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257results about How to "Strong interference" patented technology

Method for detecting zero crossing time, frequency and phase difference of power sinusoidal signals

The invention discloses a method for detecting zero crossing time, frequency and phase difference of power sinusoidal signals. In the method for detecting zero crossing time, by using the fundamental principle that a sinusoidal signal close to the zero crossing can be approximately equivalent to a linear signal, after a zero crossing position of a signal is worked out by rough calculation, a voltage amplitude close to the signal zero crossing is counted by the unary linear regression theory so as to acquire the zero crossing time of the sinusoidal signal. The method for detecting a frequency of a zero crossing point of a sinusoidal signal comprises the following steps of: obtaining a period value of each zero crossing point by carrying out the cumulative mean on each zero crossing point phase different of the obtained signal, and solving the reciprocal to obtain the signal frequency value. The method for detecting phase difference comprises the following step of calculating the phase difference between different signals by means of a zero crossing point phase value of each different signal. The invention is insensitive to the relative position of the zero crossing point of the actual signal, can realize higher detection accuracy in the digital detection system, has a strong suppression function to the noise of the signal source and the interference, and finally ensures the application of the method in a high-accuracy detection field.
Owner:WASION GROUP HLDG

Time-domain joint estimation method for synchronizing frames, frequencies and fine symbols for orthogonal frequency division multiplexing (OFDM)

The invention discloses a joint estimation method for synchronizing frames, frequencies and fine symbols for orthogonal frequency division multiplexing (OFDM). The method comprises the following steps: carrying out autocorrelation operations of small point length and big point length on base band data sequences at the receiving terminal in parallel; jointly determining the frame synchronization position in real time and in parallel according to the small point autocorrelation peak and the big point autocorrelation peak; computing integer frequency offset coarse estimation value and decimal fraction frequency offset coarse estimation value according to the small point autocorrelation peak and the big point autocorrelation peak; estimating the final frequency offset detection value from the integer frequency offset coarse estimation value and the decimal fraction frequency offset coarse estimation value with a frequency offset dereferencing decision device; carrying out frequency offset correction on the base band data sequences according to the estimated final frequency offset detection value; and carrying out cross-correlation on the corrected base band data sequences and the local data sequences and determining the accurate fine symbol synchronization position through the cross-correlation peak. The contradiction of complex system measure function hardware design in the traditional time-domain joint estimation systems is solved by using the method.
Owner:浙江科睿微电子技术有限公司

Multiple-input-multiple-output radar waveform design method

A multiple-input-multiple-output radar waveform design method belongs to the radar communication technical field, and aims to provide a design method with lower related sidelobe and frequency spectrum inhibition depth, high efficiency, less consumption, high robustness, and excellent time frequency anti-interference performance; the method comprises the following steps: pre-evaluating an autocorrelation sidelobe inhibition fuzzy region according to a relative position between a strong scatterer and a to be measured object in a radar scene, thus forming a corresponding object function; analyzing MIMO radar waveform orthogonality constraint so as to form the object function satisfying the orthogonality constraint; pre-evaluating a frequency domain interference fuzzy frequency band zone according to scene prior information, thus forming the corresponding object function; forming a constant modulus phase coding waveform constrained condition; forming a loose alternative projection algorithm framework; solving a waveform design according to the loose alternative projection algorithm framework, thus providing three waveform optimization output modes. The loose alternative projection constant modulus waveform coding design enables the MIMO radar to have batter detection performance.
Owner:HARBIN INST OF TECH +1

Optimized cesium-light-pump weak magnetic detection device

The invention relates to an optimized cesium-light-pump weak magnetic detection device. In the optimized cesium-light-pump weak magnetic detection device, a non-magnetic-effect thermostatic controller enables a cesium spectrum lamp and a cesium sample absorbing bulb to be in the constant-temperature steam state, a radio frequency source stimulates the cesium spectrum lamp to emit light, and the light is converted into left handed circular polarization light to illuminate the cesium sample absorbing bulb, and focused on a photoelectric detector through a convex lens; a magnetoresistive sensor magnetic measuring module assists in measuring the value of a geomagnetic field of the position where the device is located, the range of strength is judged through an embedded type processing terminal module, and a self-oscillation module is controlled in a segmentation mode; photomagnetic resonance signals of the cesium sample absorbing bulb are detected by a low-noise photoelectric conversion circuit and simulate a high-frequency coil on the cesium sample absorbing bulb after being amplified and dephased so as to constitute a self-oscillation circuit, and Larmor signals are output; a Larmor signal measuring module and a big-dipper / GPS locating module are used for accurately measuring the value of the geomagnetic field of the position where the device is located. According to the optimized cesium-light-pump weak magnetic detection device, by means of the method achieving auxiliary magnetic field measurement, subband control, accurate frequency measurement and dual-mode locating, detection accuracy and reliability of the device are guaranteed.
Owner:WUHAN UNIV OF TECH

Method for identifying time-varying structure modal frequency based on time frequency distribution map

The invention relates to a method for identifying a time-varying structure modal frequency based on a time frequency distribution map. The method comprises the following steps of: 1, acquiring structural dynamic response signals of an identified structure and setting sampling time and sampling frequency; 2, performing time frequency transformation on each response signal to obtain a time frequency distribution coefficient and drawing the time frequency distribution map; 3, writing the time frequency distribution coefficient into a corresponding energy distribution form and rearranging the coefficient as a column vector; 4, determining a time frequency distribution region corresponding to the response containing each-order time-varying modal frequency for identification according to the time frequency distribution map of each response; 5, extracting parts with the highest energy time frequency distribution corresponding to the each-order time-varying modal frequency from the time frequency distribution map by using proper time frequency window functions respectively; 6, estimating the each-order time-varying modal frequency by using a weighting nonlinear least square method; and 7, performing error analysis on the identification result. The method has the advantages of clear physical significance, simple and convenient use, high applicability and high anti-interference capability.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY

Side slop optical fiber Bragg optical grating multi-point displacement sensor and using method thereof

InactiveCN104006744ARealize multi-point displacement monitoringStrong interferenceUsing optical meansSteel tubeCorrosion
The invention relates to a side slope optical fiber Bragg optical grating multi-point displacement sensor and a using method of the side slope optical fiber Bragg optical grating multi-point displacement sensor and belongs to the field of photoelectron measuring technologies. The displacement sensor comprises an upper end flange plate, an upper end elastic protection ring sleeve, an upper end pull rod, an upper end displacement spring, a protection steel tube, an elastic steel disc, optical fiber Bragg optical gratings, a lower connection leading-out optical fiber, an upper connection leading-out optical fiber, a steel tube optical fiber leading-out hole, a lower end displacement spring, lower end pull rod, a lower end flange plate and a lower end elastic protection ring sleeve. According to the relational expression between the displacement value Delta Lambda Beta of the central wavelength of the optical fiber Bragg optical gratings adhering to the elastic steel disc and the displacement L of the sensor, the displacement changes, caused by the displacement of side slope hole soil layers or cracking of rock stratums, of the measuring position are calculated. According to different monitoring requirements, different numbers of displacement sensors can be connected in series to achieve multi-point displacement monitoring in side slope holes; the optical fiber Bragg optical gratings are adopted, so that the anti-electromagnetic interference capacity and the corrosion resistance capacity are high; the structure is simple, and operation is convenient.
Owner:KUNMING UNIV OF SCI & TECH

System and method for controlling speedless sensor of permanent-magnet synchronous motor

The invention provides a system and a method for controlling a speedless sensor of a permanent-magnet synchronous motor. The system comprises a motor body unit, an inverter unit, an SVPWM (space vector pulse width modulation) unit, a first comparator, a second comparator, a first PI (proportion and integration) controller, a second PI controller, a first coordinate conversion unit, a second coordinate conversion unit, a third coordinate conversion unit and a sliding mode extended Kalman filter. A sliding mode variable structure control law is embedded in an extended Kalman filter state equation and an output equation, a digital extended Kalman filter is finally acquired through linearization and discretization, and state evaluation of reference stator current and rotator rotating speed omega r is acquired through expanded Kalman recursion; control on the speedless sensor of a permanent-magnet synchronous motor control system is realized, and real-time updating of the reference stator current under d-q coordinates is realized. By the system and the method, control on the speedless sensor of a permanent-magnet synchronous motor can be effectively realized, high-frequency chattering generated by independently applying a sliding mode variable structure for controlling is inhibited, and accurate measurement on the speed and the position of a rotor of the motor is realized.
Owner:HENAN SUDA ELECTRIC AUTOMOBILE TECH

Fiber-optic gyroscope based on single-mode single polarized photon crystal optical fiber

InactiveCN102914299AReduce zero driftEliminate Polarization CrosstalkSagnac effect gyrometersGyroscopePolarization-maintaining optical fiber
The invention discloses a fiber-optic gyroscope based on a single-mode single polarized photon crystal optical fiber. A broadband optical fiber light source emits polarized light; the polarized light enters a polarization-maintaining optical fiber coupler via a polarization-maintaining optical fiber; the polarized light is divided into two beams, wherein one beam enters a hollow head to be attenuated, and the other beam enters an optical phase modulator via a polarization-maintaining optical fiber; the light is divided into two beams by the optical phase modulator; the two beams of light are respectively output to two ends of a optical fiber sensitive ring via a single-mode single-polarization photonic crystal tail fiber in the optical phase modulator; the optical fiber sensitive ring is wound by a single-mode single-polarization photonic crystal optical fiber; the two beams of light are respectively spread clockwise and anticlockwise in the optical fiber sensitive ring; output light is returned back to the optical phase modulator to generate interference; interference light enters the polarization-maintaining optical fiber coupler to obtain an interference signal; and an optical detector detects the interference signal to obtain the rotation speed of the measurement system. According to the fiber-optic gyroscope disclosed by the invention, the polarization error of the fiber-optic gyroscope can be effectively reduced, the null shift of the fiber-optic gyroscope is reduced, and the mechanical performance and the temperature performance of the fiber-optic gyroscope are improved.
Owner:BEIHANG UNIV

Broadband online measurement sensor for DC extra-high voltage corona current

ActiveCN102662097AReduce coronaImprove high-frequency measurement performanceCurrent/voltage measurementVoltage dividersCapacitanceLow voltage
The invention relates to a broadband online measurement sensor for DC extra-high voltage corona current, which comprises an isolation electrode unit, a signal processing unit and a system power supply unit, wherein the isolation electrode unit comprises an insulated isolation sleeve, a hollow tubular long arm low-voltage electrode and a hollow tubular short arm high-voltage electrode, wherein two ends of the insulated isolation sleeve are respectively in security isolation connection with the high-voltage electrode and the low-voltage electrode in a special way; the signal processing unit consists of a sampling resistor module, a signal acquisition module, a signal conversion module and a signal transmission module; the system power supply unit comprises a storage battery pack and a charging module; and the signal processing unit and the system power supply unit are arranged in the isolation electrode unit, so that the high-accuracy integral measurement sensor can be formed. The broadband online measurement sensor solves the problems of shielding disturbance of a strong electric field between an acquired signal and an acquisition channel as well as surrounding stray capacitance, and realizes the broadband domain online measurement and the multi-point network online measurement of the DC extra-high voltage corona current.
Owner:CHINA ELECTRIC POWER RES INST +2

Fuzzy clustering analysis-based power distribution network fault line selection method

The present invention relates to a fuzzy clustering analysis-based power distribution network fault line selection method. According to the method, the ratio of the variation quantity of the active component of the zero-sequence current of each outgoing line of a power distribution network to the total variation quantity of the active component of the zero-sequence current of the outgoing lines of the power distribution network is calculated; the simulation model of the actual operation of the power distribution network is constructed; and a fault line is determined through using a clustering analysis method. When a single-phase grounding fault occurs on the arc suppression coil grounding system of a neutral point, fault characteristics are not obvious; the grounding mode of the neutral point in the power distribution network is changed, fault signals are amplified, and therefore, line selection accuracy can be improved; a bus-bar potential transformer PT and a current transformer CT are adopted to measure the zero-sequence voltage of a bus-bar and the zero-sequence current of the outgoing lines before and after a resistor is switched; the variation quantity of the active component of the zero-sequence current of each outgoing line of lines is monitored; errors brought by measurement devices such as the current transformer CT of the line can be offset; and high anti-interference performance can be realized.
Owner:CHINA PETROLEUM & CHEM CORP +1

Switch power magnetic isolation reactive circuit for feeding back output voltage error signal

The invention relates to a switch power magnetic isolation reactive circuit for a feeding back output voltage error signal. The invention provides a switch power magnetic isolation reactive circuit for a feeding back output voltage error signal, comprising an output voltage comparison unit, a magnetic isolation feedback unit and a rectifier unit, wherein the output voltage comparison unit is usedfor sampling, comparing and compensating output voltage Vout of a DC/DC switch power supply, thus obtaining an output voltage error signal; the magnetic isolation feedback unit is used for chopping the output voltage error signal obtained by the output voltage comparison unit, thus obtaining a pulse square wave signal; furthermore, the magnetic isolation feedback unit can send the signal to a primary side by a magnetic feedback transformer; the rectifier unit is used for carrying out half-wave rectifying on the pulse square wave signal obtained by the magnetic isolation feedback unit, thus obtaining feedback voltage Vfb and outputting the feedback voltage Vfb to a primary side control chip so as to realize the closed ring controlling on the output voltage. The switch power magnetic isolation reactive circuit has the benefits that a circuit is simple, few elements are adopted, the application scope is wide, and the switch power magnetic isolation reactive circuit can be widely applied to the application in which the magnetic isolation feedback is required and has strong radiation resistance and strong interference resistance.
Owner:SHENZHEN ACAD OF AEROSPACE TECH

Double SVC coordination control device

The invention relates to a control device of an electric system static var compensator (SVC), in particular to a double SVC coordination control device. The control device comprises a measuring unit, a voltage adjustor, a distributing unit, a synchronizing system, a protecting unit, an on-off input unit, an on-off output unit and a valve base electronic unit; the measuring unit is respectively connected with the voltage adjustor and the protecting unit, the voltage adjustor is connected with the distributing unit, the protecting unit is respectively connected with the distributing unit and the on-off output unit, the distributing unit is respectively connected with the on-off input unit, the on-off output unit and the valve base electronic unit, and the valve base electronic unit is connected with the synchronizing system and a thyristor control reactor (TCR). Double SVC coordination control is achieved by the adoption of one control system, TCR coordination control and gain optimization under two main transformers in the same transformer substation are achieved, and circulating switching and capacitive reactance interlocking logic of multi-group parallel-connection capacitive circuit branches or sensitive circuit branches under all sections of buses are achieved.
Owner:STATE GRID CORP OF CHINA +1
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