Aiming at the potential presence of mixing automatic identification system(AIS) signals,a new demodulation scheme was proposed for separating other interfering signals in satellite systems.The combined iterative cross...Aiming at the potential presence of mixing automatic identification system(AIS) signals,a new demodulation scheme was proposed for separating other interfering signals in satellite systems.The combined iterative cross-correlation demodulation scheme,referred to as CICCD,yielded a set of single short signals based on the prior information of AIS,after the frequency,code rate and modulation index were estimated.It demodulates the corresponding short codes according to the maximum peak of cross-correlation,which is simple and easy to implement.Numerical simulations show that the bit error rate of proposed algorithm improves by about 40% compared with existing ones,and about 3 dB beyond the standard AIS receiver.In addition,the proposed demodulation scheme shows the satisfying performance and engineering value in mixing AIS environment and can also perform well in low signal-to-noise conditions.展开更多
A novel scheme of differential polarization demodulation is presented and demonstrated based on a polarized asym- metrical Mach-Zehnder interferometer configuration with polarization control. To enhance the stability ...A novel scheme of differential polarization demodulation is presented and demonstrated based on a polarized asym- metrical Mach-Zehnder interferometer configuration with polarization control. To enhance the stability of the demodulator, a phase-lock device is designed, and it is composed of a symmetric 3 × 3 coupler and a feedback circuit. For further estab- lishing a differential polarization-shift keying （DPolSK） transmission system, we successfully carry out the demodulation experiments on 10-Gb/s DPolSK optical signals for the first time. Due to the all-optical structure with phase-lock, our scheme is available to realize the DPolSK optical communication in practical optical fiber systems.展开更多
High frequency pulsating voltage injection method is a good candidate for detecting the initial rotor position of permanent magnet synchronous motor.However,traditional methods require a large number of filters,which ...High frequency pulsating voltage injection method is a good candidate for detecting the initial rotor position of permanent magnet synchronous motor.However,traditional methods require a large number of filters,which leads to the deterioration of system stability and dynamic performance.In order to solve these problems,a new signal demodulation method is proposed in this paper.The proposed new method can directly obtain the amplitude of high-frequency current,thus eliminating the use of filters,improving system stability and dynamic performance and saving the work of adjusting filter parameters.In addition,a new magnetic polarity detection method is proposed,which is robust to current measurement noise.Finally,experiments verify the effectiveness of the method.展开更多
In this work,we analyze and demonstrate a novel photonic-assisted broadband and high-resolution radio frequency(RF) channelization scheme based on dual coherent optical frequency combs(OFCs),regular optical de-muxes,a...In this work,we analyze and demonstrate a novel photonic-assisted broadband and high-resolution radio frequency(RF) channelization scheme based on dual coherent optical frequency combs(OFCs),regular optical de-muxes,and polarization I/Q demodulators in theory and experiment.The use of two coherent combs avoids precise optical alignment,and a numerical filter in digital signal processor(DSP) enables an ideal rectangular frequency response in each channel without any ultra-narrow optical filters.Besides,due to the use of polarization I/Q demodulation,ambiguous frequency estimate in direct detection can be avoided and the amplitude,phase mismatch in traditional I/Q demodulation can be mitigated.In experiment,we use two coherent OFCs with the free spectrum range(FSR) of about 40 GHz to demonstrate the channelization scheme with seven channels,500 MHz channel spacing and frequency coverage from 3.75 GHz to 7.25 GHz.The input RF tones are accurately down-converted to an intermediate frequency(IF) with a maximum frequency error of 110 kHz.Meanwhile,crosstalk and spurious free dynamic range(SFDR) of the scheme are also discussed.展开更多
A new algorithm using polar coordinate system similarity （PCSS） for tracking particle in particle tracking velocimetry （PTV） is proposed. The essence of the algorithm is to consider simultaneously the changes of t...A new algorithm using polar coordinate system similarity （PCSS） for tracking particle in particle tracking velocimetry （PTV） is proposed. The essence of the algorithm is to consider simultaneously the changes of the distance and angle of surrounding particles relative to the object particle. Monte Carlo simulations of a solid body rotational flow and a parallel shearing flow are used to investigate flows measurable by PCSS and the influences of experimental parameters on the implementation of the new algorithm. The results indicate that the PCSS algorithm can be applied to flows subjected to strong rotation and is not sensitive to experimental parameters in comparison with the conventional binary image cross-correlation （BICC） algorithm. Finally, PCSS is applied to images of a real experiment.展开更多
A multi-channel synchronous demodulation system of a polarized low-coherence interferometer(PLCI) based on a matrix charge-coupled-device(CCD) is proposed and demonstrated. By using special designs, the system allows ...A multi-channel synchronous demodulation system of a polarized low-coherence interferometer(PLCI) based on a matrix charge-coupled-device(CCD) is proposed and demonstrated. By using special designs, the system allows the signals from different channels to be received and demodulated synchronously. Multichannel air pressure experiments were implemented to verify the effectiveness of the proposed system. The experiment results showed that the Fabry–Perot(F–P) sensors could be demodulated synchronously with a high tolerance for light sources and sensors, which indicated that any sensor and light source that can be demodulated by PLCI were allowed to be employed, leading to a wide application in the field of multichannel synchronous measurement.展开更多
基金Project(9140C860304) supported by the National Defense Key Laboratory Foundation of China
文摘Aiming at the potential presence of mixing automatic identification system(AIS) signals,a new demodulation scheme was proposed for separating other interfering signals in satellite systems.The combined iterative cross-correlation demodulation scheme,referred to as CICCD,yielded a set of single short signals based on the prior information of AIS,after the frequency,code rate and modulation index were estimated.It demodulates the corresponding short codes according to the maximum peak of cross-correlation,which is simple and easy to implement.Numerical simulations show that the bit error rate of proposed algorithm improves by about 40% compared with existing ones,and about 3 dB beyond the standard AIS receiver.In addition,the proposed demodulation scheme shows the satisfying performance and engineering value in mixing AIS environment and can also perform well in low signal-to-noise conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.11274037 and 61275075)the Program for New Century Excellent Talents in University,Ministry of Education of China(Grant No.NCET-12-0765)the Foundation for the Author of National Excellent Doctoral Dissertation,China(Grant No.201236)
文摘A novel scheme of differential polarization demodulation is presented and demonstrated based on a polarized asym- metrical Mach-Zehnder interferometer configuration with polarization control. To enhance the stability of the demodulator, a phase-lock device is designed, and it is composed of a symmetric 3 × 3 coupler and a feedback circuit. For further estab- lishing a differential polarization-shift keying （DPolSK） transmission system, we successfully carry out the demodulation experiments on 10-Gb/s DPolSK optical signals for the first time. Due to the all-optical structure with phase-lock, our scheme is available to realize the DPolSK optical communication in practical optical fiber systems.
基金supported by the National Natural Science Foundation of China under Grant 51991384Anhui Provincial Major Science and Technology Project under Grant 202203c08020010。
文摘High frequency pulsating voltage injection method is a good candidate for detecting the initial rotor position of permanent magnet synchronous motor.However,traditional methods require a large number of filters,which leads to the deterioration of system stability and dynamic performance.In order to solve these problems,a new signal demodulation method is proposed in this paper.The proposed new method can directly obtain the amplitude of high-frequency current,thus eliminating the use of filters,improving system stability and dynamic performance and saving the work of adjusting filter parameters.In addition,a new magnetic polarity detection method is proposed,which is robust to current measurement noise.Finally,experiments verify the effectiveness of the method.
基金supported in part by the Major State Basic Research Development Program of China ("973" Program) (Grant No. 2012CB315705)National Natural Science Foundation of China (Grant Nos. 61107058, 61120106001)+1 种基金the National High Technology Research and Development Program of China ("863" Program) (Grant No. 2011AA010306)the Fundamental Research Funds for the Central Universities of China
文摘In this work,we analyze and demonstrate a novel photonic-assisted broadband and high-resolution radio frequency(RF) channelization scheme based on dual coherent optical frequency combs(OFCs),regular optical de-muxes,and polarization I/Q demodulators in theory and experiment.The use of two coherent combs avoids precise optical alignment,and a numerical filter in digital signal processor(DSP) enables an ideal rectangular frequency response in each channel without any ultra-narrow optical filters.Besides,due to the use of polarization I/Q demodulation,ambiguous frequency estimate in direct detection can be avoided and the amplitude,phase mismatch in traditional I/Q demodulation can be mitigated.In experiment,we use two coherent OFCs with the free spectrum range(FSR) of about 40 GHz to demonstrate the channelization scheme with seven channels,500 MHz channel spacing and frequency coverage from 3.75 GHz to 7.25 GHz.The input RF tones are accurately down-converted to an intermediate frequency(IF) with a maximum frequency error of 110 kHz.Meanwhile,crosstalk and spurious free dynamic range(SFDR) of the scheme are also discussed.
基金supported by the National Natural Science Foundation of China(50206019)
文摘A new algorithm using polar coordinate system similarity （PCSS） for tracking particle in particle tracking velocimetry （PTV） is proposed. The essence of the algorithm is to consider simultaneously the changes of the distance and angle of surrounding particles relative to the object particle. Monte Carlo simulations of a solid body rotational flow and a parallel shearing flow are used to investigate flows measurable by PCSS and the influences of experimental parameters on the implementation of the new algorithm. The results indicate that the PCSS algorithm can be applied to flows subjected to strong rotation and is not sensitive to experimental parameters in comparison with the conventional binary image cross-correlation （BICC） algorithm. Finally, PCSS is applied to images of a real experiment.
基金supported by the National Natural Science Foundation of China(Nos.61735011,61675152 and 61505139)National Instrumentation Program of China(No.2013YQ030915)China Postdoctoral Science Foundation(No.2016M590200)
文摘A multi-channel synchronous demodulation system of a polarized low-coherence interferometer(PLCI) based on a matrix charge-coupled-device(CCD) is proposed and demonstrated. By using special designs, the system allows the signals from different channels to be received and demodulated synchronously. Multichannel air pressure experiments were implemented to verify the effectiveness of the proposed system. The experiment results showed that the Fabry–Perot(F–P) sensors could be demodulated synchronously with a high tolerance for light sources and sensors, which indicated that any sensor and light source that can be demodulated by PLCI were allowed to be employed, leading to a wide application in the field of multichannel synchronous measurement.
