差分导航定位系统及其在海洋工程地震勘察中的应用

The Application of the Differential GPS System in Seismic Survey for Offshore Projects

差分导航定位是海洋工程地震勘探中不可或缺的技术手段。差分导航定位分为局域差分和广域差分,文中分别介绍了隶属于局域差分的信标差分(RBN DGPS)系统和隶属于广域差分的星基差分(SBAS)系统。根据所在测区位置和定位精度要求的不同,海洋工程地震勘探选用不同的GPS定位设备可以接收不同系统提供的差分信号。导航软件也是海洋工程地震作业中必不可少的一部分,它不仅可以记录GPS定位设备的数据,还具有测线设计、坐标投影、航行轨迹显示等诸多功能。通过对导航软件的灵活应用和信号变换,导航软件还可以为地震系统提供触发信号。最后给出了一个海洋工程地震勘探实例。

The Differential Global Positioning System（DGPS） is indispensable to the seismic survey for offshore projects, which includes the Local Area DGPS and the Wide Area DGPS. The Radio Beacon（RBN） DGPS, one type of the Local Area DGPS, is usually and traditionally adopted for offshore survey. In contrast, the Satellite Based Augmentation System（SBAS）, one type of the Wide Area DGPS, is increasingly popular for the survey in which high position precision is expected or conducted in open sea. According to diverse survey positions and positioning accuracy requirements, different GPS positioning devices are selected for the seismic survey for offshore projects, so as to receive differential signals provided by different systems. A suit of navigation software is also essential to the survey, which can not only record GPS data, but also has a number of functions, including surveying line design, coordinate projecting and track display. By connecting the navigation computer and the seismic acquisition system with a level converter, the software can transfer trigger signals for seismic source excitation. Finally, a seismic survey instance is also provided in this paper.