36results about How to "Avoid phase noise" patented technology

The invention discloses a method for measuring an electro-optic phase modulator modulation factor, and relates to the technical field of the photoelectronic technique. In order to solve the problems that phase modulation signals cannot be directly detected on a photoelectric detector and nonlinearity cannot be omitted in PM-IM and FM-IM conversion processes, an optical fiber interferometer is adopted as a measuring device and composed of a beam splitter, an electro-optic phase modulator to be measured, an acousto-optic frequency shifter, an auxiliary electro-optic phase modulator and a beam combiner, wherein the electro-optic phase modulator to be measured is arranged on one interference arm of the optical fiber interferometer, the acousto-optic frequency shifter and the auxiliary electro-optic phase modulator are placed on the other interference arm of the optical fiber interferometer, and sinusoidal signals with different frequencies are loaded to the electro-optic phase modulator to be measured, the acousto-optic frequency shifter and the auxiliary electro-optic phase modulator respectively. Frequency response of the photoelectric detector is eliminated by setting a frequency relation of the loaded sinusoidal signals, self-calibration measurement is achieved, measuring accuracy of the electro-optic phase modulator modulation factor is improved, and the method has good application value.

The invention provides a frequency response measuring device and method of a high-speed photoelectric detector, and the frequency response measuring device and method of the high-speed photoelectric detector are used for solving the problem that an existing frequency response test of the high-speed photoelectric detector is not accurate. The frequency response measuring device comprises a first signal source, a second signal source, a third signal source and an optical fiber interferometer. The optical fiber interferometer is composed of a beam splitter, a polarization controller, a phase modulator, an acousto-optic frequency shifter and a beam combiner. The polarization controller and the phase modulator are connected with one interference arm of the optical fiber interferometer in series. The acousto-optic frequency shifter is placed on the other interference arm of the optical fiber interferometer. The beam splitter and the beam combiner are connected to the two ends of the two interference arms respectively in series. A light path of the beam splitter is connected with a laser. A light path of the beam combiner is connected with the high-speed photoelectric detector to be detected. The high-speed photoelectric detector to be detected is in circuit connection with a sampling circuit used for recording and analyzing. The first signal source and the second signal source are in circuit connection with an electrode of the phase modulator through a combiner. The third signal source is electrically connected with the electrode of the acousto-optic frequency shifter.

The invention discloses a coherent radar target echo signal simulating method. The method comprises the following steps of: attenuating and directionally coupling a dominant oscillation signal sequentially and performing Doppler frequency modulation to obtain a simulative target speed signal; performing state conversion between a trigger pulse of a radar emitter and the simulative target speed signal and processing a conversion result into an initial pulse; processing another trigger pulse, which is subjected to the state conversion, of the radar emitter into a resetting pulse; processing theinitial pulse to form a delay interval and a stop pulse; and performing a remainder computation on the delay interval, the stop pulse and the resetting pulse and outputting the delay interval, the stop pulse and the resetting pulse in a delayed way. The invention also discloses a coherent radar target echo signal simulating device. The coherent radar target echo signal simulating device realizes the attenuation, coupling and Doppler frequency modulation of the dominant oscillation signal and a simulative coherent radar target echo signal is obtained in the absent of a microwave source; the circuit of the device is simple; the target distance parameter simulating scope is large; and the precision is high.

The invention provides a sigma-delta PLL frequency measuring circuit and method. The circuit comprises a rectifying circuit, a phase discriminator, a loop filter, an ADC and a delay link which are sequentially arranged from the input end. The output end of the delay link is fed back and input to the phase discriminator through a counter. The frequency measuring method comprises the steps that after the rectifying circuit filters and amplifies a signal to be detected, the signal to be detected is converted into a square signal with the frequency same as that of the signal to be detected; the phase discriminator measures the zero crossing point time difference of the square signal and an output signal of the counter, and a pulse current signal with the output area and the time in a direct proportion; after the integration and the filtering are carried out on an output current of the phase discriminator through the loop filter, the output current is converted into a voltage signal; the ADC converts analog voltage output by the loop filter into a digital signal; the delay link delays the digital signal output by the ADC, and therefore the frequency of the signal to be detected is determined; a counter output signal with the clock period and the delayed digital signal in a direct proportion is generated by the counter, and is output to the phase discriminator. The anti-noise capacity is strong in the process of measuring the frequency, the resolution ratio is high, and the frequency measurement can be achieved easily.

An ultrashort pulse carrier-envelope phase detection device comprises an ultrashort pulse laser of a fixed repetition frequency, a michelson interferometer, an optical beam splitter, a first optical filter, a first photoelectric detector, a first electrical frequency doubling unit, a second optical filter, a second photoelectric detector, a second electrical frequency doubling unit, and an electrical frequency mixing and filtering unit. The ultrashort pulse laser, the michelson interferometer and the optical beam splitter are in light path connection in order. The first optical filter, the first photoelectric detector, and the first electrical frequency doubling unit with a multiple of (p-1) are connected with a first output end of the optical beam splitter. The second optical filter, the second photoelectric detector, and the second electrical frequency doubling unit with a multiple of p are connected with a second output end of the optical beam splitter. The electrical frequency mixing and filtering unit is connected with output ends of the first electrical frequency doubling unit and the second electrical frequency doubling unit. The modes of time domain time delay and frequency domain selection are adopted, front and back pulses delayed for a certain period are subjected to coherent detection with the michelson interferometer, two different frequency windows are used for frequency domain selection, signals representing carrier-envelope phase jitter are extracted, and measurement of the ultrashort pulse carrier-envelope phase signals are achieved by electrical frequency doubling and frequency mixing processes.

The invention discloses an optical generation method of a dual-band phase-coded signal, and relates to the technical field of microwaves and the technical field of optical communication. The method is shown in a figure 1 in the specification, and comprises a laser device LD, a dual-polarization quadrature phase shift keying modulator DP-QPSK, a polarization controller PC, a polarization beam splitter PBS and a balanced photoelectric detector BPD. A baseband phase coded signal is modulated to an optical carrier through an X-DPMZM in the DP-QPSK, and a local oscillator signal generates positive and negative first-order optical sidebands through a Y-DPMZM in the DP-QPSK; the PC is adjusted, the included angle between the polarization state of the DP-QPSK output optical signal and the PBS main shaft is controlled, and then a phase coding signal can be obtained after photoelectric balance detection. According to the invention, dual-band phase-coded signals can be simultaneously generated. Not only is the electronic bottleneck of the electric field technology overcome, but also the working bandwidth is expanded; and due to the dual-band characteristic, the system has potential application value in a dual-band radar.

Provided are a calibration method based on dual-transmitting dual-receiving phase measurement and distance-measuring device, the calibration method comprising: step 1, forming an external optical path; step 2, forming an internal optical path; IN step 3, conducting a phase comparison between the second part of signals of the internal and external optical paths sequentially received by a second receiving device and the first part of signals of the internal and external optical paths sequentially received by a first receiving device, outputting two-way phase signals with part of a base reference being eliminated, conducting phase comparison again between the two-way signals with part of the base reference being eliminated, and outputting the final phase signal with the base reference being eliminated. The distance-measuring device comprises a transmitting device (1, 301, 403, 502), a first reflective surface (2, 302, 402, 503), a first receiving device (3, 506), a first filter (4, 304, 405, 504), a second filter (5, 305, 406, 505), a second receiving device (8, 507), and a phase detector (307, 411, 509). The calibration method and distance-measuring device realizes phase compensation and calibration, avoids introducing uncertain phase noise into a circuit due to environmental changes, improves distance-measurement precision, and reduces system costs.

A PLL system includes: an input end; an output end; a first PFD; a first CHP connected to the first PFD; a first LPF connected to the first CHP; a first VCO connected to the first CHP and the first LPF; a second PFD connected to the first VCO; a second CHP connected to the second PFD; a second LPF connected to the second CHP; a second VCO connected to the second CHP and the second LPF; a first DIV connected to the first PFD and the second VCO; and a second DIV connected to the second PFD and the second VCO. A working method of the PLL system is also provided, which can restrain input noise as well as phase noise of the second VOC in such a manner that noise of the PLL system is well restrained.

The invention relates to a vibration monitoring system based on a double fiber grating array, which is characterized in that a narrow linewidth laser, a pulse light modulator, a pulse light amplifierand an optical filter are connected in order, an output terminal of the optical fiber is connected with a first communication terminal of a circulator, a second communication terminal of the circulator is connected with a front first communication terminal of a coupler, a back first communication terminal of the coupler is knotted and out of service, a third communication terminal of the circulator is connected with a first signal input terminal of an embedded signal processor, a front second communication terminal of the coupler is connected with a second signal input terminal of the embeddedsignal processor, a front third communication terminal of the coupler is connected with a third signal input terminal of the embedded signal processor, a back second communication terminal of the coupler is connected with a first optical fiber of the double fiber grating array, and a back third communication terminal of the coupler is connected with a second optical fiber of the double fiber grating array. The vibration monitoring system can restore vibration signals more authentically without increasing the hardware cost.

The invention discloses a laser-based wireless frequency transmission system and a transmission device and a transmission method thereof, and belongs to the technical field of frequency synchronization. The system comprises a transmitting end and at least one receiving end; the receiving end comprises a beam return unit for reflecting received partial laser signals back to the transmitting end; and the transmitting end further comprises at least one pair of third beam expanders and a phase compensation unit, wherein the third beam expanders are used for coupling the laser signals returned by the receiving end to the phase compensation unit, and the phase compensation unit is used for carrying out phase comparison on a reference frequency signal and a microwave signal modulated in the lasersignals reflected back by the receiving end in real time, and adjusting the phase of the laser signals according to a phase error. According to the laser-based wireless frequency transmission systemprovided by the invention, an active phase compensation link is introduced, so that the phase fluctuation caused by atmospheric turbulence, vibration and temperature fluctuation is suppressed, and thefrequency synchronization accuracy and reliability of a free space are improved.

The invention discloses an optical generation method of a double-frequency-band and multi-phase phase coded signal with an adjustable frequency multiplication factor, and relates to the technical fields of microwaves and optical communication. The method is as shown in figure 1 in the specification, and a laser LD, a dual-polarization quadrature phase shift keying DP-QPSK modulator, a polarizationmodulator PolM, a polarization controller PC, a polarization beam splitter PBS and a balance photoelectric detector BPD are included. A local oscillator signal is used to modulate an optical carrierthrough theDP-QPSK modulator, and after thePC is regulated, one sideband and the polarization state of the optical carrier are mutually orthogonal with the polarization state of the other sideband, two arms of thePolMare entered respectively and subjected to phase modulation opposite to a phase encoding signal; and the second PC is regulated, and a phase encoding signal is output after photoelectric balance detection. According to the invention, dual-band and multi-phase phase coded signals can be generated at the same time, and the frequency multiplication factor is adjustable. Not only is anelectronic bottleneck of an electric domain technology overcome, but also the working bandwidth is expanded, and a potential application value in a dual-band radar is achieved.

The invention discloses a frequency synthesizer based on a switched capacitor array temperature compensation circuit. The circuit comprises a phase frequency detector, a charge pump, a loop filter, avoltage-controlled oscillator, a driver, a frequency divider and an automatic frequency calibration digital circuit and a temperature compensation circuit, the phase frequency detector identifies thephase difference between the reference clock frequency and the frequency division clock output by the frequency divider; the charge pump converts the phase difference into a corresponding current, thecurrent passes through the loop filter to obtain a corresponding control voltage for controlling the frequency of an output signal of the voltage-controlled oscillator, and the output signal of the voltage-controlled oscillator also passes through the driver to serve as an output signal and is sent to the frequency divider to form a negative feedback loop; the automatic frequency calibration digital circuit is used for selecting an appropriate sub-band for the voltage-controlled oscillator and outputting a sub-band control signal; and the temperature compensation circuit is used for adjustingthe temperature compensation switched capacitor array through the comparator and the digital circuit according to the output signal of the loop filter so as to adjust the output signal of the voltage-controlled oscillator.

The invention discloses a multi-band linear frequency modulation signal generation method capable of flexibly selecting frequencies, and relates to the technical field of microwaves and the technical field of optical communication. The method is shown in a figure 1 in the specification, and comprises a laser device LD, a dual-polarization binary phase shift keying modulator DP-BPSK, an arbitrary waveform generator AWG, an erbium-doped fiber amplifier EDFA, a polarization controller PC, a polarizer POL and a photoelectric detector PD. Phase modulation is carried out on a local oscillator signal through the DD-MZM1 of the DP-BPSK upper arm, and carrier suppression double-sideband modulation is carried out on an IF-LFM signal through the DD-MZM2 of the DP-BPSK lower arm; the PC is adjusted, the phase difference between the two polarization states is controlled, and then a multiband linear frequency modulation signal can be obtained after POL and photoelectric detection. According to the invention, the electronic bottleneck of the electric field technology is overcome, and the characteristic of flexible frequency tuning is added; multi-band signals are generated at the same time, so that the system has potential application value in a multi-band radar and a distributed radar system.

A synthesizer including an oscillator for outputting an oscillation signal based on an output signal from a comparator, a frequency divider for dividing a frequency of an output signal from the oscillator based on control from a controller, and a temperature sensor for detecting an error between a preset frequency and a frequency based on a reference oscillation signal. The comparator compares an output signal from the frequency divider with an output signal from a MEMS oscillator and outputs a signal indicating the comparison result to the oscillator. The controller changes the frequency division ratio of the frequency divider based on an output signal from the temperature sensor and changes the frequency division ratio in a state in which the frequency division ratio is kept at the past value. Thus, phase noise deterioration in the synthesizer can be suppressed.

The invention relates to an orthogonal polarization modulated light-light 2-4 level coding conversion method and system based on a semiconductor optical amplifier. The method is that two 2-level light intensity modulated signals are orthogonal polarization combined and reversely or co-directionally inputted into the SOA together with the modulated signal light to achieve the 4-level intensity modulated coding conversion of the signal light. The system is that 2-level light intensity modulated signals are respectively connected into an optical orthogonal polarization coupler through a polarization controller, and then reversely or co-directionally connected into the SOA together with the modulated signal light through a polarization controller; the modulated optical signal is connected into the SOA through a polarization controller; the light outputted by SOA outputs a 4-level modulated signal through an optical filter. The invention simplifies the complexity of the system and directly outputs linearly polarized light, which achieves equidistant spacing power output by adjusting the modulation signal power ratio and realizes dynamic output range adjustment by regulating the work current of the SOA.

The invention discloses a frequency synthesizer based on a digital temperature compensation circuit. The circuit comprises a phase frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator, a driver, a frequency divider and a temperature compensation circuit, the phase difference between the reference clock frequency Fref and the frequency division clock output by the frequency divider is identified by the phase frequency detector; the charge pump converts the phase difference into a corresponding current; the current passes through a loop filter to obtain a corresponding control voltage Vtune for controlling the frequency of the voltage-controlled oscillator; wherein an output signal of the voltage-controlled oscillator passes through the driver circuit to serve assystem output and is also sent to the frequency divider to form a negative feedback loop, and the temperature compensation circuit further comprises a temperature compensation varactor, a resistancevoltage division network, a comparator, a digital circuit, a digital-to-analog converter and a low-pass filter.

The invention discloses a frequency synthesizer based on a digital temperature compensation circuit. The circuit comprises a phase frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator, a driver, a frequency divider and a temperature compensation circuit, the phase difference between the reference clock frequency Fref and the frequency division clock output by the frequency divider is identified by the phase frequency detector; the charge pump converts the phase difference into a corresponding current; the current passes through a loop filter to obtain a corresponding control voltage Vtune for controlling the frequency of the voltage-controlled oscillator; wherein an output signal of the voltage-controlled oscillator passes through the driver circuit to serve assystem output and is also sent to the frequency divider to form a negative feedback loop, and the temperature compensation circuit further comprises a temperature compensation varactor, a resistancevoltage division network, a comparator, a digital circuit, a digital-to-analog converter and a low-pass filter.

The invention relates to a time domain direct wave suppression method for a transmitting-receiving split short-wave over-the-horizon radar. The invention relates to the time domain direct wave suppression method for the transmitting-receiving split short-wave over-the-horizon radar. The invention aims to solve the problem that the direct wave suppression effect of the existing method is poor. The method comprises the following steps: 1, obtaining an echo signal; 2, reconstructing an ideal reference signal; 3, direct waves are extracted from the multi-channel echo signals through the DBF; 4, performing short-time Fourier transform on the reconstructed ideal reference signal to form a filtering template, performing short-time Fourier transform on the direct wave signal, filtering by adopting the filtering template to obtain a filtering result, and performing short-time Fourier inverse transform reconstruction on the filtering result to obtain a time domain reference signal; and 5, taking the obtained time domain reference signal as a reference signal of an adaptive filter, and carrying out direct wave suppression on the echo signal to obtain the echo signal after direct wave suppression. The method is applied to the field of short-wave beyond-visual-range radar signal processing.

The invention discloses a coherent radar target echo signal simulating method. The method comprises the following steps of: attenuating and directionally coupling a dominant oscillation signal sequentially and performing Doppler frequency modulation to obtain a simulative target speed signal; performing state conversion between a trigger pulse of a radar emitter and the simulative target speed signal and processing a conversion result into an initial pulse; processing another trigger pulse, which is subjected to the state conversion, of the radar emitter into a resetting pulse; processing theinitial pulse to form a delay interval and a stop pulse; and performing a remainder computation on the delay interval, the stop pulse and the resetting pulse and outputting the delay interval, the stop pulse and the resetting pulse in a delayed way. The invention also discloses a coherent radar target echo signal simulating device. The coherent radar target echo signal simulating device realizes the attenuation, coupling and Doppler frequency modulation of the dominant oscillation signal and a simulative coherent radar target echo signal is obtained in the absent of a microwave source; the circuit of the device is simple; the target distance parameter simulating scope is large; and the precision is high.

The invention discloses a method for measuring the modulation coefficient of an electro-optical phase modulator, and relates to the field of optoelectronic technology. The invention aims to solve the problem that the phase modulation signal cannot be directly detected on a photodetector and the non-linearity in the conversion between PM-IM and FM-IM cannot be avoided The problem of the process, the present invention adopts the optical fiber interferometer as the measuring device, the optical fiber interferometer is composed of a beam splitter, an electro-optic phase modulator to be tested, an acousto-optic frequency shifter, an auxiliary electro-optic phase modulator and a beam combiner, wherein the electro-optic phase to be measured The modulator is placed on one interference arm of the fiber optic interferometer, the acousto-optic frequency shifter and the auxiliary electro-optic phase modulator are placed on the other interference arm; the three devices are respectively loaded with sinusoidal signals of different frequencies; The frequency relationship of the sinusoidal signal eliminates the frequency response of the photodetector, realizes the self-calibration measurement, and improves the accuracy of measuring the modulation coefficient of the electro-optic phase modulator, which has good application value.

The invention relates to the technical field of optical signal regeneration, and discloses a regenerator suitable for wavelength division multiplex-differential phase shift keying (WDM-DPSK) optical signals. The regenerator comprises a first pump laser, a second pump laser, a first polarization controller, a second polarization controller, a first coupler, a second coupler, a first medium, a second medium and a phase regulating module. The second pump laser is connected with an input end of the first polarization controller, and an output end of the first polarization controller is connected with the first coupler. An output end of the first pump laser is connected with an input end of the first coupler. An output end of the first coupler is connected with an input end of the second coupler. The optical signals are incident from an input end of the second polarization controller, an output end of the second polarization controller is connected with the input end of the second coupler, and an output end of the second coupler is connected with the second medium through the first medium. The phase regulating module is connected with two ends of the second medium. By means of the regenerator suitable for the WDM-DPSK optical signals, regeneration of the WDM-DPSK optical signals is achieved.

The invention relates to a vibration monitoring system based on a double fiber grating array, which is characterized in that a narrow linewidth laser, a pulse light modulator, a pulse light amplifierand an optical filter are connected in order, an output terminal of the optical fiber is connected with a first communication terminal of a circulator, a second communication terminal of the circulator is connected with a front first communication terminal of a coupler, a back first communication terminal of the coupler is knotted and out of service, a third communication terminal of the circulator is connected with a first signal input terminal of an embedded signal processor, a front second communication terminal of the coupler is connected with a second signal input terminal of the embeddedsignal processor, a front third communication terminal of the coupler is connected with a third signal input terminal of the embedded signal processor, a back second communication terminal of the coupler is connected with a first optical fiber of the double fiber grating array, and a back third communication terminal of the coupler is connected with a second optical fiber of the double fiber grating array. The vibration monitoring system can restore vibration signals more authentically without increasing the hardware cost.

A calibration method includes forming an external optical path, forming an internal optical path, and conducting a phase comparison between the second part of signals of the internal and external optical paths sequentially received by a second receiving device and the first part of signals of the internal and external optical paths sequentially received by a first receiving device. Two-way phase signals are outputted with part of a base reference being eliminated. Phase comparison is conducted again between the two-way signals with part of the base reference being eliminated, and the final phase signal is outputted with the base reference being eliminated. The distance-measuring device includes a transmitting device, first reflective surface, first and second receiving devices, first and second filters, and a phase detector. This realizes phase compensation and calibration, avoids introducing uncertain phase noise into a circuit due to environmental changes, improves distance-measurement precision, and reduces system costs.

The invention discloses a frequency synthesizer based on a switched capacitor array temperature compensation circuit. The circuit comprises a phase frequency detector, a charge pump, a loop filter, avoltage-controlled oscillator, a driver, a frequency divider and an automatic frequency calibration digital circuit and a temperature compensation circuit, the phase frequency detector identifies thephase difference between the reference clock frequency and the frequency division clock output by the frequency divider; the charge pump converts the phase difference into a corresponding current, thecurrent passes through the loop filter to obtain a corresponding control voltage for controlling the frequency of an output signal of the voltage-controlled oscillator, and the output signal of the voltage-controlled oscillator also passes through the driver to serve as an output signal and is sent to the frequency divider to form a negative feedback loop; the automatic frequency calibration digital circuit is used for selecting an appropriate sub-band for the voltage-controlled oscillator and outputting a sub-band control signal; and the temperature compensation circuit is used for adjustingthe temperature compensation switched capacitor array through the comparator and the digital circuit according to the output signal of the loop filter so as to adjust the output signal of the voltage-controlled oscillator.

Disclosed by the present invention are a laser-based wireless frequency transmission system and a transmission device thereof and a transmission method therefor. The system comprises a transmitting end (10) and at least one receiving end (20). The receiving end (20) comprises a beam returning unit (203) used for reflecting a portion of a received laser signal back to the transmitting end (10). The transmitting end (10) comprises at least one pair of third beam expanders (104) and a phase compensation unit (105). The third beam expander (104) is used for coupling the laser signal reflected back by the receiving end to the phase compensation unit (105). The phase compensation unit (105) is used for comparing in real time the phases of a reference frequency signal and a microwave signal which is modulated in the laser signal reflected back by the receiving end, and adjusting the phase of the laser signal modulated with the reference frequency signal according to a phase error.

The present invention provides a phase calibration method, device, and equipment. The method comprises the steps of: a first light beam emitter generating a first light-wave into a target object, the first light-wave being reflected at the target object and flying back onto a receiver, wherein the first light-wave, as an external beam path signal, is modulated by a first high-frequency oscillation signal; a second light beam emitter emitting a second light-wave into the receiver, wherein the second light-wave, as an internal beam path signal for fundamental phase reference, is modulated by a second high-frequency oscillation signal; and the receiver performing a phase comparison between received first light-wave and sequentially received second light-wave therein and exporting a measurement signal with fundamental reference eliminated. The present method achieves phase compensation and calibration, thereby reducing the influence of environmental elements, increasing measuring precision, and thus reducing system cost.