32results about How to "Avoid phase error" patented technology

A synthetic aperture radar polar format algorithm based on scaling principle comprises the following steps of : constructing a data collection geometric model of spotlight synthetic aperture radar; carrying out range-dimension processing pulse by pulse, inputting time-domain echo signals, subjecting the time-domain echo signals to range scaling to obtain output signals, i.e. range frequency domain signals achieving range re-sampling; processing the range frequency domain signals (scaling and focusing) to obtain an azimuth-focused image while achieving azimuth scaling (azimuth re-sampling); and subjecting the azimuth-focused data to fast Fourier transform in range dimension to obtain a two-dimensional focused image. The invention can achieve re-sampling by using two-dimensional transformation to substitute for two-dimensional interpolation in conventional PFA algorithm. The method only needs FFT and complex multiplication operation, and the computation efficiency can be improved significantly. Meanwhile, the possible phase error resulting from the finite interpolation kernel length can be obviated.

The invention discloses a circular antenna array design method for a rotation circular polarization array element to produce an OAM beam. The design method comprises the steps that 1 the antenna center frequency f is given, and the structure of a single array element is determined and optimized to generate circular polarization waves; 2 N array elements determined in the step 1 are equidistantly arranged along the circumference into an initial uniform circular array antenna; 3 feed excitation of the same phase is carried out on each array element in an initial circular array, and codirectionalrotation at a specific angle is carried out to acquire a rotated circular antenna array; and 4 the radius of the circumference of the rotated circular antenna array is adjusted, so that the field phase diagram of the rotated circular antenna array presents a spiral phase wavefront and the OAM beam is produced to acquire the final circular antenna array. According to the invention, multiple phaseshifters of different lengths are not needed; the design of a feeding network is simplified; and a phase error introduced by each phase shifter is avoided.

The invention relates to a laminated scanning based phase-difference wavefront detection and image restoration method which can be used for restoring wavefront distortions and capable of effectively restoring blurred images affected by aberrations. According to the method, a small-aperture diaphragm is moved within a pupil plane of an imaging system in a laminated scanning mode, and corresponding sub-images affected by different aberrations are recorded by using an image sensor. The recorded series of sub-images are processed by using the laminated scanning based phase-difference wavefront detection and image restoration method, and wavefront distortions of the system can be detected and the images can be restored. The method adopts the small-aperture diaphragm to perform space scanning so as to produce the sub-images having phase differences. Compared with various existing technologies for phase difference methods, the Nyquist sampling frequency is more easily met, an aberration detection range is large, out-of-focus light paths and various diffraction devices are not needed, and the laminated scanning based phase-difference wavefront detection and image restoration method has the advantages of being compact in system, convenient to use and the like.

The present invention provides a beam direction switching method and device based on a microphone array, and the method comprises the steps: determining phase delay information between microphones inthe microphone array; acquiring sound source signals collected by all microphones in the microphone array; performing beam forming of the sound source signals collected by the microphones to obtain output signals of the microphone array in the preset all beam directions; determining a target beam direction from the fixed beam directions according to the energy values of the output signals of the microphone array in the fixed beam directions; switching the beam direction of the microphone array to the target beam direction. The method can select an optimal beam direction from the preset fixed beam directions according to the position of a user, can enable the determined beam direction to adapt to the mobility of the user, and improves the applicability of the method.

The invention provides a permanent magnet synchronous motor rotor location full-order sliding mode observation device and method. The device comprises a full-order sliding mode observer, a saturationfunction processing module and a phase-locked loop module; in the method provided by the invention, an observation value as shown in description of the stator current can be output after the stator voltage us of the permanent magnet synchronous motor processed through a full-order sliding mode observer; the current error as shown in description is obtained after making the difference processing onthe value as shown in description and the stator current value is; a sliding mode function control vector F(S) is output after the value as shown in description processed through the saturation function processing module; the sliding mode function control vector F(S) in the saturation function processing module adopts a hyperbolic tangent function with adjustable boundary layer thickness, the adjusting of the boundary layer thickness is performed according to the rotating speed self-adaptive law of the switch gain gr, the counter electromotive force observation error as shown in description is obtained after the FS processed through a sliding mode gain matrix G1, the back counter observation value as shown in description is output after the value as shown in description processed througha full-order sliding mode observer; the value as shown in description is served as a state variable to be fed back to the full-order sliding mode observer to participate the update computation; a permanent magnet synchronous motor rotor location observation value as shown in description and the rotating speed observation value as shown in description are output after the value as shown in description is processed through the phase-locked loop module.

The invention discloses a rail traffic axle counting system based on FPGA phase detection. The rail traffic axle counting system comprises a first wheel sensor arranged on one side of a rail and a second wheel sensor arranged on the other side of the rail, the first wheel sensor and the second wheel sensor are connected with a control room through axle counting equipment, and the axle counting equipment comprises a first FPGA, a first conditioning circuit, a second FPGA and a second conditioning circuit. The first FPGA generates a pulse signal with the frequency f1 and sends the pulse signal to the first wheel sensor through the first conditioning circuit, and a signal returned by the first wheel sensor is connected to the first FPGA through the first conditioning circuit to be subjected to data processing. The second FPGA generates a pulse signal with the frequency f2 and sends the pulse signal to the second wheel sensor through the second conditioning circuit, and a signal returned by the second wheel sensor is connected to the second FPGA through the second conditioning circuit to be subjected to data processing. The first FPGA and the second FPGA sends the counting results to the control room. The debugging efficiency is improved, and the rail traffic axle counting system is suitable for a train travelling at a high speed.

According to the broadband CMOS second-order active balun amplifier, a series structure of two stages of active balun is used, higher phase precision is obtained, and the requirement for high loss ofa radio frequency circuit is met. Phase shift in the transmission process from a signal source to a load is eliminated through the input pi-type matching circuit, and 50-ohm input impedance matching is achieved; the first-stage active balun circuit and the second-stage output active balun circuit are in cross coupling connection through a capacitor, and the first-stage active balun circuit uses abroadband phase correction technology to obtain Vo1 and Vo2 with small phase errors and gain errors; according to the second-stage active balun circuit, two double-end-to-single-end baluns are used asoutput ends, a traditional source follower is replaced as a buffer, the phase precision is improved through phase compensation between signals, and meanwhile output matching is achieved. The invention can be used for an active balun amplifier of 1-8GHz.

The invention provides a method for measuring electrode current through an electrode current measuring device for low voltage compensation of a submerged arc furnace. The method for measuring the electrode current comprises the following steps that a Rogowski coil output signal is a differential voltage signal of primary current; a first summing integrator performs vector summing integration on the signal to obtain capacitance compensation current; a second summing integrator performs vector summing integration on the signal to obtain furnace transformation low-voltage-side current; the capacitance compensation current and the furnace transformation low-voltage-side current are sent to a first adder and subjected to vector subtraction calculation to obtain compensated current on a short net behind a low voltage compensation access point; the compensated current is sent to a second adder; and front-phase compensated current is sent to the current-phase second adder, and is subtracted from the current-phase compensated current to obtain current-phase electrode current. The method has the characteristics of accurate measurement, wide measurement range, convenience for installation and simple structure.

A circuit breaker for a low-voltage circuit is disclosed. In an embodiment, the circuit breaker includes a current conductor, assigned a measuring transducer for measuring the electrical current of the current conductor; a first filter connected to the measuring transducer; an analog/digital converter connected to the first filter; a second, high-pass filter connected to the analog/digital converter; and a digital integrator, connected to the high-pass filter and configured to determine the electrical current of the current conductor.

The invention provides a novel position sensor-free starting method for a permanent-magnet synchronous motor. The novel position sensor-free starting method comprises the following steps of S1, building a mathematical model of the permanent-magnet synchronous motor (PMMS); S2, under an ideal condition, acquiring a stator voltage equation of the projection of the PMSM on a dq axis through a statorvoltage vector equation of a two-phase winding of the PMSM under a rotating coordinate system; and S3, acquiring a voltage equation under a gamma-delta coordinate system based on a combination of thestator voltage equation and an included angle phi between a delta axis and a q axis in the PMSM mathematical model in the S1, wherein the equations are as defined in the specification. The novel position sensor-free starting method for the PMMS provided by the invention has the advantages that I/F control can be introduced at a zero speed and low speed of a motor so as to overcome the condition oflow observation accuracy of a sliding mode observer at the zero speed and low speed, and an optimization algorithm is stably switched to sliding mode control when the motor has a certain initial speed.

The invention discloses a simulation navigation satellite signal stray suppression method. According to the method, a plurality of linear feedback shift register groups are adopted, the generated jitter signal does not have a single periodicity, and the jitter is more noisy, so that the effect of improving the stray is more obvious; and the plurality of jitter sequences are added to the low levelof the phase words, the phase noise introduced by jitter is prevented from being larger than the phase error generated by quantization, and therefore the phase resolution of the signal is prevented from deteriorating.