Studies On GPS Ambiguity Rapid Resolution And Cycle Slip Detection Technologies Aided By INS

Carrier phase observations and differential resolution method are always used inhigh-precision GPS kinematic positioning, in which the key technologies are to detect cycle slipand fix integer ambiguity correctly. However, GPS satellite signals are easy to be loss of lockwhen kinematic measuring in the areas with many obstacles, such as cities and jungles. As aresult, cycle slip will occur frequently and integer ambiguity fixed formally will be unreliable.Consequently, it is an important issue for high-precision GPS kinematic positioning to recoverinteger ambiguity rapidly and detect cycle slip reliably after GPS is loss of lock. They are alsohot and difficult points of research.Based on GPS precisely dynamic relative positioning technology, two techniques aresystematically analyzed on GPS dynamic positioning aided by INS, that integer ambiguityresolution aided by INS and cycle slip detection aided by INS. Such work contents and researchresults are included as follows:1.The mathematical model of GPS dynamic positioning and INS principle characteristicsare briefly introduced, then error factors to affect the dynamic positioning accuracy and theircorrection methods are analyzed;2.Two key techniques on GPS dynamic positioning are systematically studied, that integerambiguity resolution and cycle slip detection. The results of GPS dynamic positioning resolvedby own program on relative positioning are also given. Such techniques are included in ownprogram that double-difference observation model, satellite location calculated by broadcastephemeris, cycle slip detection by method of ionosphere residual errors, ambiguity float solutionestimated by Kalman Filter, ambiguity integer solution searched by LAMBDA and ambiguityvalidated by method of ratio value test. The resolution results show that: The successful fixedrates arrive at80%or so and99%for L1ambiguity and wide-lane ambiguity respectively in ownrelative positioning program. The RMS of positioning errors for single-frequency L1resolutionis less than two centimeters. As a result, the program has better accuracy and reliability.3.It is studied that GPS integer cycle ambiguity resolution technique aided by INS. Threeaiding methods are given, that direct method, two step method and full combination method. Theequivalence between two step method and full combination method is also deduced. Twoindicators are introduced to evaluated ambiguity search space and resolution accuracytheoretically, that ADOP value and improving percentage of ambiguity resolution accuracy.Based on the two indicators, the changes of ambiguity search space and resolution accuracy areanalyzed through examples under different INS position accuracy and aiding methods. The results show that: the search space will become smaller and the resolution accuracy will improveremarkably when INS position accuracy is better than0.2meters. As INS position accuracy falls,the aiding effects of three methods become less effective correspondingly and the aiding effect ofdirect method fall more quickly.4.The time of fixing ambiguity aided by INS are given under different time of losing lockand three aiding methods. The results show that: ambiguity resolution aided by INS can shortenambiguity fixed time reduced and recover integer ambiguity rapidly in the case of GPSshort-term loss of lock, such as loss of lock time is less than30seconds.5.It is studied that GPS cycle slip detection technique aided by INS. Such methods are usedthat cycle slip detectable variable constructed based on Kalman Filter new interest test theory,cycle slip test by method of chi-square test and cycle slip identification and positioning usingminimum detectable bias(MDB). The characteristic of cycle slip detectable variable and MDBvalue are analyzed through examples, while simulated cycle slips are detected using suchtechnique. The results show that such technique can not only detect single cycle slip, but alsodetect multiple cycle slips simultaneously. At the same time, such small cycle slip as one cyclecan be detected correctly.