GPS／GLONASS组合定位中模糊度的处理

在对GPS／GLONASS组合定位的周跳探测和修复方法进行深入研究的基础上，论述了适合于两种数据联合解算的GPS／GLONASS模糊度迭代处理方法及相应的基于FARA方法的整周模糊度固定方法。在现有BERNESE Ver4.0GSP数据处理软件的基础上，增加及改进了其中的若干模块，从而研制出组合定位系统高精度数据处理软件，并进行了试验计算。结果表明，所开发的组合定位系统数据处理软件内、外符合精度均达到mm级，证明了这种高精度相对定位理论、方法、软件的正确性和可行性。

Ambiguity ProcessingApproach in Combined GPS/GLONASS Positioning

The construction and status of GPS and GLONASS are introduced precisely, then the iterative detecting and repairing method of cycle slips based on triple_difference residue on combined GPS/GLONASS positioning are discussed systematically. The basic principle is taking iterations of triple_difference observations, and repairing some cycle slips in every iteration until all cycle slips are repaired or introducing new ambiguities while the cycle slips can not be repaired. Then an iterative ambiguity resolution approach suitable for combined data processing of GPS/GLONASS observations and the corresponding ambiguity fixing strategy based on FARA (fast ambiguity resolution algorithm) method are discussed. Because of the FDMA (frequency difference multiple address) technology used by GLONASS, the frequency and corresponding wavelength are not equal among different GLONASS satellites,and when making double_difference between GLONASS or GPS/GLONASS satellite pairs, the ambiguities will not maintain integrity_character as GPS satellite pairs. So the ambiguity can not be fixed to integer as common GPS only positioning. A transformation of the double_difference observation is taken, then every double_difference equation contains an integrity_characterized double_difference ambiguity and a single_difference ambiguity related part of the reference satellite. Then the double_difference and single_difference ambiguities can be fixed using the SEARCH strategy based on statistics. For dual_frequency data, geometry_free L 4 observations can be made to fix ambiguities. Based on the forenamed theory and BERNESE Ver 4.0 GPS only processing software, several modules are added and improved. Thus, high precision data processing software on combined GPS/GLONASS relative positioning(we call it improved BERNESE) is accomplished, then some experiments are taken and the observations are processed to verify the precision of the data processing software. Precise GPS/GLONASS ephemeris of International GLONASS experiment, sampling rate of 15 seconds,cutting off angle of 15 degree, troposphere model of Saastamoinen and standard meteorological parameters are adopted. The single_frequency GPS/GLONASS data collected by GG24 receivers are divided into GPS only and GPS/GLONASS combined.The GPS only data are processed using BERNESE Ver 4.0 GPS only processing software, and the improved BERNESE software processes GPS/GLONASS observations. The data processing results indicate that the result precision of several hours' single_frequency data is bellow several millimeters. In order to check the exterior precision of the enhanced BERNESE software thoroughly, another experiment is taken in November 1999 with JAVAD GPS/GLONASS dual_frequency receivers. 40 hours' data are cut into 20 segments of 2 hours' data, then the same processing strategy is used, and the results of improved BERNESE software are compared with the results of Pinnacle software developed by JAVAD company. The comparison shows that the result precision of 2 hours' dual_frequency observations is only a few millimeters. It is obvious that the result precision of dual_frequency observations is higher than that of single_frequency observations. The results of these experiments prove the correctness of the iterative detecting and repairing method of cycle slips based on triple_difference residues and the iterative ambiguity processing approach suitable for combined positioning. The precision of the software is at the order of millimeter on short baselines, which prove the correctness and feasibility of the high precision relative positioning theory, method and the data processing software itself, and open a new approach of broad application in the future.