Expansion Of Gps Satellite Status Of The Overall Measurement

In the case of the formation flying constellation,the paper discusses some problems about the determination of states as a whole,which include position,attitude and time,by using pseudo-ranging and carrier phase of onboard GPS or pseudolites.The researches are as follows.I. First step is absolute positioning and timing at single epoch by using successive pseudo-ranging measurements. Second step is relative positioning and timing by using successive measurements of continuous but biased carrier phase. Last step is overall adjustment by using multi-epoch absolute and relative results of positioning and timing,in order to improve precision of positioning and timing.II. Some problems about attitude determination and integrity ambiguity resolving by using GPS carrier phase are discussed.III. Because the number of GPS satellites in sight is little and integrity ambiguity of carrier phase difference inter-satellite is difficult to be determined fast when using GPS to resolve states of formation flying constellation as a whole,the paper uses onboard pseudolites to determine relative states of inter-satellite.The paper consists of four chapters. In the first chapter,background,significance,method and contents of the researches are introduced. In the second chapter,it is discussed that some problems about positioning and timing by using GPS. The third chapter involves some problems on attitude determination and integrity ambiguity resolving. Using three formation flying satellites for an earth observation as an example,the forth chapter contains some problems about determination of inter-satellite position,attitude and time,by using high precise pseudo-ranging observation onboard pseudolites. The problems are the selecting of coordinate system and independent state parameters,the setting of observation equations,and the conversion of constellation's states. In the second,third and forth chapters,some numerical simulations and analyses are given. Lastly,a summary and expectation for paper work are listed.