73 results about "Phase frequency response" patented technology

The start up performance of an ultrasonic system under zero load conditions is improved by setting a phase set point in a frequency control loop such that, at start up under zero load conditions, the phase set point intersects a point on a phase-frequency response curve which has a low positive slope. This intersection point on the phase-frequency response curve changes as the load is increased and the system Q is decreased. The controller “seeks” a target 0° impedance phase angle. The frequency of the ultrasonic generator is set to an off-resonance frequency which is lower than the resonance of any known hand piece/blade combination. In order for the drive voltage to not exceed the physical limit of the system, the drive current is set to a low level. The drive frequency is then smoothly increased in steps until the target 0° impedance phase delta is located.

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 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 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 a low-frequency-stage magnetic sensor background noise measuring method which is applicable to measuring the background noise of a low-frequency-stage magnetic sensor in a wild environment or a big shielding room. The method comprises the following steps that: response characteristics of amplitude frequencies and phase frequencies of two magnetic sensors are respectively adjusted to be accordant; the two sensors are horizontally arranged in parallel with a distance of 2-2.5m; two ends of the sensors are in parallel and level; the sensors sense identical natural horizontal field signals which belong to relevant signals; natural field signals can be eliminated by using a differentiation method; however, the background noise of the two sensors refers to an irrelevant random signal; and signal energy after the differentiation is the sum of noise energy of the two sensors. An average power spectrum of the signals after the differentiation is calculated, the average power spectrum is divided by 2 and is subjected to extraction of a root, and the background noise of a single sensor is calculated according to the output sensitivity of the magnetic sensors. The background noise of the low frequency stage magnetic sensor in a response bandwidth is accurately measured, and compared with a theoretical analysis method, the actual noise level of the magnetic sensor is relatively accurately reflected.

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.

An amplification stage and a wideband power amplifier are provided. The amplification stage includes a stage input terminal, a stage output terminal, an amplifier, an input compensation network, and in output compensation network. At the stage input terminal is received a signal which is provided via the input compensation network to the amplifier. The input compensation network filters the signal to allow a wideband operation of the amplification stage around an operational frequency. The amplified signal provided by the amplifier is provided via the output compensation network to the stage output terminal. The output compensation network configured to allow a wideband operation of the amplification stage around the operational frequency with a minimal phase shift and distortion of amplitude and phase frequency response. The wideband power amplifier includes a plurality of amplification stage combined with transmission lines or their lumped element equivalents in a specific circuit topology.

The invention relates to a digital signal processing method. The method solves the problem of unable to obtain the accurate wideband harmonic phase by using the existed technique. Based on the NTN correct technique, this invention obtains a serious wideband impulses, corrects orderly their time base aberration, uses average signal shift to eliminate co-modulate interference, corrects mismatch aberration, and signal dithering. Then phase-spreading and eliminating linearization against the obtained phase frequency response function obtains the harmonic phase. Finally, the phase uncertainty can be obtained by means of introducing the error spread formulation and assumption verification estimation in the complex frequency area. The wideband phase obtained by this invention can be used in the phase correction in large-signal network analyzer and hi-speed sampling oscilloscope.

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 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 device and a method for measuring the frequency response of an optical device. The device comprises a laser source, a detection optical path, a reference optical path and a sampling processing module, wherein the laser optical source is used for generating a continuous laser carrier; the detection optical path is used for modulating the laser carrier to generate a first optical frequency comb, so that the first optical frequency comb obtains a detection optical comb through the optical device to be detected, and thus the amplitude-frequency response and the phase-frequency response of the optical device to be detected are recorded on comb teeth of the detection optical comb, and the detection optical comb is accordingly converted into a baseband detection signal; the reference optical path is used for modulating the laser carrier to generate a second optical frequency comb, so that the second optical frequency comb is converted into a baseband reference signal; the sampling processing module is used for sampling according to the baseband detection signal and the baseband reference signal, and calculating the amplitude-frequency response and the phase-frequency response of the optical device to be detected. According to the device and the method provided by the invention, the measuring speed is ensured while the measuring precision and the bandwidth are ensured, and meanwhile, the amplitude-frequency and phase-frequency responses of the device to be detected can be obtained.

The invention provides a phase-frequency calibration system and method of a current sensor. A voltage and current signal source outputs a first voltage signal and a first current signal in the same phase and frequency; the current sensor to be calibrated outputs a measuring current signal in response to the first current signal; a voltage and current measuring instrument samples the first voltagesignal and the measuring current signal; an input signal, namely a sampling signal of the first voltage signal, and an output signal, namely, a sampling signal of the measuring current signal are fitto obtain a transfer function of the current sensor to the calibrated; the transfer function is converted into a frequency characteristic function, and further transformed to obtain a phase-frequencyresponse function; and the frequency of the measured measuring current signal is substituted into the phase-frequency response function to obtain a phase delay angle of the current sensor to be calibrated, and the current phase of the current sensor to be calibrated is calibrated. The technical problem that a phase error is introduced into the measuring current of the current sensor of a power measuring instrument and further the current pahse measuring precision and power measuring precision are not sufficiently high is solved.

The invention provides an ultra-wide-band complex-format vector modulation error correction method based on two-stage predistortion. A loop comprises a standard signal generation module, a first-stage predistortion error compensator, a second-stage predistortion error compensator, an origin offset compensator, a transmission channel and a vector modulator; the first-stage predistortion error compensator offsets an amplitude-phase frequency response fluctuating feature of a broadband vector modulator error reversely in a molded filter predistortion manner; the second-stage predistortion error compensator corrects a modulation error, with the broadband feature, after first-stage predistorion balancing in the whole work waveband, namely, the positive-angle error with I/Q gain imbalance and gain imbalance; and the origin offset compensator corrects a modulation error with a narrowband feature, namely carrier wave leakage, via an analog device. According to the invention, the vector modulation error with the broadband feature is corrected in a digital predistortion manner, and the broadband complex-format vector modulation error is corrected effectively.

In a method for correcting amplitude and phase offsets in a sigma-delta modulator having a loop including an integrator with a filter and an amplifier, an analog-to-digital converter, a digital-to-analog converter, and an adder-subtractor, an open-loop amplitude/phase frequency response of the modulator is estimated digitally. A phase offset value and an amplitude offset value are calculated by comparing the estimated open-loop amplitude/phase response with a reference amplitude/phase frequency response. The phase and gain offsets of the loop are then compensated for according to the estimated offset values. A sigma-delta modulator implements the method.

The invention relates to a VLBI baseband signal decimal delay simulation method, comprising steps of establishing an ideal time delay system, adopting an Farrow structure filter group to constitute a finite impulse response system in order to approximate the ideal time delay system, and inputting the VLBI baseband signal into the finite impulse response system in order to generate a simulation signal having the decimal time delay amount. On one hand, the VLBI baseband signal Decimal delay simulation method enables the whole processing process to be proceeded in the time domain, prevents the multiple conversion calculations between the time domain and the frequency domain, and effectively improves the processing efficiency through reasonably designing the coefficient of the Farrow structure filter, and, on the other hand, the VLBI baseband signal Decimal delay simulation method can well process the conditions where the time delay is dramatically changed and is stable on the premise that only little initial calculation is added, and guarantees that the amplitude-frequency and the phase frequency response are not distorted.

The invention provides a high precision medium voltage distribution line true equivalent model and a parameter calculation method thereof. The model comprises A phase impedance used for simulating the self-impedance and mutual impedance of an A-phase wire, B phase impedance used for simulating the self-impedance and mutual impedance of a B-phase wire, C phase impedance used for simulating the self-impedance and mutual impedance of a C-phase wire, and G impedance used for simulating the earth return and interphase parameters. According to the invention, based on the power system analysis theory and according to the engineering practice of a distribution line, the influence of the transmission wires, among the wires and among the wires, the earth and the earth return and other factors are taken into account; an inverse-pi-shaped four-capacitor G impedance model structure is creatively provided to precisely simulate electromagnetic coupling among the wires and among the wires, the earth and the earth return; positive sequence and zero sequence parameters of the line are precisely simulated; and the cascade structure of multiple groups of lumped-parameter elements is used to meet the equivalent simulation of the distribution line of amplitude-frequency and phase-frequency response precision in a high frequency range.

The embodiment of the invention provides a multi-band wireless channel measurement calibration method and system. The method comprises the steps of establishing a single-path calibration channel, and performing single-path calibration channel measurement of N continuous bands, wherein the N is more than or equal to 1; obtaining the amplitude-frequency response of each band, and obtaining amplitude calibration data through amplitude-frequency calibration processing; obtaining the phase frequency response slope of each band, and obtaining sampling error calibration data according to the phase frequency response slope; obtaining the non-linear phase in each band, and obtaining non-linear phase calibration data through non-line phase calibration processing; measuring a practical channel through adoption of the N continuous bands, thereby obtaining the frequency domain response of each band of the actual measurement channel; and calibrating the frequency domain response of each band of the actual measurement channel according to the amplitude-frequency calibration, the sampling error calibration data and the non-linear phase calibration data. According to the method and the system, on the premise of not increasing hardware costs, the measurement bandwidth is multiplied, and the higher delay resolution is obtained.

The invention discloses an MLP method for strong nonlinear vibration of a hyperelastic cylindrical thin shell, and belongs to the field of material analysis. The invention aims to solve the problem ofstrong nonlinear vibration when the inner surface of a thin-wall cylindrical shell made of incompressible hyperelastic materials is subjected to radial simple harmonic excitation. Technical point comprises: obtaining a nonlinear differential equation set describing large-deflection vibration of the cylindrical shell on the basis of a Donnell nonlinear shallow shell theory, a Lagrange equation anda small strain hypothesis; simplifying the nonlinear equation set into a strong nonlinear Duffing equation containing large parameters based on a degree-of-freedom condensation method; obtaining a corresponding amplitude-frequency and phase-frequency response curve by utilizing proper parameter transformation and an improved MLP method. The effect is that the material has a hardening behavior dueto geometrical nonlinear characteristics caused by large-deflection vibration, and the nonlinearity of the hyperelastic material can cause a softening effect.

The invention provides a detector tester based on a Goertzel transform algorithm and a test method. The method includes: directly reading a stored standard sinusoidal signal look-up table by employing the direct memory access (DMA) technology of a single-chip microcomputer, generating sinusoidal signals with the required frequency, and improving the measuring range and the accuracy of a parameter test of a detector through a current source structure with low harmonic distortion and high spectrum purity; measuring parameters of the detector by regarding digital sinusoidal frequency-sweeping signals as input, and directly measuring characteristics of the amplitude-frequency response and the phase-frequency response; and measuring real characteristics of the low frequency response of the detector through frequency spreading of the detector by employing a feedback circuit. According to the test technology of the detector, the test range is large, the precision is high, test indexes are reliable, the test speed is fast, and portability is achieved.

The invention discloses a method for ADC phase frequency response testing. The method comprises the steps of measuring frequency reduction conversion delay time of an analog frequency mixer and a low-pass filter (MLPF) to a specific carrier frequency narrow bandwidth frequency modulation (FM) signal based on a high-definition oscilloscope (HDO) and a phase expansion sine approximation method (PUSAM); determining a required effective sampling frequency in acquiring the FM signal by an ADC based on an Nyquist sampling theorem, a bandpass sampling theorem and a protective bandwidth, thereby ensuring an effective frequency spectrum array of the FM signal; acquiring a high-carrier-frequency FM signal and a low-carrier-frequency FM signal before and after MLPF frequency reduction conversion by the ADC by an effective sampling frequency, realizing demodulation of an acquired FM signal based on PUSAM, correcting the modulated signal initial phase of the low-carrier-frequency FM signal by meansof the measured analog MLPF frequency reduction conversion delay time, and calculating the phase frequency response of the ADC in the high-carrier-frequency through the modulated signal initial phaseof two FM signals after correction. The method can accurately and quickly realize ADC phase frequency response testing and furthermore has advantages of simple testing process, wide frequency range with frequency which can be higher than the highest sampling frequency of the ADC, and multichannel simultaneous testing.

The invention discloses a frequency characteristic testing method based on electric field force excitation and an optical tweezers system. The method comprises the steps that sinusoidal voltage is applied to the optical tweezers system, and if micro-nano particles move, the micro-nano particles are electrified; if the micro-nano particles do not move, the micro-nano particles are electrified through an air ionization method, the electrified micro-nano particles generate displacement, and the input amplitude and the input phase are obtained; sinusoidal electric fields with different frequencies are applied to the charged micro-nano particles, a plurality of output amplitudes and output phases are obtained, a plurality of normalized amplitude-frequency response values and phase-frequency response values are calculated, a curve is drawn, amplitude-frequency response characteristics and phase-frequency response characteristics are obtained, and then the frequency characteristics of the optical tweezers system are tested. Correlation double beams in the optical tweezers system are converged through two focusing lenses to form an optical trap, and a micro-nano particle is stably captured at the center of the optical trap. The frequency spectrum of the optical tweezers system is generated by particle movement, and the method is used for precisely measuring the frequency characteristic of the optical tweezers system in the whole working frequency range.

The invention discloses a method for acquiring a kinetic parameter of a helicopter hub center. The method for acquiring the kinetic parameter of the helicopter hub center comprises the following steps: step 1, establishing a helicopter finite element model including a helicopter rotor and an airframe; step 2, setting a calculation frequency bandwidth, performing modal analysis on the helicopter finite element model, and acquiring frequency response data of the overall mode; step 3, performing kinetic characteristic response simulation calculation on the hub center to obtain frequency response data of the hub center, and drawing an amplitude-frequency response curve and a phase-frequency response curve based on the frequency response data of the hub center and the frequency response data of the overall mode; and step 4, acquiring the kinetic parameter of the helicopter hub center. The method for acquiring the kinetic parameter of the helicopter hub center can provide a parameter for preliminary design phase analysis of helicopter ground resonance.

The invention discloses a 1-bit digital coding metamaterial antenna unit, which comprises a first substrate and a second substrate, and is characterized in that the upper surface of the first substrate is provided with a metal layer, a grounding layer is arranged between the lower surface of the first substrate and the upper surface of the second substrate, and the lower surface of the second substrate is provided with a bias circuit layer; via holes are correspondingly formed in the grounding layer and the first substrate respectively, the metal layer penetrates through the via holes throughconductive components to be connected with the bias circuit layer, and the metal layer is connected with the grounding layer through a diode; the grounding layer is grounded; and the conductive part comprises a horizontally-arranged non-uniform transmission part and a vertically-arranged conductive rod. According to the invention, the non-uniform transmission part is designed to change the propagation path of electromagnetic waves, thereby achieving the regulation and control of the metamaterial phase. Through structural parameter optimization, the function of broadening the phase-frequency response bandwidth is realized on the premise of ensuring other performances of the antenna.

The invention discloses a water acoustic channel phase-frequency response correction method based on a RAM model. The method comprises the following steps of: (1) setting marine environmental parameters, simulating upper and lower limits of the frequency and a frequency resolution, transferring a RAM model to calculate frequency response at each frequency sampling point, and setting a variable k initial value as 2; (2) constructing a water acoustic channel phase-frequency response original value sequence; (3) calculating a stepping prediction value from a frequency sampling point 0 to a frequency sampling point 1; (4) solving a phase correction value of the frequency sampling point 1 according to the phase original value and the stepping prediction value of the frequency sampling point 1;(5) calculating the stepping prediction value of the sampling point k according to the phase correction values of the frequency sampling points k-2 and k-1; (6) solving a phase correction value of thefrequency sampling point k according to the phase original value and the stepping prediction value of the frequency sampling point k; and (7) repeating the steps (5) and (6) until phase correction ofall the frequency sampling points is completed so as to construct a phase correction value sequence of the water acoustic channel phase-frequency response.