A high-precision pseudo-noise ranging system is often required in satellite-formation missions. But in an actual PN ranging system, digital signal processing limits the ranging accuracy, only level up with meter-scale...A high-precision pseudo-noise ranging system is often required in satellite-formation missions. But in an actual PN ranging system, digital signal processing limits the ranging accuracy, only level up with meter-scale. Using non-integer chip to sample time ratio, noncommensurate sampling was seen as an effective solution to cope with the drawback of digital effects. However, researchers only paid attention to selecting specific ratios or giving a simulation model to verify the effectiveness of the noncommensurate ratios. A qualitative analysis model is proposed to characterize the relationship between the range accuracy and the noncommensurate sampling parameters. Moreover, a method is also presented which can be used to choose the noncommensurate ratio and the correlation length to get higher phase delay distinguishability and lower range jitter. The simulation results indicate the correctness of our analyses and the optimal ranging accuracy can be up to centimeter-level with the proposed approach.展开更多
Distortion is a technical indicator in the field of voice signal processing. The design is a portable distortion degree tester, based on Field-Progranmmble Gate Array （FleA, EP2C20） as the cote, using harmonic analy...Distortion is a technical indicator in the field of voice signal processing. The design is a portable distortion degree tester, based on Field-Progranmmble Gate Array （FleA, EP2C20） as the cote, using harmonic analysis method which better solve the distortion problem of acctwacy. It can achieve the signal transformation from the time-domain to the frequency-donkain, and is widely used for signal spectrum analysis. All the componets used in the design are low power, high perf-, low drift and industrial grade compionents. The reference voltage sources of ADC and DAC have identical performance of high stability, high precision. The dtr.k is the precise stable clock with FPGA temperature compensation. This project can get the cost-effective, high-precision, low power and portable design goals.展开更多
Development in industry is asking for improved resolution and higher accuracy in dimensional metrology. In this paper,we proposed a control displacement method based on a polarization ellipsometirc interferometer and ...Development in industry is asking for improved resolution and higher accuracy in dimensional metrology. In this paper,we proposed a control displacement method based on a polarization ellipsometirc interferometer and phase-locked loop technique. The proposed principle was set up. The experimental results of step and step displacements with a step value of 5 nm were presented. We also analyzed the resolution,the potential minimal displacement of the established system. The results show that the position error induced by the ellipticty deviation of the light beam becomes negligible thanks to our signal processing circuit with high-order filter. This method could be useful for many applications in nano dimensional metrology and semiconductor industry.展开更多
基金Project(60904090) supported by the National Natural Science Foundation of China
文摘A high-precision pseudo-noise ranging system is often required in satellite-formation missions. But in an actual PN ranging system, digital signal processing limits the ranging accuracy, only level up with meter-scale. Using non-integer chip to sample time ratio, noncommensurate sampling was seen as an effective solution to cope with the drawback of digital effects. However, researchers only paid attention to selecting specific ratios or giving a simulation model to verify the effectiveness of the noncommensurate ratios. A qualitative analysis model is proposed to characterize the relationship between the range accuracy and the noncommensurate sampling parameters. Moreover, a method is also presented which can be used to choose the noncommensurate ratio and the correlation length to get higher phase delay distinguishability and lower range jitter. The simulation results indicate the correctness of our analyses and the optimal ranging accuracy can be up to centimeter-level with the proposed approach.
文摘Distortion is a technical indicator in the field of voice signal processing. The design is a portable distortion degree tester, based on Field-Progranmmble Gate Array （FleA, EP2C20） as the cote, using harmonic analysis method which better solve the distortion problem of acctwacy. It can achieve the signal transformation from the time-domain to the frequency-donkain, and is widely used for signal spectrum analysis. All the componets used in the design are low power, high perf-, low drift and industrial grade compionents. The reference voltage sources of ADC and DAC have identical performance of high stability, high precision. The dtr.k is the precise stable clock with FPGA temperature compensation. This project can get the cost-effective, high-precision, low power and portable design goals.
基金supported by the National Natural Science Foundation of China (Grant No.50905170)
文摘Development in industry is asking for improved resolution and higher accuracy in dimensional metrology. In this paper,we proposed a control displacement method based on a polarization ellipsometirc interferometer and phase-locked loop technique. The proposed principle was set up. The experimental results of step and step displacements with a step value of 5 nm were presented. We also analyzed the resolution,the potential minimal displacement of the established system. The results show that the position error induced by the ellipticty deviation of the light beam becomes negligible thanks to our signal processing circuit with high-order filter. This method could be useful for many applications in nano dimensional metrology and semiconductor industry.
