163 results about "Amplitude frequency response" patented technology

The invention discloses an optical device measuring method and device based on double sideband modulation, which belongs to the technical fields of optical device measuring and microwave photonics. An optical double sideband modulation method is used to modulate a radio frequency signal to a first optical carrier signal, so as to generate a double sideband modulation signal. The double sideband modulation signal passes through an optical device to be measured to carry out beam combining with a second optical carrier signal. Frequency difference is between the second optical carrier signal and the first optical carrier signal. A photoelectric detector is used to carry out beat frequency on the signals after beam combining. The amplitude information of a +1 order sideband signal and a -1 order sideband signal in the beat frequency signals is extracted. The frequency of the radio frequency signal is scanned, so as to acquire the broadband amplitude frequency response of the optical device to be measured. The invention further discloses an optical device measuring device based on double sideband modulation. According to the invention, the system complexity and the cost are reduced; the measuring range and the measuring efficiency are greatly improved; and more importantly, a new direction is opened up for an optical device measuring technology.

The utility model discloses a method for testing the frequency properties of the photoelectric detector used for fiber optic gyroscopes. A signal generator produces sinusoidal signals and adds the signal to a light intensity modulator to carry out sinusoidal modulation on the optical power of the optical signal from the fiber source in order to produce an optical signal with sinusoidal components. The measured photodetector converts the modulated optical signal into an electrical signal and samples the electric signal by means of high-speed data acquisition card, then conducts narrowband filter and signal processing over the collected samples and calculates the corresponding frequency response. The frequency sequence pre-selected by a numerical control system changes the frequency at which the sine wave generator (NC) system sends out signals , tests a series of frequency point responses, which can be combined into an amplitude frequency response curve of the measured photodetector, and the curve is transmitted to the terminal computer for displaying and storage. By controlling all the test processes by numerical control system, the utility model has the advantages of automatic measurement, fast testing speed, high testing precision, and therefore is suitable for carefully weighing the photodetector frequency performance in the whole operating frequency range.

The invention discloses an optical device frequency response measurement method and a system. The method is characterized in that an optical carrier wave signal of a single wavelength is input into a frequency shift module with a carrier wave so that an optical detection signal with a carrier wave component and a frequency shift component is acquired; after the signal passes through a device to be detected, a radio frequency signal is acquired through a beat frequency of an optical detection module; a radio frequency amplitude phase extraction module whose working frequency is the same with a frequency shift amount is used to extract an amplitude and a phase information of the radio frequency signal so that combination amplitude frequency response and phase frequency response of an optical device to be detected at two frequency component positions of the optical detection signal are obtained; through calculation, the amplitude frequency response and the phase frequency response at the two frequency component positions are acquired respectively; a wavelength of the optical carrier wave signal is changed and the above processes are repeated so that frequency response of the optical device to be detected is acquired. The invention also discloses an optical device frequency response measurement system. Compared to the prior art, by using the method and the system, the amplitude phase extraction module is only requested to measure a fixed single frequency point so that cost is greatly reduced and simultaneously a bandpass device can be measured.

The invention discloses a probabilistic neural network-based tolerance-circuit fault diagnosis method, which comprises the following steps of: selecting a pulse signal source as the energization of a fault circuit to be detected; carrying out Monte Carlo analysis on the fault circuit so as to obtain an amplitude-frequency response signal of the fault circuit to be detected; carrying out three-layer wavelet packet decomposition on the amplitude-frequency response signal of the fault circuit so as to obtain low and high frequency coefficients of the amplitude-frequency response signal, carryingout threshold quantification on the wavelet packet decomposition coefficients, then carrying out wavelet packet reconstruction according to the lowest-layer low frequency wavelet packet decompositioncoefficients and the high frequency wavelet packet decomposition coefficients subjected to threshold quantification so as to complete the de-noising processing of the wavelet packet; calculating the band-gap energy of the response signal according to the low and high coefficients obtained after wavelet packet reconstruction, and constituting a fault characteristic vector by using the band-gap energy; and inputting the fault characteristic vector in a fault grader of the probabilistic neural network to realize circuit fault diagnosis. The method has the advantages of high right fault diagnosisrate, simple structure, short training time, high fault tolerance and strong extrapolation ability.

The invention brings forward a harmonic wave measuring and correcting method for capacitor voltage transformers through transformation ratio fitting. The method includes the steps: establishing a consistent equivalent circuit for capacitor voltage transformers with the same voltage level, conducting fitting according to equivalent circuit component parameters of a preset model, obtaining a transformation ratio amplitude-frequency response curve and a phase frequency response characteristic curve, adjusting the curves through a translation method or the like on the basis of a fitting result for different equivalent circuit component parameters of other models, and finally realizing correction. The wideband characteristics of capacitor voltage transformers are taken as standards for the actual transformation ratio of the capacitor voltage transformers, a measurement result of the capacitor voltage transformers is corrected at the harmonic frequency, and the problem that capacitor voltage transformers cannot be applied to harmonic wave measurement is solved. The harmonic wave measuring and correcting method is simple in calculation, exhibits the real-time performance, and enables the application bandwidth of capacitor voltage transformers to be increased.

The invention discloses a variable mass dynamic vibration absorber control method. A sensor used for collecting main system input and output vibration signals is arranged on a compound system composed of a main system-variable mass dynamic vibration absorber, and when the minimum inherent frequency omega m and the maximum inherent frequency omega n of the variable mass dynamic vibration absorber are used respectively, an amplitude-frequency response curve of a main system in the frequency range (0,omega t] is formed; as for the variable mass dynamic vibration absorber control method, while the main system works, the main system vibration signals are collected through the vibration sensor, and excitation frequency omega exerted by the external world is calculated through fast Fourier transform; the variable mass dynamic vibration absorber is controlled according to the value of the excitation frequency omega. According to the variable mass dynamic vibration absorber control method, the effective vibration reduction frequency band of the vibration absorber can be effectively broadened, the phenomenon of resonance of the main system after the vibration absorber is installed can be eliminated, and performance of the vibration absorber is more stable. No control system or actuator needs to be additionally arranged, and the variable mass dynamic vibration absorber control method is easy to achieve and has good practical value.

The invention discloses an optical device spectrum response measurement method based on double sideband modulation and stimulated Brillouin scattering effect, comprising steps of dividing an optical carrier wave which is outputted by a light source into two paths, performing frequency-beating in a photoelectric detector by a scanning frequency double sideband signal and a carrier having the frequency shifted after the signal passes through the optical device to be detected, obtaining two radio frequency signals which have two different frequencies and carry spectral response information of the optical device to be detected at the scanning frequency double sideband signal frequency position, using a radio frequency amplitude phase extraction module to respectively extract amplitude phase information of two radio frequency signals to obtain an amplitude-frequency response and a phase frequency response of the optical device to be detected at the optical detection signal frequency, changing the wavelength of the optical detection signal and repeating the above process to obtain the spectral vector response information of the optical device to be detected. The invention also discloses an optical device spectrum response measurement device based on the double sideband modulation. Compared with the prior art, the optical device spectrum response measurement method and measurement device greatly improve the measurement range and the measurement efficiency.

The invention discloses a spectral response measurement method of an optical device and belongs to the technical field of optical measurement. According to the method, optical detection signals of the single wavelength are divided into two paths, frequency shifting with the fixed frequency shifting amount is carried out on one path of signals, and the other path of signals pass through the optical device to be detected; then frequency beat is carried out on the two paths of light, and radio-frequency signals carrying the spectral response information of the optical device to be detected at the optical detection signal frequency positions are obtained; a radio-frequency amplitude phase extraction device with the same working efficiency and the frequency shifting amount is used for extracting the amplitude phase information of the radio-frequency signals, and the amplitude frequency response and phase frequency response of the optical device to be detected at the optical detection signal frequency positions are obtained; the wavelength of the optical detection signals is changed, the process is carried out repeatedly, and the spectral vector response information of the optical device to be detected is obtained. The invention further discloses a spectral response measurement system of the optical device. Compared with the prior art, the spectral response measurement method and system of the optical device have the advantages of being capable of achieving the high-precision measurement of the amplitude frequency response and phase frequency response of the optical device and greatly lowering cost at the same time.

The invention relates to the technical field of sound boxes, in particular to a sound debugging method and device based on an amplitude-frequency response curve; the method comprises the following steps: acquiring an audio signal acquired by a microphone, generating a measurement amplitude-frequency response curve of the audio signal, and then, taking a preset standard amplitude-frequency responsecurve as a reference, debugging the measurement amplitude-frequency response curve according to an amplitude-frequency curve fitting target curve algorithm, obtaining a target amplitude-frequency response curve, obtaining corresponding DSP parameters of the target amplitude-frequency response curve, setting the DSP parameters to a sound box DSP, so as to complete debugging of the sound box in a sound system. Therefore, according to the embodiments of the invention, the sound debugging operation can be simplified, and the debugging efficiency is improved.

The invention discloses a fruit hardness nondestructive detection method and device based on laser doppler vibration measurement. The detection method comprises the following steps of: collecting representative fruits to form a modeling sample set; detecting the quality of samples; acquiring vibration signals; processing the vibration signals; detecting a hardness standard value; and establishing and testing a hardness prediction model. The detection device comprises a vibration control system and a vibration signal acquisition system. Filtering, infinitesimal analysis, FFT (Fast Fourier Transform) and amplitude frequency response are performed on output signals of a laser doppler vibration measurement controller and an ICP (Inductively Coupled Plasma) acceleration sensor by signal analysis software in a laser doppler vibration measurement module. The fruit hardness nondestructive detection method and device have the advantages of causing no damage to the detected fruits, being not affected by environmental noises, causing no harm to the free vibration of the fruits and being good in adaptability, and realizes the nondestructive detection on fruit hardness.

The invention relates to a method for designing a high-order finite impulse response digital filter, which comprises the following steps that: a neural network method is utilized and the amplitude-frequency response error sum of squares of a filter to be designed and an ideal filter serves as the calculation energy function of a neural network; the gradient descent learning algorithm is adopted to train the weight of the neural network to minimize the amplitude-frequency response error sum of squares of the filter to be designed and the ideal filter; when the neural network is stabilized, each parameter of the finite impulse response digital filter can be obtained and then the design of the finite impulse response digital filter is completed. The high-order finite impulse response digital filter designed by the method of the invention is characterized by small pass band fluctuation, large stop-band attenuation, controllable boundary frequency and high precision, etc., especially by that no matrix inversion algorithm is required to be carried out in the design, thus having fast operation speed, and the filter has broad application prospect in the engineering fields such as data transmission, high-precision televisions, radar and sonar systems and voice and image processing, etc.

The invention discloses a design method of an FIR filter based on a variable learning rate neural network, which introduces a variable learning rate algorithm to automatically adjust the value of the learning rate in the course of triangle basis function neural network training so as to improve the learning efficiency and the convergence rate of the neural network. A relative neural network model is built according to the relationship between the triangle basis function neural network and the amplitude-frequency characteristic of a linear phase 4 type FIR filter. The sum of error squares of the amplitude-frequency response of the FIR linear phase filter and the ideal amplitude-frequency response in a whole passband and a stopband is minimized. An FIR high-pass filter and a band-pass filter are designed for optimization with the method, and the result shows that the FIR filter designed by the method has availability and superiority. The designed FIR filter has the advantages of high convergence rate, no overshoot impulse and fluctuation of the amplitude-frequency passband, narrow amplitude-frequency transition band and large attenuation of the stopband.

The invention belongs to the field of spaceflight test control and communication technology and discloses a simulation method for radial time-varying electron densities of a plasma sheath of a high-speed aircraft. The method comprises the steps that steady electron densities are generated according to radial obedient double-Gaussian distribution of the steady electron densities on the aircraft; an expected frequency response matrix of a two-dimensional filter is obtained through time-varying electron densities and power spectral densities; a two-dimensional Gaussian window function is generated, windowing function processing is performed on the expected frequency response matrix of the two-dimensional filter, and an amplitude-frequency response of the two-dimensional filter is obtained; and two-dimensional Gaussian white noise is generated and subjected to filtering processing through the two-dimensional filter, radial electron density time-varying offset of the plasma sheath of the high-speed aircraft with a probability density function and the power spectral densities meeting requirements is obtained, and the radial electron density time-varying offset and the steady electron densities are superposed to obtain a time-varying plasma sheath electron density sequence. Through the method, high difficulty and high complexity of direct modeling of two-dimensional electron densities are avoided; and an electromagnetic calculation error caused by a dielectric model error is avoided.

The invention discloses a hardware trojan detection method and system based on time delay. The method comprises the following steps of firstly obtaining bypass time delay information of a chip to be detected, wherein the bypass time delay information includes an amplitude frequency response curve and/or a phase frequency response curve of each signal path of the chip to be detected; obtaining the resonance valley frequency and the resonance peak frequency of each signal path in the chip to be detected according to the bypass time delay information; finally and respectively comparing the resonance valley frequency and the resonance peak frequency of each signal path in the chip to be detected with the corresponding preset resonance valley frequency threshold and the resonance peak frequency threshold of each signal path; judging whether hardware Trojan exists in the chip to be detected or not according to the comparison result. The addition of the additional chip area for test is not needed, the workload and the test cost are greatly reduced, and the work efficiency is improved.

The invention relates to a method for measuring rigidity of poultry eggs and belongs to the field of mechanical detection of physical properties of food products. The method comprises the following steps: vertically putting a poultry egg sample to be measured on a connecting plate of a brace table of a tester, and fixedly connecting the poultry egg and the connecting plate of the brace table by adhesive; putting a mass block at the top of the poultry egg, and fixedly connecting the mass block and the poultry egg by adhesive, so that the poultry egg and the mass block constitute an unidirectionvibrating system; and starting a poultry egg rigidity measurement testing system, knocking at the center of the top of the mass block with a force hammer, transmitting a force sensor signal on the force hammer and an acceleration sensor signal on the side of the mass block to a spectroanalyzer through a signal converter, and finally working out a amplitude-frequency response function curve of thepoultry egg by the spectroanalyzer. The frequency to which the formant corresponds is the natural frequency fo of the poultry egg, and the rigidity of the poultry egg can be calculated by using a formula to calculate the poultry egg rigidity. The method measures the rigidity of the poultry egg by an instrument and provides a method for measuring basic parameters for the development of equipment for detecting, packaging, storing, transporting and processing poultry eggs.

The invention relates to an analog high-definition video transmission system. Mainly, a digital signal is embedded into an analog high-definition system, and line/field blanks and idle time/frequency spaces, which are not used by the analog high-definition system, are utilized to carry out transmission, and thus, downward compatibility can be achieved. Meanwhile, by using a digital channel estimation technology, an amplitude-frequency and phase-frequency response of a coaxial cable/twisted-pair channel can be accurately estimated, and thus, compared with the prior art of estimating a channel response only according to measurement on amplitude-frequency responses of a small number of frequency points of the channel, channel estimation accuracy of the analog high-definition video transmission system provided by the invention is obviously improved, so that adaptability to different channels and particularly poor cables is promoted.

The invention discloses a dual-degree-of-freedom dynamic vibration-damping boring bar, which includes a cutter head, a composite structure cutter bar, a dual-degree-of-freedom dynamic shock absorber, and an adjusting stud. The carbon fiber rod at the end, the adjustment stud and the metal sleeve are threaded to the front end of the metal sleeve, and the double-degree-of-freedom dynamic shock absorber is placed between the adjustment stud and the carbon fiber rod in the metal sleeve. The shock absorber is mainly composed of two groups The mass block and the shock absorbing spring form a two-stage shock absorbing system, and form two annular gaps inside which can accommodate the damping fluid. The vibrating spring applies an elastic restoring force opposite to the direction of the exciting force to the knife bar to offset part of the exciting force, thereby reducing the vibration of the knife bar. The invention can solve the cutting chatter problem of the boring bar during deep hole boring processing, has higher rigidity and natural frequency, better amplitude-frequency response characteristics, and is more suitable for deep hole processing.

The invention discloses a multi-peak-value regression estimation method for structural damages based on a reverse focusing peak value. The method comprises the following steps: carrying out a sweep frequency test on an undamaged structure to be detected by adopting an initiative stress wave detection mode to obtain a structure amplitude-frequency response curve; selecting a plurality of wave crest frequencies from the structure amplitude-frequency response curve as detection signal central frequencies; carrying out damage detection on the structure by combination of a time reversal technology and the initiative stress wave detection mode so as to obtain focusing peak values of different central frequency time reversal focusing signals in different damage states; carrying out multi-variant linear regression analysis by taking different central frequency focusing peak values as independent variables, taking the different central frequency focusing peak values measured in the different damage states as independent variable regression samples, and taking the damage states as dependent variables to obtain a regression equation of the damage states. Under the condition that testing conditions are not changed, the method can be used for estimating the current structural damage state by the plurality of different central frequency focusing peak values measured in the certain damage state according to the regression equation.

The method of sweep frequency source with restorable phase information belongs to metric testing field. It takes advantage of Hilert transform to restore its lost phase information on the basis of sweep frequency source calibrating method of broadband sampling oscilloscope, thus reconstructs step response of oscilloscope. In this method, sweep frequency source (1) outputs adjusted constant amplitude sine-wave sweep signal, oscilloscope (2) receives amplitude-frequency response of oscilloscope, then it finished the process of data in computer process (3). The processing step includes: preprocess of data of amplitude-frequency through widening frequency-field window and adding certain-amplitude noise to data of prolongation; then, it restores the phase with Hilbert transform in order to receive intact data including amplitude-frequency and phase-frequency response.

The invention provides a multipath linear isolation circuit which can be applied to measuring equipment, e.g., an oscilloscope. After linear isolation, the input signals are outputted, and input/output signals are electrically isolated. The multipath linear isolation circuit comprises a low frequency amplification circuit, a linear optical coupler circuit, a frequency compensating circuit, an intermediate frequency low pass circuit, an intermediate frequency subtraction circuit, an intermediate frequency transformer, a high frequency subtraction circuit, a high frequency transformer and an addition circuit. The input signals are divided into three parts of low frequency, intermediate frequency and high frequency and are isolated through different pathways. A low frequency signal pathway utilizes the linear optical coupler circuit for linear isolation, a frequency response compensating circuit is further added for compensating amplitude-frequency response recess caused by time delay of a linear optical coupler. For incompatible restriction of the low frequency and high frequency of transformers, frequency band width of the transformers is not very great. According to the multipath linear isolation circuit, the intermediate frequency transformer and the high frequency transformer are respectively utilized to isolate the intermediate frequency signals and the high frequency signals, so band width of the isolation circuit is greatly improved. The multipath linear isolation circuit can be conveniently applied to the measuring equipment, e.g., the oscilloscope.

The invention discloses a photoelectric detector amplitude-frequency response calibration method. A heterodyne ineterferometer is composed of a polarization beam splitter, reflectors and acoustic optical modulators; a beat frequency signal generated by the heterodyne ineterferometer serves as an excitation signal for calibrating frequency response of a photoelectric detector; and frequency shifting range, number and cascade method of the acoustic optical modulators in the heterodyne ineterferometer are configured to adjust frequency range and frequency resolution for photoelectric detector frequency response calibration. By utilizing the photoelectric detector amplitude-frequency response calibration method, the problems that the application of a light source internal modulation method is susceptible to external temperature fluctuation and the frequency resolution is low are avoided, the calibration frequency range and frequency resolution can be flexibly adjusted according to application requirements, the system is simpler, and the limitations of environment vibration and mechanical device resonance to the calibration frequency range in a photo-mechanical rotation method are avoided.

The invention provides a compensation method for unbalanced broadband intermediate frequency signal amplitudes. Intermediate frequency signals are input into an FPGA, and amplitude values of all frequency points are generated through the FPGA. A PC reads amplitude values corresponding to N1 frequency points respectively from the FPGA, and an amplitude sequence A (i) is generated. The amplitude sequence A (i) with the length of N1 is expanded to be N2 long and is normalized to obtain an amplitude sequence B (i). The B (i) is multiplied by a standard amplitude-frequency response S (i) to obtain an amplitude sequence C (i). Windowing and IFFT are carried out on the amplitude sequence C (i) through the PC, the length is N2, and N3 data in the middle are selected as a filter factor sequence h (i). The filter factor sequence h (i) is loaded into a compensation filter in the FPGA through the PC. An output signal of the compensation filter in the FPGA is a sampling sequence after unbalance amplitude compensation.

The invention provides a device and method for measuring amplitude-frequency characteristics of an electro-optical intensity modulator based on optical sampling. The device comprises a mode-locked laser, an electro-optical intensity modulator to be measured, a microwave signal source, a direct-current voltage source, a low-frequency photodetector, a spectrum analyzer and a computer. According to the device and the method in the invention, amplitude-frequency response measurement of the broadband electro-optical intensity modulator is realized by utilization of low-speed optical down-conversionsampling; because optical down-conversion sampling has the characteristics of being low in sampling rate, large in analog bandwidth and high in precision, a measurement system has the advantages of being in low-frequency detection and free from calibration of the photodetector; and in addition, compared with the existing low-frequency detection method, the measurement system only utilizes the single micro-wave signal source, and is simple in structure and relatively low in cost.

The invention discloses a method for diagnosing inter-turn insulation faults of dry type electric reactors on the basis of frequency response analysis. By the aid of the method, the problem of incapability of timely detecting inter-turn insulation breakdown and occurred inter-turn short-circuit for existing dry type electric reactors in the prior art can be solved. The method includes applying voltage signals at different frequencies to A-phase windings, B-phase windings and C-phase windings of each three-phase dry type hollow electric reactor (2) by the aid of a frequency response analyzer (9), and acquiring electric reactor impedance amplitude-frequency response characteristic curves under the condition of the various voltage signals at the frequencies; comparing the electric reactor impedance amplitude-frequency response characteristic curves acquired at the second step under the condition of the various voltage signals at the frequencies to electric reactor impedance amplitude-frequency response characteristic curves when the three-phase dry type hollow electric reactor is put into operation, and diagnosing that inter-turn short-circuit faults of the three-phase dry type hollowelectric reactor already occur if correlation coefficients of each electric reactor impedance amplitude-frequency response characteristic curve under the condition of the voltage signals at the frequencies and the corresponding electric reactor impedance amplitude-frequency response characteristic curve are smaller than 1. The frequency ranges of the voltage signals are 0-1000 thousand hertz. Themethod has the advantages that the inter-turn insulation faults are detected in advance and are handled in advance, and accordingly burning loss of the dry type hollow electric reactors can be effectively prevented.

The present invention relates to the technical field of digital signal processing, in order to automatically eliminate the overshoot of the all-phase filter without introducing iterative optimization measures, and finally generate a high-efficiency and high-performance FIR filter design method that fully realizes the analytical design in the whole process , and given to the digital signal processor to achieve. The technical scheme that the present invention adopts is, digital filter analytical design method and filter thereof, and step is as follows: Step 1. determine boundary frequency integer parameter value; Step 2. obtain a length and be the convolution window w of 2N-1 _c (n); Step 3. The parameters M, N and convolution window w _c (n) Substitute directly into the following analytical formula to obtain the filter coefficient g(n); Step 4. Calculate the Lichtenberg ratio frequency point The amplitude-frequency response at ; Step 5. Substitute T=1-(Q-1)=2-Q into the following improved analytical formula to calculate the final filter that can eliminate overshoot. The invention is mainly applied to digital signal processing occasions.

The embodiment of the invention relates to a micro-structural damping cylinder vortex-induced vibration experimental device and a simulation method. The device comprises a large wave current water tank module, a liftable support module, a gas floating platform module, a cylinder structure module, a spring module, a gas path module and a measurement module. The device can research cylinder structural vortex-induced vibration triggering and amplitude-frequency response characteristics, in particular nearly bed surface cylinder vortex-induced vibration, submarine pipeline vortex-induced vibration, the seabed scouring coupling effect and the like; and the result can provide scientific basis for an engineer to design and lay a submarine pipeline.