摘要
ＮＮＳＳ和ＧＰＳ是当今世界的两大卫星导航系统，为掌握此二系统的发展趋向，我们在大连水产学院导航实验室对它们进行了一系列的跟踪研究。观测和数据处理的结果表明：（１）ＮＮＳＳ的卫星总数从１９９２年３～４月的７颗降为１９９４年４月的６颗，更新定位的平均间隔时间则从原来的５１．０６ｍｉｎ增为６０．６８ｍｉｎ。（２）ＧＰＳ的卫星总数从１９９１年５月的１５颗增至１９９４年４月的１９颗，每天可进行二维和三维定位的时间则分别从占全天２４ｈ的８２．８％～９２．３％和５５．０％～７４．３％变为可全天２４ｈ连续进行二维和三维定位。（３）由于美国政府已对ＧＰＳ工作卫星实施ＳＡ，ＧＰＳ的水平定点定位精度已从１９９１年５月的１４．７２ｍ（９５％）降为１９９４年４月的７３．８７ｍ（９５％）．（４）ＮＮＳＳ无疑将最终被ＧＰＳ所淘汰，但被淘汰的具体时间有待进一步观测。
NNSS and GPS are two main stellite navigation systems in the world. A study tracing the development trend of the two systems has been carried out at the navigation laboratory of Dalian Fisheries College,and the observation and da-ta processing results show were shown as follors:1.The total number of NNSS satellites has been reduced from 7(March-April,1992)to 6(April,1994),and the mean update interval of positioning has been increasedfrom 51.06 to 60.68 min.2.The total number of GPS satellites has been increased from 15(May,1991)to 19(April, 1994).At the first observation,the 2D and 3 D daily posi-tioning time covers 82.8%～92.3%and 55.0%～74.3%for the 24 hours re-spectively. At the second observation,GPS has been capable of full-time 2D and 3D continuous positioning.3.Since the US government has carried out SA on the GPS working satel-lites,the C/A code horizontal positioning accuracy at a fixed point has been re-duced from 14.72 m(95%, May,1991)to 73.87 m(95%, April, 1994). 4.There is no doubt that NNSS will finally be phased out by GPS,and the exact date of phase-out needs further observation.
出处
《大连水产学院学报》
CSCD
1995年第3期12-19,共8页
Journal of Dalian Fisheries University
