40results about How to "Suppress phase noise" patented technology

The invention relates to an optical fiber sensing technology and provides a method and device for suppressing phase noise of a long-distance optical fiber interference system based on optical path difference matching so as to solve the problems that the input power of the existing long-distance optical fiber interference system is limited and the phase noise of the existing long-distance optical fiber interference system is increased under the stimulated Brillouin scattering effect. The device comprises a single-frequency laser, an electro-optic phase modulator, a signal source, an erbium-doped optical fiber amplifier, a transmission optical fiber, a matching interferometer, a photoelectric detector and a signal acquisition and processing device. A laser is output by the single-frequency laser and modulated by the electro-optic phase modulator to generate a multi-frequency laser, the multi-frequency laser is amplified by the erbium-doped optical fiber amplifier and input into the matching interferometer by the transmission optical fiber, and a signal is output of the matching interferometer, detected by the photoelectric detector and processed by the signal acquisition and processing device. Suppression on the stimulated Brillouin scattering effect is achieved through the phase modulation technology, the phase noise of the system is reduced through signal frequency phase modulation and interferometer optical path difference matching, and the maximum input power and sensing distance of the system are increased.

The invention discloses a double-conjugation pumping modulating signal all-optical regeneration device based on an optical frequency comb. The all-optical regeneration device comprises a pumping laser device, the optical frequency comb, a photodecomposition multiplexer, a first coupler, erbium-doped optical fibers, a second coupler, a first section of HNLF, a wavelength selective switch, a second section of HNLF and a light bandpass filter. The device can be used for phase position regeneration of various degraded QPSL signals (including DQPSK) in a high-speed optical fiber communication network, so that influence on performance of an optical communication system by phase noise is reduced, the all-optical relay transmission distance is improved, and the error rate of a receiver is reduced. The invention further discloses a double-conjugation pumping modulating signal all-optical regeneration method based on the optical frequency comb. The double-conjugation pumping modulating signal all-optical regeneration device has the advantages of being concise in structure, stable in performance, easy to operate, remarkable in regeneration effect and the like.

The invention relates to a modulator circuit of a digital transmitter, the digital transmitter and a signal modulation method. The modulator circuit comprises a first synchronous circuit and a digital modulator, wherein the first synchronous circuit comprises a first synchronous unit and a second synchronous unit, the first synchronous unit and the second synchronous unit are used for obtaining corresponding delayed signals after carrying out phase delay on a first local oscillator signal and a second local oscillator signal respectively, and carrying out phase adjustment on digital baseband signals through the delayed signals to generate a first adjusting signal and a second adjusting signal respectively, and the rising edge and the falling edge of the first adjusting signal can fall in a low-level interval of the first local oscillator signal; the rising edge and the falling edge of the second adjusting signal fall in the low-level interval of the second local oscillator signal; the digital modulator modulates the first adjusting signal through the first local oscillator signal to generate a first radio frequency signal, and modulates the second adjusting signal through the second local oscillator signal to generate a second radio frequency signal.

The invention relates to a correction method of phase noise at a multi-antennae Orthogonal Frequency Division Multiplexing (OFDM) system receiving end belonging to the wireless data-transmission field. The method places a pilot OFDM symbol every a plurality of data OFDM symbols. In the pilot symbols, the receiving end obtains a channel matrix of the current symbol as a reference channel matrix of subsequent data symbols according to a receiving signal on a pilot sub-carrier and the receiving end pilot. In the data symbols, the receiving end obtains the channel matrix of the current symbol according to the receiving signal on the pilot sub-carrier and a reservation signal at the receiving end and obtains a united matrix of a transceiving phase noise mean values by comparing the channel matrix with that of the pilot symbol. According to an estimate value of the transceiving phase noise mean values which are separated from the united matrix, a detection matrix is adjusted. The method can simultaneous estimate and correct the phase noise of the transmitting and receiving antennas, and improve the system performance.

The invention discloses a phase unwrapping algorithm based on MECKF. According to the algorithm, an embedded cubature Kalman filter modified via a Levenberg-Marquardt method, a local phase gradient estimation algorithm based on a corrected matrix beam model (AMPM) and a quantified tracking strategy are combined to unwrap a wound phase image accurately in high efficiency. The algorithm comprises the main steps that a recursion state estimation model of the phase unwrapping algorithm based on MECKF is established, and the phase gradient estimation method based on the AMPM is used to obtain phase gradient information needed by the recursion state estimation model; and the quantified path guiding graph strategy, the recursion state estimation model of the phase unwrapping algorithm based on MECKF is guided to unwrap wound pixels rapidly along a path from a high-quality area to a low-quality area till phases of all wound pixels are unwrapped. The algorithm is characterized by higher precision and robustness.

The invention provides a high-precision pilot frequency digital phase-locked loop system based on fuzzy region pulse detection. The high-precision pilot frequency digital phase-locked loop system comprises a frequency scale module, a DDS module, a signal pulse conversion module, a pilot frequency group phase coincidence point pulse module, a phase difference measuring and processing module, a voltage-controlled crystal oscillator module, a display module and a power supply module. Compared with an existing high-precision phase-locked loop, a phase discriminator is not needed, a fuzzy region pulse detection method is adopted, the resolution of phase difference measurement is greatly improved, the resolution of phase difference measurement at any moment is better than 1 ps, the synchronization precision of the phase-locked loop is greatly improved, the system structure is integrated through the FPGA technology, the development cost is reduced, the phase noise is suppressed, and the stability and reliability of the system are enhanced.

The invention discloses a microwave photon radio frequency phase shifter based on spectrum processing and a phase shifting method thereof. The phase shifter comprises a laser source, an optical modulator, an optical fiber amplifier, a spectrum processing system, a photoelectric detector and an optical coupler. The optical amplification signal of the optical fiber amplifier is incident on the diffraction grating and is separated into a plurality of reflected light rays. Different spectral components in the plurality of reflected light rays are projected on different pixel points of each row, and the same spectral components are projected on different pixel points of each column. The laser processor modulates the amplitude and phase of the spectral component and forms a plurality of beat frequency light waves. Each optical coupler synthesizes an optical carrier wave and a first-order modulation sideband in a spectrum manner to generate an optical single sideband modulation signal. The optical single sideband modulation signal is subjected to beat frequency in a photoelectric detector to generate a radio frequency signal. The phase noise of the photon radio frequency phase shifter iseffectively restrained, the photon radio frequency phase shifting function is achieved, scanning at any angle can be achieved, flexibility is high, reconfiguration is achieved, and the phase shifter is suitable for large-scale phased array radar.

The invention discloses a dual-loop compensation orthogonal signal source phase noise restraining circuit based on a lock-in amplifier. An output orthogonal component of a quarter frequency divider is connected with the input side of a phase sensitive detector, and the output side of the phase sensitive detector is connected with the input negative terminal of an integrator. The output side of a half Vos measuring circuit is connected with the input positive terminal of the integrator. The output side of the integrator is connected with the input side of a #1 low pass filter. The output side of the low pass filter is connected the negative terminal of a comparator, and the output side of the comparator is connected with the input side of a phase frequency detector. The cophase component output side of the quarter frequency divider is connected with the input side of the phase frequency detector, the output side of the phase frequency detector is connected with the input side of a #2 low pass filter, the output side of the #2 low pass filter is connected with the input side of a voltage-controlled oscillator, and the output side of the voltage-controlled oscillator is connected with the input side of the quarter frequency divider. A signal source is connected with the input side of the phase sensitive detector, the input side of the half Vos measuring circuit and the input side of the comparator. The dual-loop compensation orthogonal signal source phase noise restraining circuit compensates for the phase offset caused by phase noise, and can effectively restrain the phase noise and ensure the eddy measuring accuracy.

The invention belongs to the technical field of free space optical communication, and discloses a coherent optical wireless optical communication transmission method and system, a storage medium and equipment, and the method comprises the steps: carrying out the symbol mapping of data through three variables: a phase, a polarization state and a data symbol bit, so as to generate baseband symbol streams in X and Y polarization states; and enabling the four paths of baseband signals to be sequentially subjected to I/Q imbalance compensation, channel equalization, time sequence recovery, carrierfrequency offset compensation and carrier phase offset compensation to obtain two paths of symbol data streams corresponding to the generated baseband signals. Phase noise caused by atmospheric turbulence can be effectively suppressed, and crosstalk between polarization states in the same symbol time slot period can be effectively avoided by cross-modulating symbol information in two adjacent symbol periods in the orthogonal polarization state. Therefore, the performance of the traditional atmospheric coherent light communication system based on the PSK or QAM modulation mode can be effectively improved, and the transmission distance of the atmospheric laser communication system is expanded.

The invention discloses an optical frequency transmission device and method based on time delay. The device is composed of a local end, a transmission link and a relay end, wherein the input light signal of the local end is transmitted to the relay end through the transmission link, and the output light signal of the slave laser device of the relay end is transmitted to the local end through the same transmission link and then is reflected back to the relay end again. In the method, two paths of signal light passing through a transmission link arrive at a relay end and then are input into an optical frequency delay comparison unit to obtain a relative frequency deviation between a master laser device and a slave laser device, and the signal frequency of output light of the slave laser device is fed back and controlled by using the relative frequency deviation, so that the frequency between the light signals input from the laser device and the local end is relatively stable. According to the invention, different additional time delays are applied to the two paths of light signals to carry out frequency comparison with a traditional transmission method, so that phase noise introduced by a transmission link can be reduced; and the relay station can perform optical frequency transmission to the next link by adopting a phase compensation mode, so that cascaded optical frequency transmission is realized.

The invention discloses a clock circuit. The clock circuit comprises a first inductance-capacitance type phase-locked loop and a first annular phase-locked loop, the first inductance-capacitance typephase-locked loop is used for carrying out frequency multiplication processing on a first input clock signal to generate a first high-frequency clock signal, and the first annular phase-locked loop isused for carrying out frequency multiplication processing on the first high-frequency clock signal to generate a first target clock signal. According to the present invention, the technical problem that a clock signal with high speed, wide frequency and low jitter cannot be provided in the prior art, is solved.

The invention provides a temperature compensation accelerometer based on a polarization maintaining optical fiber double-arm heteroaxial interferometer. An all-polarization-maintaining optical fiber interferometer is adopted as a sensing light path, a sensing arm of the interferometer is welded in a staggered-axis mode to achieve double-arm different-axis interference, and optical fibers of the two sensing arms of the interferometer are sensitive to strain and temperature at the same time; a polarization maintaining optical fiber interferometer and a push-pull type mechanical vibration pickupstructure are compounded, acceleration is converted into optical fiber strain through a vibration pickup structure, and two sets of sensing systems which have different responses to temperature and acceleration at the same time are constructed in the same sensor. In the sensor, the temperature response and the acceleration response of the two sensing systems are the temperature effect difference value and the strain effect sum of the two sensing arms respectively, and under the balance interferometer, the temperature response coefficients of the two sensing systems are equal in numerical valueand opposite in symbol, and the acceleration response symbols are the same. Phase responses of the two sets of sensing systems are added, the strain response is increased while the temperature response is eliminated, and the acceleration sensitivity of the sensor is improved.

The invention provides a remote high-frequency microwave oscillation source system based on single-stage nonlinear spectrum expansion. A same DFB laser light source is adopted to generate high-speed light millimeter waves and a remote high-frequency microwave oscillation source, so that phase noise can be effectively suppressed; the adopted DFB laser has the characteristics of narrow linewidth andhigh side mode rejection ratio, and can effectively suppress intensity noise; the remote high-frequency microwave oscillation source provided by the invention is novel in generation scheme, simple and feasible, and can effectively suppress noise. The method and the system can be used as an important reference for exploring and researching a high-bit-rate optical millimeter wave system, and can provide important support for deep research in the fields of microwave photonics, nonlinear optics, optical fiber communication, optical information processing, a new generation of information technology and the like.