then characterized using the measured spectra recorded in the spectrogram.

Abstract: A method for identifying spectral impulses applies a window filter to an acquired waveform to produce a filtered waveform, and performs an FFT function on the filtered waveform to produce a spectrum of bins. An estimating window is located on the spectrum and centered on a target bin. Bins adjacent to the target bin are excluded and the remaining bins are used to form a noise estimate. The estimate is compared to the target bin and if the result exceeds a threshold value, a spectral impulse is identified.

Abstract: A channel plan with a corresponding test plan are implemented in connection with a plurality of nodes that communicate signals. The channel plan has one or more predefined specifications for each of one or more signal channels on each of the nodes. The channel plan may comprise a specification of the following, for example, for each of the channels: a label describing use of the corresponding channel, a center frequency, a bandwidth, a power level, information regarding the carrier roll-off, a default status indicator identifying whether the corresponding channel is currently allocated or reserved for future use, one or more default threshold levels for various tests, and an alternate center frequency that may be utilized by the corresponding channel. The channel plan enables a monitoring system to, among other things, conduct automatic periodic test plans, comprising tests, on the nodes, based upon the predefined data specified in the channel plan.

Abstract: Disclosed is a method and system for measurement of periodic gratings which have deviations which result in more than two materials occurring along at least one line in the periodic direction. A periodic grating is divided into a plurality of hypothetical layers, each hypothetical layer having a normal vector orthogonal to the direction of periodicity, each hypothetical layer having a single material within any line parallel to the normal vector, and at least one of the hypothetical layers having at least three materials along a line in the direction of periodicity. A harmonic expansion of the permittivity ? or inverse permittivity 1/? is performed along the direction of periodicity for each of the layers including the layer which includes the first, second and third materials. Fourier space electromagnetic equations are then set up in each of the layers using the harmonic expansion of the permittivity E or inverse permittivity 1/?, and Fourier components of electric and magnetic fields in each layer.

Abstract: The spectrum of a PCM signal is divided into bands. Combinations of a reference band inclusive of a highest frequency band and another band, one of the reference band and other band being normalized, are checked to identify a combination having a highest spectrum distribution correlation. The spectrum having the same distribution as the spectrum distribution of the reference band contained in the identified combination is scaled along an envelope function and added to a higher frequency side than the reference band to generate an output signal. A presence/absence of high frequency components of a PCM signal is detected. Only if there are high frequency components, the spectrum components are added to generate an output signal.

Abstract: A dynamic model of non-linear tuning behavior is used to tune a tunable device. The model quantifies a difference between a tuning characteristic of an ideal device and an actual tuning characteristic of the device. The model adjusts the tuning according to the difference. A method of compensated tuning of tunable device comprises employing a dynamic model of the tunable device to produce a compensated tuning control input to the tunable device during tuning. A tuning compensator for a tunable device comprises the dynamic model that is employed with an input tuning command to generate a compensated tuning command. A tuning-compensated YTF comprises a dynamic model-based tuning compensator and a YTF. A spectrum analyzer having a tuning-compensated preselector comprises a YTF preselector, a frequency converter, a video signal processor unit, a tuning compensator, and a controller. The tuning compensator uses the dynamic model to tune the preselector.

Abstract: A tuneable filter, for example an antenna filter in a single chip radio receiver, comprises a frequency selective circuit (12) including passive reactive components. At least some of the reactive components (48 to 52) are arranged as a bank (46 ) which includes switches (53 to 57) for switching at least one of the reactive components in the bank into the frequency selective circuit. A controller controls the switching means to select the or a combination of the reactive components which provides an optimum sensitivity for an input signal at a first frequency. The switch settings required to optimise the sensitivity for other frequencies is determined by measuring the decrease in sensitivity for other switch settings, with the input signal still at the first frequency, and using stored data about the shape of the frequency response of the tuneable filter.

Abstract: A method for determining the amplitude and phase angle of a measuring signal corresponding to a current or a voltage on an electrical power supply network by using sampled values of the measuring signal, a model of the measuring signal containing at least a sinusoidal component being used to calculate the amplitude and phase of the measuring signal with the sampled values by applying a recursive least-squares estimation method. In order to be able to determine the frequency of the measuring signal together with the amplitude and the phase angle, use is made of a model of the measuring signal in accordance with the relationship y=A·sin(2&pgr;ft+&phgr;), and by using this model and the sampled values (ym), the determination of the frequency of the measuring signal (um) as well is carried out via a recursive nonlinear least-squares estimation method. By expanding the signal model, measuring signals with a DC component and with frequencies that change over time also can be investigated.

Abstract: Headers of image frames are compressed. Header of a first frame is received, where the header includes a plurality of header parameters. Further, differences are determined between the header parameters and a plurality of default parameters, and non-default parameters are sent when there are differences. The header is then compressed to include only a first type of marker, and is sent through the transmission channel. In one embodiment, the non-default parameters are sent through a control channel, while the compressed header is sent through a data channel.

Abstract: The present invention relates to a method and system for efficiently determining grating profiles using dynamic learning in a library generation process. The present invention also relates to a method and system for searching and matching trial grating profiles to determine shape, profile, and spectrum data information associated with an actual grating profile.

Abstract: A method for measuring a bandwidth of a signal path between a data source and a data recipient involves sending a block of test data from the data source along the signal path to the data recipient, using that test data to obtain a measured bandwidth of the signal path, and transferring information from the data source along the signal path to the data recipient in accordance with the measured bandwidth. The measured bandwidth value can be calculated each time the data recipient accesses a website or the measured bandwidth value can be retained for future use.

Abstract: A system and method for analyzing order components present in a physical signal X acquired from a physical system. Measurement information for the physical signal X may be received, where the measurement information includes information indicating a plurality of order components of the physical signal X. Time frequency plot information visually indicating order components of the physical signal X may be displayed. User input selecting one or more of the visually indicated order components may be received. A time domain signal may be created based on the one or more selected order components and may then be presented to a user on a presentation device. Presenting the time domain signal on the presentation device may enable the user to analyze the physical signal X or the physical system. Where the physical system includes one or more rotating elements, the method may enable order components of the signal to be analyzed even when no rotation speed information (e.g.

Abstract: According to the invention a reference measurement is carried out without or with only one measurement object and the frequencies of the noise fraction are determined for the resulting frequency spectrum. Discrete measurement values are determined at equidistant sampling points in the form of complex-value overlays of oscillation functions and the noise and useful frequencies and by means of mathematical calculation methods corrected by the noise fractions. The measurement values corrected in this way are then subjected to a known method of frequency analysis.

Abstract: A field distribution measuring method for measuring a spatial distribution of an electric field or a magnetic field at a plurality of sampling points. The method includes the steps of continuously sweeping the sampling points by a probe, in which, based on spurious spectra generated by offsets between positions of the probe and measuring timings, a shift amount of the sampling points is computed, and, taking into account the shift amount, a distribution of electric fields or magnetic fields is measured. The method further includes a step of removing the measured noises generated due to the offsets between sweeping positions of the probe and the measuring timings.

Abstract: The present invention is intended to achieve measurement of electrode impedance that is not easily affected by fluid noise, and to accurately detect adhesion and discriminate the type of fluid.

Abstract: Described are techniques for processing data sets produced by analyzing a sample. The input data set is represented as rows of intensities over time for a particular mass to charge (m/z) range. A correlation matrix is produced in which each row of the input data set is correlated with every other row in the input data set. The correlation matrix is clustered or grouped such that those highly correlated m/z ranges are included in the same group. A set of one or more scans is selected for each group representing periods of interest within each group. Using the m/z values included in each cluster, a resultant sample spectra is created for each of the selected scans. The processing techniques may be used to identify parent and related fragment ions in the input data set and as a preprocessor producing resultant sampled spectra used as input to subsequent processing.

Abstract: A method for extracting components from signals in an electronic sensor (50) having a sensing element (52). The sensing element (52) generates a first signal (60) and a second signal (62). The method comprises the steps of: receiving the first signal (60) from the sensing element (52), the first signal (60) having a frequency at an event; sampling the second signal (62) from the sensing element (52) based on the frequency of the event, the second signal (62) having a plurality of components, one of the plurality of components being a first component of interest (112, 114); generating a synchronized second signal (100) in a time domain, the second signal (62) having the plurality of components; generating complex data (110) in a frequency domain from the synchronized second signal (100) in the time domain; and determining the first component of interest (112, 114) from the complex data (110). There is also a system in an electronic sensor (50) according to the above-described methods.

Abstract: A method for identifying a signal source in a predetermined space, the method including inventorying a set of identified signatures corresponding to a plurality of signal sources and recording a signal simultaneously at different locations of the predetermined space. Parameters related to the conditions under which the recordings are made are then stored, and a spectrum of the signal is determined. The method also includes detecting a line emerging from background noise of the spectrum by using a predetermined emergence threshold. The line is then compared with some or all of the signatures included in the set of identified signatures, and at least one signature corresponding to the line is selected to create at least one signature/line pair. Finally, a source of the signal is identified based on the selecting step.

Abstract: A first signal and a second signal are provided as two continuous signals having an identical fundamental frequency. A first spectrum which is either one of a frequency spectrum or a frequency power spectrum of the first signal in a predetermined time period is obtained. A second spectrum which is either one of a frequency spectrum or a frequency power spectrum of the second signal in the predetermined time period is obtained. A normalized value which corresponds a ratio of a difference between the first spectrum and the second spectrum and a sum of the first spectrum and the second spectrum at the fundamental frequency is obtained. A ratio of an amplitude of a signal component of the first signal and an amplitude of a signal component of the second signal is obtained based on the normalized value.

Abstract: System and method for estimating signal parameters (e.g., frequency, amplitude and/or phase) of one or more tones present in an input signal. Samples of the input signal are received, and a frequency transform of the samples generated. An amplitude peak in the frequency transform corresponding to the tone is identified. Two or more frequency bins are selected proximate to the identified frequency in the transform. A tone frequency value is determined that minimizes a difference between two or more expressions, each including respective numerator and denominator terms corresponding to respective frequency bins and whose ratios each represent a complex amplitude of the tone at a respective bin. Each expressions includes a tone frequency variable that represents a correct tone frequency value of the tone.

Abstract: Electric arc monitoring is effected by exploiting the discovery that electric arcs are fractal phenomena in that all essential information that signifies “arc” is contained in each fractal subset. These fractal subsets are logarithmically distributed over the arc spectrum. Monitoring of arcs is most advantageously effected on a fractal subset (16) of low logarithmic order where the amplitude is higher pursuant to the 1/f characteristic of electric arcs, where cross-induction among neighboring circuit is lower, and where travel between the arc (12) and the arc signature pickup (23) is longer than at the high frequencies customary for electric arc detection. Fractal subset transformation (17) reduces the danger of false alarms. Arc signature portions may be processed in out of phase paths (242, 342) or treated as modulated carriers (42) for monitoring.

Abstract: A method and apparatus for the characterization of optical pulses and modulators includes modulating, using a modulator, a train of optical pulses, measuring a spectrum of the modulated train of optical pulses, recording the measured spectrum as an entry in a spectrogram at a position in the spectrogram corresponding to a relative delay between the modulation and the train of optical pulses, incrementing the relative delay, and repeating the above steps until the accumulated relative delay is equal to the period of the spectrogram. The train of optical pulses and the modulator are then characterized using the measured spectra recorded in the spectrogram.

Abstract: A spectrum analyzer that may be implemented by a simple microcontroller that does not have a hardware multiply function is disclosed. The spectrum analyzer of the present invention utilizes at least five frequency bins. The input signal is sampled at four times the bin frequency. The input signal is sampled at twice the Nyquist rate, which results in symmetries in the sin(wn) and cos(wn) functions. These symmetries allow the in-phase and quadrature components of the input signal to be calculated by add, ignore or subtract operations instead of the more complex multiplication and integration operations. Accordingly, the energy for each bin may be calculated with a minimum number of multiply operations. Because the number of multiply operations have been significantly reduced, these multiply operations may be performed by software instead of hardware. As a result, the spectrum analyzer may be implemented with a simple processor that does not have a hardware multiply.

Abstract: A system and method is provided for detecting emitter signals and for determining a scan strategy for a receiver system that receives such emitter signals. When revisit times are computed for each receiver detecting method for an emitter, these revisit times may not be monotonically increasing or decreasing as expected due to discontinuities in the antenna model. A system and method are provided for detection and correction of such discontinuities.

Abstract: An improved method is provided for solving sequence matching and comparison problems using attractor-based processes to extract identity tokens that indicate sequence and subsequence symbol content and order. These attractor processes map the sequence from its original sequence representation space (OSRS) into a hierarchical multidimensional attractor space (HMAS). The HMAS can be configured to represent equivalent symbol distributions within two symbol sequences or perform exact symbol sequence matching. The mapping process results in each sequence being drawn to an attractor in the HMAS. Each attractor within the HMAS forms a unique token for a group of sequences with no overlap between the sequence groups represented by different attractors. The size of the sequence groups represented by a given attractor can be reduced from approximately half of all possible sequences to a much smaller subset of possible sequences.

Abstract: A system for measuring plasma electon densities (e.g., in the range of 1010 to 1012 cm−3) and for controlling a plasma generator (240). Measurement of the plasma density is essential if plasma-assisted processes, such depositions or etches, are to be adequately controlled using a feedback control. Both the plasma measurement method and system generate a control voltage that in turn controls the plasma generator (240) to maintain the plasma electron density at a pre-selected value. The system utilizes a frequency stabilization system to lock the frequency of a local oscillator (100) to the resonant frequency of an open microwave resonator (245) when the resonant frequency changes due to the introduction of a plasma within the open resonator. The amplified output voltage of a second microwave discriminator may be used to control a plasma generator (240).

Abstract: A method for determining the frequency of current ripples contained in the armature current signal of a commutated direct current (DC) motor includes determining frequency spectral results of the current signal and of a motor electric operating parameter. The frequency spectral results are subtracted from one another to determine the frequency spectral result of the current ripples contained in the current signal. The current ripple frequency is determined from the frequency spectral result of the current ripples contained in the current signal. The operating parameter may be the armature voltage signal, or the armature current signal at a different motor operating state than the motor operating state of the current signal used in the step of determining the current signal frequency spectral result. The rotational speed of a motor shaft is determined based on the current ripple frequency. The shaft rotational position is determined based on the rotational shaft speed.

Abstract: Spectrum estimates of unevenly spaced timestamped data collected over a network. Unevenly spaced data is not suitable for processing by traditional methods such as Fast Fourier Transforms. Spectrum estimates of timestamped data collected over a network are calculated using a Continuous Fourier Transform. If the time between samples is long, spectrum estimates may be computed incrementally.

Abstract: A method for extracting components from signals in an electronic sensor (50) having a sensing element (52). The sensing element (52) generates a first signal (60) and a second signal (62). The method comprises the steps of: receiving the first signal (60) from the sensing element (52), the first signal (60) having a frequency at an event; sampling the second signal (62) from the sensing element (52) based on the frequency of the event, the second signal (62) having a plurality of components, one of the plurality of components being a first component of interest (112, 114); generating a synchronized second signal (100) in a time domain, the second signal (62) having the plurality of components; generating complex data (110) in a frequency domain from the synchronized second signal (100) in the time domain; and determining the first component of interest (112, 114) from the complex data (110). There is also a system in an electronic sensor (50) according to the above-described methods.

Abstract: A highly time resolved impedance spectroscopy that enhances the measurement of the dynamics of non-stationary systems with enhanced time resolution. The highly time resolved impedance spectroscopy includes an optimized, frequency rich a.c., or transient, voltage signal is used as the perturbation signal, non-stationary time to frequency transformation algorithms are used when processing the measured time signals of the voltage and current to determine impedance spectra which are localized in time; and the system-characterizing quantities are determined from the impedance spectra using equivalent circuit fitting in a time-resolution-optimized form. Methods and apparatus for processing impedance spectra data are also provided.

Abstract: A system and method for estimating parameters of multiple tones in an input signal. The method includes receiving samples of the input signal, generating a frequency transform (FT) of the samples, identifying multiple amplitude peaks in the FT corresponding to the tones, and determining parameter estimates characterizing each of the multiple tones based on the peaks. For each tone, the effects of the other tones are removed from the FT of the peak of the tone using the parameter estimates of the other tones to generate modified FT data for the tone. Single tone estimation is applied to the modified FT data to generating refined parameter estimates of the tone, which is used to update the parameter estimates of the tone. After refining the estimates for each tone, the entire process may be repeated one or more times using successive refined estimates to generate final estimates for the parameters.

Abstract: A manufacturing apparatus which includes a rotary machine, includes: a plurality of accelerometers configured to measure diagnosis time series data attached to the rotary machine at locations where variations of the rotary machine are different; a frequency analysis device configured to perform a frequency analysis on the diagnosis time series data measured by the plurality of accelerometers; a time series data recording module configured to generate diagnosis data based on variations in characteristics of vibration corresponding to an analysis target frequency and to record the diagnosis data; and a life prediction unit configured to analyze the diagnosis data to determine a life span of the rotary machine.

Abstract: A method that analyzes mass spectra using a digital computer is disclosed. The method includes entering into a digital computer a data set obtained from mass spectra from a plurality of samples. Each sample is, or is to be assigned to a class within a class set having two or more classes and each class is characterized by a different biological status. A classification model is then formed. The classification model discriminates between the classes in the class set.

Abstract: A method comprises: sampling a current waveform of an induction machine to obtain sampled points; characterizing the sampled current over a selected first time window to obtain characterized points; subtracting the characterized points from respective sampled points to obtain a residual signal comprising residual points; obtaining a frequency spectrum representative of the residual signal over a selected second time window; and identifying a rotor bar pass frequency from the frequency spectrum. The method is typically carried out by a system comprising a computer, a computer-readable medium, or combinations thereof.

Abstract: A device, method and computer program product are disclosed for indicating a function deviation of one or more details of manufacturing equipment using frequency component analysis for analyzing deviations between a nominal product shape and an actual product shape of a product using surface data of a physical surface, the product having been processed by the manufacturing equipment. The analysis can be based on the surface data and a set of function deviation indicating frequencies corresponding to frequencies at which function deviations occur in the one or more details. The function deviation indicating frequencies can be comprised in a frequency map. A method of configuring a frequency map is also disclosed.

Abstract: An observation apparatus according to one embodiment can include a timing generating unit (2) that generates a timing signal at a predetermined period. A sampling unit (3) can sample a current observation signal of a power supply current on the basis of the timing signal, and store sampled data in data storing unit (5). A data number adjusting unit (6) can adjust the number of data samples to a number that is a power of two. An arithmetic operating unit (4) can Fourier-transform the adjusted data to generate frequency spectrum results of the current observation signal. In addition, a failure inspection apparatus according to one embodiment analyzes the frequency spectrum of an integrated circuit under observation to determine a failure condition of the integrated circuit.

Abstract: Detecting failed integrated circuit among integrated circuits, by (a) assuming that all integrated circuits under test define under-test set, and testing each one of the integrated circuits in the under-test set, (b) removing integrated circuits judged to be in failure in step (a) from the under-test set, (c) measuring spectrum of a current supplied from a power source into each one of integrated circuits in under-test set, (d) calculating both mean value and standard deviation of spectrum for under-test set, (e) judging whether an integrated circuit is in failure or not, based on both the mean value and the standard deviation of the spectrum, (f) removing integrated circuits having been judged to be in failure in step (e), from the under-test set, and (g) judging under-test set to be in no failure. Thus, it possible to find failed integrated circuits without preparing data of integrated circuit in no failure, as a reference.

Abstract: A DSP#B 6 executes, prior to data conversion, interpolation (see FIG. 2) in order to interpolate discrete spectra obtained via the FFT processing by a DSP#A 5. In the interpolation, the DSP#B 6 executes two-point interpolation if the difference between two discrete spectrum data pieces F(j) and F(j+1) is greater than a predetermined threshold &egr; and four-point interpolation if the difference is smaller than &egr;.

Abstract: A method of determining distance to fault of a transient event in a transmission system uses per frequency triggered I and Q data representing voltage and phase of a return signal in the frequency domain. Initially a result set of data entries, one for each discrete frequency in a specified frequency range, is filled with zeros and an initial acquisition set of per frequency I and Q data from the transmission system is used to fill a reference set of data entries. Subsequent acquisitions of per frequency data sets are used to fill a current set of data entries. Between each acquisition of data sets for the current set a comparison is made, entry by entry, between the current set and the reference set, and the data from the current set is used to update the corresponding entry in the result set when the difference exceeds a specified tolerance.

Abstract: A signal analyzer has a display with two regions. In a first region there is displayed a first waveform representing a signal. The first waveform is shown in two dimensions. One dimension represents signal amplitude and one dimension represents signal frequency. In a second region is displayed a second waveform. The second waveform represents a subset of data points of the first waveform. The second waveform also is shown in two dimensions. One dimension represents signal amplitude and one dimension represents signal frequency.

Abstract: A technique for determining the amplitudes of frequency components of a waveform sampled from an automatic test system includes assembling a list of N frequencies expected to be found in the sampled waveform. A test program running on the tester generally supplies the list of frequencies. The technique assumes that the sampled waveform conforms to an idealized waveform model that mathematically corresponds to a sum of N sinusoids. Each of the N sinusoids that make up the model has unknown amplitude and a frequency that equals one of the N frequencies in the list of frequencies. The technique attempts to solve for the unknown amplitude of each of the N frequencies by mathematically minimizing, via a linear least-squares algorithm, the difference between the model and the actual, sampled waveform.

Abstract: A method of measuring impedance is based on carrier function Laplace transform. The measurement includes detecting a response signal from a device under test, to which signal an excitation such as a pulse, interrupt or constant load is applied. Resulting data is fitted to a carrier function, selected so as to be capable of providing a good fit and for which an analytical Laplace transform is known, in order to obtain parameters of such function providing best fit. Obtained parameters are further substituted into the analytical expression of Laplace transform of carrier function which is used to calculate a frequency dependent impedance function in the Laplace domain. The resulting impedance function is used for calculating the impedance spectrum in a frequency domain and for calculating the measurement error of the frequency domain impedance spectrum using the standard deviations of the parameters, obtained during fitting of time-domain data.

Abstract: There is provided a method of detecting an integrated circuit in failure among integrated circuits, based on spectrum which is a result of analyzing a frequency of a current running through an integrated circuit when a test signal is applied to the integrated circuit, comprising the steps of (a) assuming that all integrated circuits under test define a under-test integrated circuit set, and testing each one of the integrated circuits in the under-test integrated circuit set in a conventional manner, (b) removing integrated circuits having been judged to be in failure in the step (a), from the under-test integrated circuit set, (c) measuring spectrum of a current supplied from a power source into each one of the integrated circuits in the under-test integrated circuit set, (d) calculating both a mean value and standard deviation of the spectrum for the under-test integrated circuit set, (e) judging whether an integrated circuit is in failure or in no failure, based on both the mean value and the standard devia