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

The invention is applicable to the field of phase type photoelectric distance measurement and provides a calibration method based on phase measurement of a double-wavelength laser tube and a distance measurement device of the double-wavelength laser tube. The method comprises the following steps of: 1, forming an external light path; 2, forming an internal light path; and 3, sequentially switching a first light wave and a second light wave of light wave transmitting devices (1 and 2) during operation of the steps 1 and 2 to compare phases of the sequentially-received light waves of the internal and external light paths through a receiving device (7), and outputting a phase signal for eliminating a base reference. By the method, aims of phase compensation and calibration are fulfilled, uncertain phase noise which is introduced into a circuit due to environmental change is eliminated, the distance measurement accuracy of laser is improved, the influence of environmental factors on a distance measurement error is reduced, the cost of a system is reduced, and application of a phase type photoelectric distance measurement system in various industries is enhanced.

A multi-mode PLL frequency synthesizer of a wireless multi-mode transceiver is provided which includes a reference frequency source providing an oscillator signal with a constant reference frequency, a first frequency synthesizer subunit for converting the signal into carrier signals with frequencies in the range of a first frequency band, a second frequency synthesizer subunit for transforming the oscillator signal into carrier signals having frequencies in the range of a second frequency band, and a third frequency synthesizer subunit for converting the oscillator signal into an auxiliary signal with a fixed frequency. The auxiliary signal is used together with the carrier signals of the second frequency band to generate carrier signals with frequencies in the range of a third and fourth frequency band. A frequency divider derives a signal in the range of a fifth frequency band from further intermediate frequency signals supplied by the third frequency synthesizer subunit by dividing the frequency of the auxiliary signal by an integer value.

A voltage-controlled oscillator (VCO) for a multi-band receiver, and a radio-frequency (RF) communication apparatus having the same. The VCO includes at least two fine tune branches, that is, a main fine tune branch and an auxiliary fine tune branch. The main fine tune branch includes at least one variable capacitor whose capacitance varies according to a tuning voltage. The auxiliary fine tune branch includes at least one varactor that operates either as a variable capacitor whose capacitance varies according to the tuning voltage or a fixed capacitor regardless of the tuning voltage, based on an operating frequency band. Accordingly, it is possible to prevent phase noise from increasing by varying the gain of the VCO according to the frequency band of an oscillation signal from the VCO.

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 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 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 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.

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.

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.