GPS positioning precision is affected by various error sources, and traditional combinations of GPS carrier phase observations have their own limitations such as the wide-lane, the narrow-lane and the ionospheric-free...GPS positioning precision is affected by various error sources, and traditional combinations of GPS carrier phase observations have their own limitations such as the wide-lane, the narrow-lane and the ionospheric-free combinations. To obtain the optimal positioning precision, a new linear combination method is addressed through the variance-covariance （VCV） of the GPS multi-frequency carrier phase combination equations, and the impact of the positioning precision is analyzed with the changing of the observation errors deduced by the law of error propagation. For the high precision positioning with only one carrier phase combination, the optimal combination method is deduced and further validated by an example of a baseline resolution with 60 km length. The result indicates that this method is the simplest, and the positioning precision is the best. Therefore, it is useful for long baseline quick positioning for different precision requirements in various distances.展开更多
In the traditional dual-frequency radar ranging system,there is a contradiction between ranging precision and ranging distance.So a tri-frequency ranging method is proposed.The principle of the tri-frequency ranging i...In the traditional dual-frequency radar ranging system,there is a contradiction between ranging precision and ranging distance.So a tri-frequency ranging method is proposed.The principle of the tri-frequency ranging is that the distance can be achieved by transmitting the three frequencies and then measuring the three phase difference and calculating the number of wavelength.What's more,range ambiguity will not occur within a certain distance.The experimental results show that,if the waveband is 0.47 ~0.57 m,the measurement of unambiguous distance of 25 ~500m can be realized.If the wavelength tolerance error is less than ± 10^(-7) and the phase error is less than ± 10^(-3),the precision of the distance ranging can reach 10^(-6).展开更多
According to the time&space conversion relations and different frequency phase detection principle,an ultra-high precision time&frequency measurement method is proposed in this paper.The higher accuracy and st...According to the time&space conversion relations and different frequency phase detection principle,an ultra-high precision time&frequency measurement method is proposed in this paper.The higher accuracy and stability of the speed of light and electromagnetic signals during the transmission in space or a specific medium enable the measurement of short time interval which uses the coincidence detection of signal’s transmission delay in length.The measurement precision better than 10 picoseconds can be easily obtained.The method develops the length vernier utilizing the stability of signal’s transmission delay,minimizes the fuzzy region of phase coincidence between the standard frequency signal and the measured signal,approaches the best phase coincidences and therefore improves the measurement precision which is higher than the precision provided by the traditional methods based on frequency processing.Besides,the method costs less than the traditional methods and can also solve the problem of the measurement of super-high frequency.Experimental results show the method can improve the measurement precision to 10 12/s in the time&frequency domain.展开更多
Optical-phase-retardation elements are widely used in many fields.Accurate measurement of their phase retardation is crucial to the practical effect of the element's processing and application.The development and ...Optical-phase-retardation elements are widely used in many fields.Accurate measurement of their phase retardation is crucial to the practical effect of the element's processing and application.The development and present situation of the methods for optical phase retardation measurement are reviewed,with the wave plate,the most typical phase-retardation element,as an example.The latest research progress in this field is introduced;the principles and characteristics of individual measurement method are summarized and discussed.Three new methods based on laser frequency splitting or laser feedback are presented in detail,in which the laser is not only regarded as a light source but also plays a role of sensor.Moreover,no standard wave plates are needed and arbitrary phase retardation can be measured.Traceability,high precision and high repeatability are achieved as well.展开更多
基金Supported by the Key Laboratory of Geological Hazards on Three Gorges Reservoir Area,Ministry of Education, China(No.2006KDZ05).
文摘GPS positioning precision is affected by various error sources, and traditional combinations of GPS carrier phase observations have their own limitations such as the wide-lane, the narrow-lane and the ionospheric-free combinations. To obtain the optimal positioning precision, a new linear combination method is addressed through the variance-covariance （VCV） of the GPS multi-frequency carrier phase combination equations, and the impact of the positioning precision is analyzed with the changing of the observation errors deduced by the law of error propagation. For the high precision positioning with only one carrier phase combination, the optimal combination method is deduced and further validated by an example of a baseline resolution with 60 km length. The result indicates that this method is the simplest, and the positioning precision is the best. Therefore, it is useful for long baseline quick positioning for different precision requirements in various distances.
基金Supported by the National Natural Science Foundation of China(No.61107052)the National Natural Science Foundation of Tianjing(No.11JCYBJC00100)
文摘In the traditional dual-frequency radar ranging system,there is a contradiction between ranging precision and ranging distance.So a tri-frequency ranging method is proposed.The principle of the tri-frequency ranging is that the distance can be achieved by transmitting the three frequencies and then measuring the three phase difference and calculating the number of wavelength.What's more,range ambiguity will not occur within a certain distance.The experimental results show that,if the waveband is 0.47 ~0.57 m,the measurement of unambiguous distance of 25 ~500m can be realized.If the wavelength tolerance error is less than ± 10^(-7) and the phase error is less than ± 10^(-3),the precision of the distance ranging can reach 10^(-6).
基金supported by the National Natural Science Foundation of China (Grant No. U1304618)the Open Fund of Key Laboratory of Precision Navigation and Timing Technology of Chinese Academy of Sciences(Grant No. 2012PNTT01)+5 种基金the Postdoctoral Grant of China (Grant Nos. 2011M501446, 2012T50798)the Basic and Advanced Technology Research Foundation of Henan Province under Grant (Grant No. 122300410169)The Key Science and Technology Foundation of Henan Province under Grant (Grant No. 132102210180)the Doctor Fund of Zhengzhou University of Light Industry under (Grant No. 2011BSJJ031)the Scientific Research Fund of Zhengzhou University of Light Industry under (Grant No. 2012XJJ009)the Fundamental Research Funds for the Central Universities(Grant No. K5051204003)
文摘According to the time&space conversion relations and different frequency phase detection principle,an ultra-high precision time&frequency measurement method is proposed in this paper.The higher accuracy and stability of the speed of light and electromagnetic signals during the transmission in space or a specific medium enable the measurement of short time interval which uses the coincidence detection of signal’s transmission delay in length.The measurement precision better than 10 picoseconds can be easily obtained.The method develops the length vernier utilizing the stability of signal’s transmission delay,minimizes the fuzzy region of phase coincidence between the standard frequency signal and the measured signal,approaches the best phase coincidences and therefore improves the measurement precision which is higher than the precision provided by the traditional methods based on frequency processing.Besides,the method costs less than the traditional methods and can also solve the problem of the measurement of super-high frequency.Experimental results show the method can improve the measurement precision to 10 12/s in the time&frequency domain.
基金supported by the Key Program of National Natural Science Foundation of China(Grant No.61036016)
文摘Optical-phase-retardation elements are widely used in many fields.Accurate measurement of their phase retardation is crucial to the practical effect of the element's processing and application.The development and present situation of the methods for optical phase retardation measurement are reviewed,with the wave plate,the most typical phase-retardation element,as an example.The latest research progress in this field is introduced;the principles and characteristics of individual measurement method are summarized and discussed.Three new methods based on laser frequency splitting or laser feedback are presented in detail,in which the laser is not only regarded as a light source but also plays a role of sensor.Moreover,no standard wave plates are needed and arbitrary phase retardation can be measured.Traceability,high precision and high repeatability are achieved as well.
