47results about How to "Eliminate DC component" patented technology

The invention discloses an industrial control system based on a field bus and a control network, comprising a master station, a slave station and a network communication protocol, wherein a master processor subsystem on the master station and a master communication protocol stack exchange data by double-port SRAM, and the master communication protocol stack and a slave communication protocol stack periodically and automatically communicate; the slave communication protocol stack of the slave station receives a control command sent by the master station, simultaneously can receive input terminal state information sent from other slave stations and can periodically send the input terminal state of an I/O controller to the network; the network communication protocol is coded by Manchester; in each communication period, the master communication protocol stack on the master station automatically sends an initial frame and successively sends a data frame to each slave station according to a set address sequence, and each slave station sends a response frame according to the same address sequence. The invention can effectively lower the performance requirement on the master station processor, has low cost and strengthens stability while hardware cost overhead is low.

The invention relates to a method and a device for correcting the direct current offset of a zero intermediate frequency receiver. The method comprises the following steps: (a) estimating the initial DC-OFFSET before the zero intermediate frequency receiver is switched on with a radio frequency switch, and switching on the zero intermediate frequency receiver with the radio frequency switch to receive data after obtaining the initial DC-OFFSET estimated value; (b) making use of the initial DC-OFFSET estimated value to compensate the received data; (c) estimating the initial position of a training sequence for the received data after the compensation to obtain the offset of the actual position of the training sequence relative to an expected position; (d) performing channel impulse response and DC-OFFSET joint estimation to obtain a DC-OFFSET estimated value; and (e) making use of the DC-OFFSET estimated value to compensate the DC-OFFSET of the received data. The device comprises a main control unit and a baseband processing unit, wherein the main control unit controls the baseband processing unit to perform initial DC-OFFSET estimation, then receives data to perform initial DC-OFFSET compensation, and then performs the subsequent compensation.

The invention discloses a light emitter, which comprises a current mode logic driving module, a modulator and a terminating module, the current mode logic driving module is connected with the input end of the modulator in a direct coupling mode, and the current mode logic driving module is used for generating and outputting a high-speed differential driving signal; the output end of the modulatoris connected with the input end of the terminating module in a direct coupling mode; the modulator is used for modulating an optical signal of the modulator according to the received high-speed differential driving signal to obtain a modulated optical signal and outputting the modulated optical signal; and the terminating module is used for performing far-end impedance matching on the received high-speed differential driving signal. The light emitter has the advantages of saving hardware cost, reducing direct current power consumption, reducing circuit design complexity and facilitating high-density multi-channel integrated design.

A two-freedom homodyne grating interferometer displacement measuring system based on the optical octave method comprises a grating interferometer, a measuring grating, pre-processing unit and an electric signal processing unit. The grating interferometer comprises a laser tube, a polarizing film, a polarization splitting prism, a reference grating, a refraction element and a four-passage homodyne structure. On the basis of optical grating diffraction, optical Doppler and homodyne signal processing, the system realizes displacement measurement. The grating interferometer outputs optical signals to the pre-processing unit. The optical signals are converted into electric signals and are transmitted to the electric signal processing unit. When the interferometer and the measuring grating are in two-freedom linear relative motion, the system can output two linear displacements. The measuring system realizes optical octave through the second diffraction principle, can realize sub-nanometer and even higher resolution. Homodyne signal treatment is adopted, so that the influence brought by changes of direct components and amplitudes can be eliminated. The two-freedom homodyne grating interferometer displacement measuring system has the advantages of being insensitive to environments, high in measuring precision and the like, and can improve the performance of a workpiece table when used as a lithography machine ultra-precise workpiece table displacement measuring system.

The invention discloses a voice conference audio mixing system and a voice conference audio mixing method. The voice conference audio mixing system comprises a conference audio mixing module. The conference audio mixing module comprises an input voice processing unit and an input voice audio mixing unit. The input voice processing unit is used to subtract input voice data acquired by a current frame of a voice input port of every participant by the input voice data acquired by the previous frame to acquire the input voice difference of the current frame of every participant. The input voice audio mixing unit is used for the successive superposition of every input voice difference of the current frame, and the new audio mixing value of the current frame of the participant is acquired after each superposition. The voice conference audio mixing system and the voice conference audio mixing method are advantageous in that the new input voice data input by every participant is subtracted by the voice data input by the previous frame, and a direct current component of an audio mixing result is effectively removed, and therefore distortion of conference voice signals is prevented; design is simple, occupied resources are less, and costs are low.

The invention discloses a predictive current phase-shifting control method for three-port converter half-switching period sampling. The method comprises the steps of: based on a Y-delta equivalent transformation and current ripple method, calculating the inductor current slope of a converter under different operating conditions; collecting the inductor currents at the zero point time and the midpoint time of each switching cycle, obtaining the inductor current reference value according to the PI controller, and calculating and generating the predicted shift ratio in half of the switching cycle based on the inductor current sampling value and the inductor current reference value, and updating the shift comparison after half of the switching cycle. The invention discloses the predictive current phase-shifting control method suitable for three-port converter half-switching period sampling, which can update the phase shifting ratio in real time according to the reference value of the inductor current and can effectively eliminate the direct current component in the inductor current.

The invention belongs to the technical field of micro-displacement sensors, in particular to a two-dimensional micro-displacement sensor based on a four-quadrant grating and a detector. The sensor comprises a first laser, a second laser, a first collimating lens, a second collimating lens, a movable grating, a four-quadrant grating and a four-quadrant detector. The first laser and the second laserare respectively arranged right above the first collimating lens and the second collimating lens. A movable grating is arranged below the first collimating lens and the second collimating lens. An X-axis four-quadrant grating and a Y-axis four-quadrant grating are arranged below the movable grating, and a first four-quadrant detector and a second four-quadrant detector are arranged below the X-axis four-quadrant grating and the Y-axis four-quadrant grating respectively. Four paths of signals are generated through the four-quadrant grating and the detector for difference, subsequent high-powersubdivision is facilitated, background noise and direct-current components can be eliminated, and the resolution and precision of micro-displacement detection are improved. The micro-displacement sensor is used for measuring micro-displacement.

The invention discloses a large current source for a running test of a direct-current transmission converter valve and a compensation method thereof. A No. 2 valve of a six-pulse rectifier is connected with a compensation circuit in series for load compensation, the compensation circuit is formed by connecting a series circuit and an auxiliary thyristor valve V in parallel, the series circuit is composed of a set quantity of diodes and inductors, and the purpose of compensating a three-phase unbalanced current is achieved through a set time sequence control process. According to the compensation method of the large current source for the running test of the direct-current transmission converter valve, load compensation is adopted for branch circuits with unbalanced currents in a back-to-back current source loop, the corresponding compensation circuit is arranged on the No. 2 valve, which constitutes the same phase of voltage bridge arm as that of a trial valve, so as to form a load to compensate voltage drop caused by introduction of the trial valve and the auxiliary valve, when the trial valve is cut in the entire back-to-back current source loop, direct-current components generated in a three-phase alternating-current line due to the unbalanced three-phase load are eliminated greatly, and thus, damage to a test loop and test equipment is avoided.

The invention discloses a power grid voltage rapid phase locking method with high robustness. A Clarke conversion unit, an orthogonal signal generator and a positive sequence calculation unit are used, positive sequence fundamental wave extraction under the working conditions that the power grid voltage signal contains direct current bias, imbalance and waveform distortion is realized, and then the three-phase power grid voltage is converted into a synchronously rotating direct current quantity through the Park conversion unit, and finally closed-loop control is realized through a sliding modecontroller, a correction unit and an integration unit, so that rapid extraction of the phase angle of the power grid voltage is completed. According to the method provided by the invention, various interferences contained in the three-phase power grid voltage can be eliminated in the whole phase locking process, and rapid and accurate phase locking is realized.

The invention discloses a quasi-PCI and PI combined control single-phase photovoltaic grid-connected inverter current control method in the technical field of new energy photovoltaic power generation.The method comprises the following steps of: adding a cut-off frequency into a proportional complex integral (PCI) controller to form a quasi-PCI controller; realizing a complex number field in a single-phase quasi PCI through a lag output item of a second-order generalized interactor (SOGI); taking a difference value between a given grid-connected current iref and an actual grid-connected current iL as the input of the quasi-PCI controller; taking a difference value between a grid-connected current direct current quantity reference value IL-dc and a grid-connected current direct current quantity as an input of a PI controller; and after the output of the quasi PCI controller and the output of the PI controller are added, controlling the switching-on and switching-off of an inverter switching tube through PWM modulation. According to the invention, the influence of power grid voltage fluctuation and frequency offset on the grid-connected current is suppressed, the direct-current component of the grid-connected current is eliminated, and high-quality control is realized while the design of a non-isolated photovoltaic grid-connected inverter current controller is simplified.

The invention discloses a 9B/10B coding method suitable for low-pass and band-pass channels, which is used for coding a 9-bit source sequence set into a 10-bit target sequence set, and the 10-bit target sequence set does not contain balance sequences' 1010101010 'and' 0101010101 '. The 9-bit source sequence set comprises a first type of 9-bit source sequence set, a second type of 9-bit source sequence set and a third type of 9-bit source sequence set. The first type of 9-bit source sequence set only contains 9-bit source sequences with difference values of 1 and-1, and after one-bit data '0' or '1' is inserted into the same position of each sequence in the first type of 9-bit source sequence set, the sequence is coded into a 10-bit target balance sequence; the second type of 9-bit source sequence set selectively only contains 9-bit source sequences with the difference value of 3 or only contains 9-bit source sequences with the difference value of-3, one bit of data '0' or '1' is inserted into each sequence in the second type of 9-bit source sequence set, and a pair of 10-bit target unbalanced sequences with the difference value of +/-2 is coded.

The invention belongs to the technical field of optical fiber sensing and discloses a common-path double-wavelength orthogonal phase demodulating system. The system comprises a core control board, a fast widely-tunable laser, an optical fiber circulator, a double-beam interference type optical fiber sensor, a photoelectric detector and a computer. The core control board realizes output wavelengthdriving of the laser and synchronous acquisition and transmission of data of the photoelectric detector. The widely-tunable laser can achieve thenanosecond-order wavelength switching speed; two orthogonal wavelengths are sequentially output; and two orthogonal signals for phase signal extraction are generated. The common-path double-wavelength orthogonal phase demodulating system can solve the following three main problems of an existing double-wavelength phase demodulating system, the problems includepower imbalance and crosstalk caused by double optical paths, restrictions between the doublewavelengths and the cavity length, and elimination of a direct-current component of an interference fringe. The common-path double-wavelength orthogonal phase demodulating system realizes high-speedphase demodulation of any cavity length in an optical path through fast wavelength switching, and can be widely applied to the fields of high-speed vibration sensing, acoustic sensing and the like.

The invention relates to a zero-phase on-line DC removal filter for a road noise active control system. The zero-phase on-line DC removal filter comprises a first delayer, wherein the first delayer isused for delaying an input signal x(n) by fs unit lengths to obtain a delay signal x(n-fs); a first subtracter, taking an input signal x (n) and a delay signal x (n-fs) as input and subtracting the input signal x (n) and the delay signal x (n-fs) to obtain an output difference signal w (n); a first adder, taking the difference signal w (n) and the intermediate delay signal r (n-1) as input and adding the input to obtain an intermediate signal r (n); a second delayer, used for delaying the intermediate signal r (n) by one unit length; and a first multiplier, used for dividing the intermediatesignal r (n) by the sampling frequency fs to obtain an average value of the input signal x (n), and a second subtracter, used for subtracting the input signal x (n) from the average value to obtain adirect-current-removed output signal y (n). Compared with the prior art, the zero-phase on-line DC removal filter can realize online DC component removal, does not introduce phase change, and is suitable for online removal of DC components in active noise control.

The invention discloses a noise spectrum analysis and signal-to-noise ratio optimization method for a fiber-optic gyroscope. The method comprises the following steps of: 1, demodulating by using a sine wave modulation technology to obtain a closed-loop error of a closed-loop fiber-optic gyroscope system; 2, based on the closed-loop error model, establishing a dynamic equation of the fiber-optic gyroscope by considering parameter uncertainty; and 3, designing a feedback control matrix Kc of the closed-loop fiber-optic gyroscope system, so as to enable the fiber-optic gyroscope to meet the exponential stability and to optimize the linearity and the detection precision of the fiber-optic gyroscope system under the conditions of parameter uncertainty, nonlinearity and disturbance on the premise of ensuring that the fiber-optic gyroscope has the required H infinity performance. According to the invention, the closed-loop error is modulated to high frequency so as to eliminate the influence of interference light intensity and stray light interference, the nonlinear interference effect, light intensity fluctuation and inevitable noise are considered, and a dynamic model of a closed-loop fiber-optic gyroscope system is established. Then, a robust control algorithm is designed to optimize the performance of the fiber-optic gyroscope system.