704 results about "Frequency spectrum analysis" patented technology

The present invention is embodied in a system and method for performing spectral analysis of a digital signal having a discrete duration by spectrally decomposing the digital signal at predefined frequencies uniformly distributed over a sampling frequency interval into complex frequency coefficients so that magnitude and phase information at each frequency is immediately available to produce a modulated complex lapped transform (MCLT). The present invention includes a MCLT processor, an acoustic echo cancellation device and a noise reducer integrated with an encoder / decoder device.

A system, method and software for determining a position of a source of a radio emission. Receive signal strength data associated with reception of radio emissions is generated at each of a plurality of radio sensor devices that are at corresponding known positions in an area where the radio emissions are occurring. Using characteristics associated with reception of the radio emissions at each of the sensor devices, the receive signal strength data generated by each of the sensors is matched as corresponding to a radio emission from the same source. The characteristics used to match receive signal strength data may include spectrum analysis data and / or timing analysis data. Once the receive signal strength data is matched, position computations may be performed on the appropriate set of receive signal strength data to compute the position of the source of the radio emission.

A method useful for evaluating abnormal body tremors wherein a subject is positioned onto a support surface and one or more components of the load exerted by the subject upon the support surface are measured. Simultaneously, the cardiac activity of the subject is also recorded and the time interval between each consecutive heartbeat is computed. The measured load output is modified to normalize the weight of the subject and then plotted against a modified frequency wherein each time interval between heartbeats represent a unit of time and a selected equal number of force measurement samples are interpolated between each heartbeat. The frequency spectrum analysis of such a modified power spectrum graph yields information about body tremor which can be compared to a prior analysis of the same subject or to the same analysis of a standard. The standard is created using the identical method upon, preferably, a sufficient number of subjects known to be free of abnormal body tremor to yield an average measure useful for comparison and diagnostic purposes.

A system and method for identifying minor echoes present in an input signal in the situation where a set of major echoes has already been identified from the input signal. The method includes: computing a spectrum F corresponding to a sum of the major echoes; computing a weighted power spectrum SM of the spectrum F; subtracting the weighted power spectrum SM from a weighted power spectrum PIN of the input signal to obtain a difference spectrum; performing a stabilized division of the difference spectrum by a conjugate of the spectrum F to obtain an intermediate spectrum; computing an inverse transform of the intermediate spectrum to obtain a time-domain signal; and estimating parameters one or more of the minor echoes from the time-domain signal. The echo parameters are usable to remove at least of portion of the one or more estimated minor echoes from the input signal.

An intrusion detection system comprises a plurality of sensors (2A . . . 2X) and a corresponding plurality of receivers (3A. . . 3X). Each receiver receives, via the associated sensor, radio frequency signals comprising a multiplicity of transmissions at different frequencies within a predetermined frequency spectrum. The receiver detects the radio frequency signals and computes, for each of a plurality of successive time intervals and for each of the transmission frequencies, a measurement of signal amplitude over the time interval; compares such signal amplitude measurement with at least one threshold and, if the amplitude exceeds the threshold for a predetermined time period, generates a potential alarm signal. A processor (4) compares potential alarm signals from a plurality of sensors and determines that an intrusion has occurred if the potential alarm signal for a particular station does not coincide with a potential alarm signal for a neighboring sensor. Each receiver may output an intruder alarm signal when potential alarm signals occur simultaneously for more than a preset number of a multiplicity of the transmission frequencies.

A voice activity detector that detects talkspurts in a given signal at a high accuracy, so as to improve the quality of voice communication. A frequency spectrum calculator calculates frequency spectrum of a given input signal. A flatness evaluator evaluates the flatness of this power spectrum by, for example, calculating the average of power spectral components and then adding up the differences between those components and the average. The resultant sum of differences, in this case, is used as a flatness factor of the spectrum. A voice / noise discriminator determines whether the input signal contains a talkspurt or not, by comparing the flatness factor of the frequency spectrum with a predetermined threshold.

A system for monitoring reverse paths of a bi-directional cable communication network such as a CATV network, to detect and analyze ingress signals entering a reverse path and ending at a network sub-headend or headend through a corresponding one of communication lines, comprises a plurality of radio frequency signal detectors connected thereto. The radio frequency signal detectors are provided with bandpass filter for receiving a radio frequency signal within the frequency band used, to generate corresponding output signals indicative of the strength of the received radio frequency signal. The output signal generated by the frequency signal detector which is coupled to the communication line corresponding to the ingress signal carrying path is indicative of the strength of the received ingress signal with received reverse signals. The system further comprises a signal processor for analyzing the detector output signals through comparison with one or more predetermined ingress thresholds to generate an alarm signal whenever the ingress signal is detected. The system further comprises a control computer receiving the alarm signal to generate monitoring sequence control data indicative of the communication line corresponding to the ingress signal carrying path to be monitored. The system also comprises a selector switch having a plurality of inputs being connected to the communication lines and being responsive to the monitoring sequence control data to select the input connected to the communication line to be monitored, and signal monitoring instrumentation such as a spectrum analyzer and a broadband analyzer coupled to an output of the switching device and being responsive to the monitoring sequence control data for analyzing the ingress signal and generating alarm message data accordingly. The control computer receives the alarm message data to further generate diagnostic sequence control data for the monitoring instrumentation also used to determine source characteristics of the ingress signal.

A PIM measurement circuit enables making forward and reverse PIM measurements on any 1 port (reflection) or 2 port (transmission) device with the ability to determine in distance where individual PIM impairments are located as well as their magnitude. The PIM measurement circuit includes two frequency sources that are provided through a combiner for a CW characterization of the PIM circuit. To enable distance determination, an FM measurement is created by using a saw tooth offset sweep generator attached to one of the two frequency sources. With downconversion and processing of signals from the PIM impairments, the FM signal provides a frequency variation that is converted using a Fourier transform or spectrum analysis for separation of frequencies, enabling determination of the distance of the PIM sources as well as their magnitudes.

The invention discloses a flicker detection method and a device thereof and the device can carry out real-time detection without affecting the image quality. The method comprises the following steps of: reading a current frame, and obtaining the vertical waveform of the current frame; carrying out frequency spectrum analysis on the vertical waveform or carrying out frequency spectrum analysis on the difference (frame difference waveform) of the vertical waveform of the current frame and the vertical waveform of the historical frame; if the peak exists on the frequency spectrum, judging whetherthe flicker exists or not according to the approaching degree of the frequency of the peak corresponding point and the theoretical peak frequency point.

The invention discloses a measuring method and device for measuring the particle granularity, consistency and density, which relates to the technical field of ultrasonic measurement. The invention aims at solving the technical problem of increasing the commonality and the precision of the ultrasonic measurement. The measuring device includes a computer, a signal process circuit, a pulse wave launch / receive circuit and a broadband transducer, which are orderly connected together; the broadband transducer is arranged at the external side of a baffle plate. The process procedures of the computer are as follows: ultrasonic amplitude phase spectrum is obtained after the rapid Fourier transformation of the signal, and then the phase spectrum is converted to obtain a reflection coefficient, the acoustic characteristic impedance, the acoustic attenuation coefficient and the sound velocity; the compound density can be calculated by the measuring value, and the consistency can be calculated through the known particle and the density of the continuous medium; the frequency analysis of the direct reflection wave and the transmission echo is carried out to obtain difference between the acoustic attenuation spectrum and the theoretical acoustic attenuation spectrum, and the difference is then regarded as the objective function, and then is optimized with optimization method to calculate the distribution of the particle granularity. The invention has the advantages of measuring and analysis basing on the reflecting ultrasonic, great commonality and precise measuring result.

The invention provides an unmanned aerial vehicle signal processing device and a processing method thereof. The device comprises a receiving module (1), a monitoring module (2), an early warning module (3), an interference module (4) and a transmitting module (5). The early warning module (3) comprises a storage unit (10) which stores unmanned aerial vehicle frequency domain data and a comparison unit (11) which compares current frequency domain data transmitted by a frequency spectrum analysis unit (9) with the unmanned aerial vehicle frequency domain data stored in the storage unit (10). The early warning module (3) alarms when the comparison result is in the preset range. The interference module (4) comprises a baseband signal generator (12) which sets baseband signal frequency, an interference modulator (13) which modulates a baseband signal into a noise signal, a working amplifier (14) which increases noise power and a combiner (15) which combines different noise frequency bands. Close-up flight of an unmanned aerial vehicle can be warned in advance by detecting working frequency range of the unmanned aerial vehicle, and close-up flight of the unmanned aerial vehicle to the protected security area can be prevented.

A video frame is input to a spectrum analyzer, which transforms the frame from a spatial domain into a frequency domain. A resolution determiner analyzes the output of the spectrum analyzer, thereby selecting a resolution appropriate for the video frame. Then, a resolution converter converts a resolution of the video frame into the resolution selected by the resolution determiner. Thereafter, the video frame is subjected to a coding process by block divider, DCT transformer, quantizer and variable-length coder so as to be output as a coded bit stream. By coding the input video frame at a resolution corresponding to the high-frequency component in the frame, a video of higher quality can be obtained with the bit rate reduced.

A hearing device is adapted to be arranged on or at least partly implanted in an individual's head and comprises: an input unit providing an input audio signal; a signal processing circuit adapted to process the input audio signal; an output unit adapted to provide an audible signal to the individual; one or more electrodes adapted to detect electric brain potentials of the individual; and a brainwave measurement circuit adapted to determine one or more EEG signals from electric signals received from the one or more electrodes. The hearing device further comprises: a first spectrum analyser determining first audio spectra; a reconstructor adapted to repeatedly reconstruct second audio spectra; a first correlator to determine coherence between the first and the second audio spectra; and a control unit adapted to alter said processing in dependence on the coherence.

A seismic coherence algorithm based on wavelet transformation comprises the following steps: 1) preprocessing the seismic data; 2) executing fine frequency spectrum analysis to the processed seismic data for confirming the effective frequency spectrum range of seismic data; 3) executing horizon interpretation to the seismic data and executing processions of interpolation, smoothing, etc.; 4) using seismic data and the interpreted seismic horizon as input, executing wavelet transformation to a certain seismic channel for inputting earthquake data with a high resolution derivative wavelet function for obtaining the wavelet transformation frequency division result; 5) computing the instantaneous amplitude or / and instantaneous frequency or / and instantaneous phase of instantaneous wavelet field; 6) computing the instantaneous coherence using a coherence algorithm based on wavelet instantaneous phase or a coherence algorithm based on wavelet transformation; 7) reconstructing the instantaneous coherence for obtaining high-frequency or low-frequency coherent data volume; 8) repeating the steps 4-7 to each seismic channel for obtaining the coherence computing result of all seismic channels; and 9) drafting with the computed instantaneous coherent data.

Logic analyzers and real-time spectrum analyzers use real-time statistical processes as a basis for creating a trigger. The statistical displays within a test and measurement system such as a Logic Analyzer (LA) or Spectrum Analyzer (SA) or other instrument are used in a user interface to define a trigger based on the statistical event itself. In brief, the invention is a Real Time Statistical trigger established by the user through a direct interaction with the Real Time Statistics displays. This interaction can be via a graphical user interface, or the user interface can employ a non-visible display (e.g., a speaker) or input device (e.g., a microphone).

This invention relates to one complete phase time displacement different frequency spectrum correction method, which measures the signal frequency rate, phase bit, range value parameters with high accuracy to make phase meter, frequency meter and spectrum analyzer, laser distant devices. The invention adopts technique key by use of whole phase FFT frequency spectrum analyze method for two existent lag relationship frequency spectrum to correct the analyze results by time displacement difference method and two time phase spectrum analyze results.

The invention discloses a method for designing a cognitive high-speed wireless communication system under a discrete spectrum condition, and particularly discloses a cognitive high-speed wireless communication system and method under a discrete spectrum condition. The system comprises an authorized frequency band analysis module, an unauthorized frequency band analysis module and a data modulating module, wherein the authorized frequency band analysis module is used for performing frequency spectrum analysis on authorized frequency bands of a communication system to obtain a first available frequency band; the unauthorized frequency band analysis module is used for analyzing other frequency bands of the communication system except the authorized frequency bands or the authorized frequency bands of at least one other system different from the communication system to obtain a second available frequency band; and the data modulating module is used for modulating data to be transmitted in an OFDM / OFDMA (Orthogonal Frequency Division Multiplexing / Orthogonal Frequency Division Multiple Access) mode based on the first available frequency band and the second available frequency band.

The invention concretely discloses a wide area measurement system which is applied to a phasor measurement unit and based on local frequency spectrum analysis, which comprises a WAMS main station, a PMU substation and a power data network; the PMU substation comprises a GPS time service unit, a synchronized phasor acquisition unit, and a data centralized processing unit; the WAMS main station sends measurement and configuration information, measurement information to be detected and thresholds of a plurality of low-frequency oscillation parameters and receives the parameters measured by low-frequency oscillation which exceed the thresholds and return from each PMU substation for comprehensive analysis in order to obtain overall oscillation mode information; the PMU substation also comprises a frequency spectrum analysis unit and a low-frequency oscillation detection unit. The invention also discloses a phasor measurement unit based on the local frequency spectrum analysis. The adoption of the system and device of the invention can realize real-time and rapid low-frequency oscillation detection and analysis of a large-scale electricity grid.

A time-interleaved analog-to-digital converter stores in a correction information memory, correction information required to correct an error between signals output by a plurality of N analog-to-digital converters in advance. At this time, in order to enable acquisition of data required for a correction processing within a short period of time, a signal generator causes the plurality of N analog-to-digital converter to input a calibration signal including a plurality of signal components, each of which is positioned at a desired frequency in a bandwidth in which N / 2 times of a sampling frequency Fs is defined as an upper limit, the signal components appearing in a bandwidth in which half times of the sampling clock frequency Fs is defined as an upper limit by sampling the analog-to-digital converters. A correction information calculating unit carries out a spectrum analysis relevant to analog-to-digital converted signals output by the plurality of N analog-to-digital converters in response to the calibration signal, thereby obtaining an amplitude and a phase of a plurality of signal components, newly obtaining the correction information, based on the amplitude and phase, and updating contents of the correction information memory in accordance with newly obtained correction information.

The invention relates to the precision shaft angle measuring instrument precision detection filed, more particularly to an angle measurement precision detection apparatus of an encoder and a detection method thereof. The apparatus comprises a coupling assembly, a precision main shaft, a motor, a precision encoder, a connection base, a rotary table, a workbench, and a computer system. The precision encoder is employed as a reference and is connected with the precision main shaft coaxially. The precision main shaft is driven by the motor; and an output shaft of the precision main shaft is connected with a detected encoder. The computer controls the rotating speed and the position of the motor as well as simultaneously collects angle measurement data of the precision encoder and the detected encoder; and an error value representing deviation of the position output of the detected encoder from the position output of a reference precision encoder is obtained in rotation angles from 0 degree to 360 degrees of the precision main shaft. And processing is carried out by the computer to provide various measurement errors of the detected encoder and error frequency spectrums. According to the invention, beneficial effects are as follows: there are lots of measurement points and measurement can be carried out continuously, so that various errors of a detected encoder can be reflected; a frequency spectrum analysis on an error source can be carried out; automatic measurement is carried out, the measuring period is short and efficiency is high; and electronization of data processing is realized as well as detection data are filed.

Methods for recovering a detected signal in non-contact vital sign detection are provided. According to one embodiment, a detected reflected signal from a non-contact vital sign detection system can be received and provided along I channel and Q channel signal lines. A complex signal S(t) can then be reconstructed from the I channel and Q channel signal lines through complex signal demodulation. A Fourier transform can be used to obtain the detected signal's spectrum for spectrum analysis. Angular demodulation can be used to recover the information corresponding to original body movement. The complex signal demodulation and angular demodulation techniques used to provide information to determine original body movement are capable of avoiding the null detection point without limitations on frequency tuning or channel selection.

The invention relates to a method for diagnosing faults of a planetary gear system of a wind driven generator under variable rotating speed. The method for diagnosing the faults of the planetary gear system of the wind driven generator under the variable rotating speed aims to overcome defects in a method for diagnosing variable rotating speed faults in the prior art. According to the method for diagnosing the faults of the planetary gear system of the wind driven generator under the variable rotating speed, a method that order data envelopment analysis is carried out on signals is adopted, namely, input (output) shaft rotating speed signals n(t) are obtained through a rotating speed sensor, then a fitting function (please see the formula in the specification) is obtained through fitting, a function (please see the formula in the specification) of changes of rotating angles along with time is obtained through integration, a time sequence tk of equal angle resampling is obtained through an interpolation method, interpolation is carried out on accelerated speed vibration signals Y(t) through the time sequence tk to obtain equal angle resampling signals (please see the symbol in the specification), then FTP is carried out on the envelop of the equal angle resampling signals (please see the symbol in the specification), and thus an order envelop spectrum can be obtained. The problem brought by the variable rotating speed can be well solved through the order analysis, interference of noise can be well restrained through envelop analysis, and thus the order envelop method can be well applied to fault diagnosis of the planetary gear system of the wind driven generator.

This invention relates to test to the passive intermodulation performance of the communication system, which controls an emitter to emit test signals according to a preset mode, controls a receiver to scan and receive the signals in the test bands and analyze spectrums of the received signals to evaluate the entire passive intermodulation performance of the base station, in which, the original outside interference signals are received at the shut-off state of the emitter to eliminate its influence and measure the performance accurately and the received test bands are computed accurately by the known carrier frequency sphere, intermodulation stages and the received frequency sphere parameters and the test signal receiving quality is increased by scanning the emitted and received continuous waves.

A time-interleaved analog-to-digital converter stores in a correction information memory, correction information required to correct an error between signals output by a plurality of N analog-to-digital converters in advance. At this time, in order to enable acquisition of data required for a correction processing within a short period of time, a signal generator causes the plurality of N analog-to-digital converter to input a calibration signal including a plurality of signal components, each of which is positioned at a desired frequency in a bandwidth in which N / 2 times of a sampling frequency Fs is defined as an upper limit, the signal components appearing in a bandwidth in which half times of the sampling clock frequency Fs is defined as an upper limit by sampling the analog-to-digital converters. A correction information calculating unit carries out a spectrum analysis relevant to analog-to-digital converted signals output by the plurality of N analog-to-digital converters in response to the calibration signal, thereby obtaining an amplitude and a phase of a plurality of signal components, newly obtaining the correction information, based on the amplitude and phase, and updating contents of the correction information memory in accordance with newly obtained correction information.

A transmitter for transmitting signals to targets and a receiver for receiving signals reflected from targets are included. The transmitter outputs CW signals for detecting direction and velocity of the target. The receiver performs: a function of receiving signals reflected from targets with a plurality of receiving antennas at the same time as transmitting from the transmitter, and performing spectral analysis with respect to receiving signals to thereby classify them by velocity component; a function of correlating signals of the receiving antenna systems; a function of integrating the signals correlation-processed; and a function of obtaining phase fronts of signals made incident on an antenna face from the phase differences of signals between receiving antennas, and performing two-dimensional FFT to the outputs to thereby measure the direction and velocity of the target.

A method for analyzing a digital audio signal associated with a baby cry, comprising the steps of: (a) processing the digital audio signal using a spectral analysis to generate a spectral data; (b) processing the digital audio signal using a time-frequency analysis to generate a time-frequency characteristic; (c) categorizing the baby cry into one of a basic type and a special type based on the spectral data; (d) if the baby cry is of the basic type, determining a basic need based on the time-frequency characteristic and a predetermined lookup table; and (e) if the baby cry is of the special type, determining a special need by inputting the time-frequency characteristic into a pre-trained artificial neural network.

The invention relates to the technology of digital signal processing, and provides a self-adaptive high-precision fast spectral analysis method which solves the problem that an existing spectral analysis method is large in error and poor in precision. According to the technical scheme, the self-adaptive high-precision fast spectral analysis method comprises the steps of firstly collecting analog signals, carrying out preprocessing of smoothing, and then carrying out analog-digital conversion to obtain sampling data; selecting 28 data to carry out FFT processing to obtain preliminary signal frequency spectrum information, carrying out peak searching, and then carrying out spectral line aliasing recognition on the preliminary signal frequency spectrum information; if aliasing does not exist, carrying out frequency spectrum correction processing on the preliminary signal frequency spectrum information to obtain the frequency, the amplitude and the initial phase information of the signals; if the aliasing exists, carrying out repeated analysis band-pass filtering thinning processing on the preliminary signal frequency spectrum information, and then carrying out the frequency spectrum correction processing to obtain the frequency, the amplitude and the preliminary phase information of the signals respectively. The self-adaptive high-precision fast spectral analysis method has the advantages that under the premise that calculation precision is ensured, the calculation amount is reduced to a large extent, and the self-adaptive high-precision fast spectral analysis method is suitable for spectral analysis.

The invention provides a pre-stack seismic data frequency band expanding method of combining well information and horizon information. The pre-stack seismic data frequency band expanding method comprises steps that signal-to-noise ratio spectrum analysis, spectral analysis, and band division scanning of seismic data are carried out to determine a dominant frequency band and to-be-compensated frequency bands; correction and well-seismic matching of well logging data are carried out to construct a well-side expected seismic record; by using a well point reflection coefficient, a well-side seismic record, and a horizon interpretation data, a sparse reflection coefficient section is constructed, and then expected seismic records of non-well points are acquired; by adopting an original seismic record and a reversed wavelet convolution, the expected seismic record is approached, and a corresponding bilateral reversed wavelet is acquired; a frequency-expanding operator acquired by a stacked record is used for a CRP trace gather, and the frequency-expanding operator is used to process every data of the CRP trace gather to acquire the high frequency frequency-expanding record and the low frequency frequency-expanding record of the CRP trace gather; the data reconstruction of the low frequency data acquired by the frequency expansion, the original dominant frequency band, and the high frequency data acquired by the frequency expansion is carried out to acquire wide frequency band seismic data.