单双频混合GNSS变形监测系统中单频点电离层误差改正

采用单双频GNSS混合模式进行变形监测的关键是利用双频点数据建立区域电离层误差改正模型，并对单频点的电离层延迟误差进行改正，从而使单频点监测精度也能满足要求。利用广州南沙单双频地面沉降监测网数据对LCM、DIM、LIM、LSM四种区域电离层误差改正模型及其建立方案进行实例，结果表明，4种电离层误差改正模型均能显著改善单频点的监测精度，其中LCM与LIM较优，且利用单频点周围近距离的3个双频点构建区域电离层模型的处理策略最佳。

Ionosphere Delay Correction for Single Frequency Points in a GNSS Deformation Monitoring System with Mixed Single and Dual Frequency Mode

To reduce hardware costs, mixed single and dual frequency GNSS mode is used in deformation monitoring. The key technological challenge of this mode concerns how to use the data of dual frequency points to build a precise regional ionosphere error correction model for the single frequency point, so that the accuracy of single frequency points can meet the demand. To meet this challenge, the data of land subsidence monitoring network in Nansha, Guangzhou is used to analyze 4 different ionosphere correction models (LCM, DIM, LIM and LSM) and processing strategies. The result shows that all of the 4 models can improve the monitoring precision of single frequency point, and that LCM and LIM perform better than DIM and LSM. It also indicates the strategy using three dual frequency points nearest to the single frequency point is best for constructing the ionosphere correction model.