一种优化模糊度搜索方法的研究

Study on an Optimized GPS Carrier Phase Ambiguity Search Algorithm

对于高精度测量和导航,GPS载波相位整周模糊度的快速求解仍然是一个难点,尤其对于单频接收机。提出一种快速求解整周模糊度的方法,其基本思想采用分步求解,首先应用最小二乘模糊去耦调节法(LAMBDA)搜索出来的模糊度作为初始值,然后应用卫星分组方法降低搜索维数,并应用极大似然准则,构造搜索函数,最后应用最优化原理,搜索出最优的模糊度参数,并从三个方面对其进行检验,即RATIO检验,OVT检验,多项式拟合残差检验。为验证该算法,我们用单频GPS接收机进行了实验,利用本文方法在11 S以内正确确定了模糊度,其基线长误差小于3MM,表明该方法不但可以改进模糊度的搜索速度,而且可以进一步提高其可靠性和成功率。该方法可广泛应用于定向及姿态测量。

GPS carder phase integer ambiguity fast resolution is still the key issue and challenge for high accuracy survey and navigation, especially for single frequency receiver. The algorithm of fast ambiguity resolution is presented in this paper, step resolution is its principle. Firstly, a begging solution is from the LAMBDA search, then decreased dimensions is applied by grouped satellites, and the search function is constructed under the condition of the maximum likelihood law, at last, the optimized ambiguity is searched by the optimization principle, and the ambiguity is tested from the three different aspects, namely ratio test, OVT test and polynomial fit of phase residuals test. We made experiment with single frequency receiver to verify the algorithm, when the experiments data was processed by the method, the ambiguity can be fixed rightly in 11 s, and the error of its baseline is within 3mm. The results of our tests indicate that the above algorithm can improve the ambiguity search speed, and its reliability. The method can be extensively applied to orientation and attitude measure.