| Time is the highest accuracy of measurement of physical quantities， andis widely applied in measuring, testing, navigation, communications, defense, military and otherfields. But limited to existing timing technology and cost budget requirements (Telephone andnetwork time service is difficult to realize the timing precision of nanosecond, and high precisionsatellite two-way remote time comparison cost is too high), although the difference between ourstandard time and coordinated universal time (UTC) in30nanosecond (ns), it is too costly fordomestic users to get nanosecond time broadcasting accuracy. So it is necessary that the highprecision of remote calibration system that can be tracing to the source of the national/internationalstandard time by local users. Based on the principle of common view of navigation satellite,researched the methods to realize the data processing center of remote time calibration system, andanalyzed the performance of the system by the experiments of zero-base line and long baselinetime calibration. The main research contents are as follows:1) Based on the existing remote time calibration method, analyzed the advantages anddisadvantages of each method, it is proposed that the remote time calibration methodof based on the navigation satellite continuous common view be different from thetraditional timing method of satellite common view, it made the moreflexible uninterrupted schedules of common view, to measured more observed datain same observation period of time, and realized the continuous monitoring andimproving the accuracy of the users of the system time performance analysis resultsby satellite observations and data processing parallelization. It provides users withtraceability to national standards of reliable time calibration data.2) The methods of corrected system error in continuous common view time calibration werestudied. Improve the accuracy of remote calibration time. Experiments shows that usingthe mean value as the system sent revised continuous measurement data can effectivelyeliminate the system error.3) Studies the method of gross error elimination that suitable for this system, ensure thereliability of the measurement results. Our system in a single calibration, the total numberof common view satellites is less than20, be used in gross error elimination of Wright’scriterion is not suitable for this system. Based on the characteristic of this system,proposed using a single calibration data in the value of3times as the threshold identifying, and experiment show that through this method can effectively eliminate the single grosserror calibration data.4) Based on the system characteristics of user data, this paper puts forward the solutionof conflicts caused by multiple tasks concurrently shared resource in multi-user system.There are the characteristics of user data in system is similar structure and highconcurrency. In the process of design, in addition to the commonly used multithreadingtechnology, through redundant high shared resource utilization rate for the user to set uptheir own channels data acquisition, data storage and data processing, greatly improve theefficiency of the response of the system.5) By study of interactive database application design method, and using MySQL databasemanagement system and the United States NI Lab Windows virtual instrument platform,program an software to realize the data processing center management system, and datastorage software analysis system. Using a database stored procedure package morecomplex data processing algorithms, to improve the stability of the system at the sametime, meet the needs of the user’s secondary development.6) Design the zero-base line, long baseline time calibration experiments, the system functionwas tested, and analyses the remote time calibration measurement performance of thesystem by measurement uncertainty evaluation based on system theory.The data processing center done in this paper have put into operation as the components ofremote time calibration system. By zero-base line a total of5days common view calibration and5days space-based line length is1800km long baseline calibration test, the system of domesticusers of the baseline length of1800kilometers of the local time calibration uncertainty of A classis3.2ns, uncertainty of B class is5.5ns, when extended factor k=2, synthetic uncertainty is betterthan that of13ns. |
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