Triple-frequency GPS precise point positioning with rapid ambiguity resolution
Triple-frequency GPS precise point positioning with rapid ambiguity resolution
复制标题
DOI：
10.1007/s00190-013-0619-2
复制
发表时间：
2013-05-01
影响因子：
4.4
通讯作者：
Bock, Yehuda
中科院分区：
文献类型：
--
作者：
Geng, Jianghui;Bock, Yehuda
目前，实时GPS精密单点定位(PPP)需要经过几十分钟的初始观测周期，才能实现可靠的模糊度解算。在这项研究中，我们提出了一种方法，其中利用输入的三频GPS信号来实现实时PPP快速收敛到模糊度固定的解。具体地说，通过在L2和L5上观察到的墨尔本-乌布纳组合，可以首先几乎瞬时地实现超宽车道模糊度的解决。然后将得到的无模糊超宽道载波相位与L1和L2上的宽道载波相结合，形成波长约为3.4m的无电离层观测值，虽然该观测值的噪声约为原始载波相噪声的100倍，但它的宽道模糊度仍然可以非常有效地求解，并且模糊固定的观测值在加速后续窄道模糊度解算方面比伪距要好得多。为了验证该方法的有效性，我们使用先进的硬件模拟器来产生三倍频信号，并使用高级接收器来采集1赫兹的数据。当L1、L2和L5上的载波相位精度分别为1.5mM、6.3mM和1.5mM时，在20 S以内，宽道模糊度解算的正确率仍可达到99%以上，从而使得窄道模糊度解算的正确率在65 S以内达到99%，而双频PPP在150 S以内的正确率仅为。此外，我们还模拟了一个受多径污染的数据集，并对所有卫星每隔120个S引入新的模糊度。我们发现，当多径效应较强时，三频PPP在所有历元中有78%获得了模糊度固定的解，而双频PPP几乎没有模糊解。因此，我们证明，三频PPP有可能在几分钟内实现模糊度固定的解，如果原始载波相位精度约为1 mm，则甚至更短。在这两种情况下，我们得出结论：三频PPP的歧义消解效率远高于双频PPP。
At present, reliable ambiguity resolution in real-time GPS precise point positioning (PPP) can only be achieved after an initial observation period of a few tens of minutes. In this study, we propose a method where the incoming triple-frequency GPS signals are exploited to enable rapid convergences to ambiguity-fixed solutions in real-time PPP. Specifically, extra-wide-lane ambiguity resolution can be first achieved almost instantaneously with the Melbourne-Wubbena combination observable on L2 and L5. Then the resultant unambiguous extra-wide-lane carrier-phase is combined with the wide-lane carrier-phase on L1 and L2 to form an ionosphere-free observable with a wavelength of about 3.4 m. Although the noise of this observable is around 100 times the raw carrier-phase noise, its wide-lane ambiguity can still be resolved very efficiently, and the resultant ambiguity-fixed observable can assist much better than pseudorange in speeding up succeeding narrow-lane ambiguity resolution. To validate this method, we use an advanced hardware simulator to generate triple-frequency signals and a high-grade receiver to collect 1-Hz data. When the carrier-phase precisions on L1, L2 and L5 are as poor as 1.5, 6.3 and 1.5 mm, respectively, wide-lane ambiguity resolution can still reach a correctness rate of over 99 % within 20 s. As a result, the correctness rate of narrow-lane ambiguity resolution achieves 99 % within 65 s, in contrast to only 64 % within 150 s in dual-frequency PPP. In addition, we also simulate a multipath-contaminated data set and introduce new ambiguities for all satellites every 120 s. We find that when multipath effects are strong, ambiguity-fixed solutions are achieved at 78 % of all epochs in triple-frequency PPP whilst almost no ambiguities are resolved in dual-frequency PPP. Therefore, we demonstrate that triple-frequency PPP has the potential to achieve ambiguity-fixed solutions within a few minutes, or even shorter if raw carrier-phase precisions are around 1 mm. In either case, we conclude that the efficiency of ambiguity resolution in triple-frequency PPP is much higher than that in dual-frequency PPP.