资源环境科技发展态势分析平台

Global navigation satellite system (GNSS) displacements at near-source stations can be biased in both amplitude and phase due to fierce earthquake strike. We propose to inject inertial measurement unit (IMU)-recorded ground motions into GNSS receivers to compensate their phase-lock loops (PLLs) for seismic motion stress, aiming at keeping steady carrier-phase tracking. We use a shake table to replay an acceleration record (0.5-2.0 g) from the 2008 Mw7.9 Wenchuan earthquake to test this IMU-augmented PLL: It achieves a 1.9-mm amplitude error (RMS) and an 8.0-ms phase lag against the shake table's recordings, while the conventional PLL languishes to 6.0 mm and 56.5 ms, respectively. Moreover, the IMU-augmented PLL enables a six-degree-of-freedom integration among the GNSS and IMU data, where the displacement amplitude error and phase lag decline further to 0.9 mm and 3.5 ms, respectively. We believe that the IMU-augmented GNSS receivers are ideal strong-motion seismograph to capture trustworthy broadband displacements in the near fields.