Improved Ionospheric Modelling in Precise Global Navigation Satellite System Positioning

美国的GPS，即现在的全球导航卫星系统（GNSS），是一种无处不在的户外定位和导航方法。Hemisphere GNSS开发和销售高精度商业卫星定位/导航产品和服务，用于各种陆地和海洋应用。其中一项服务通过卫星通信链路向用户提供GNSS卫星轨道和时钟校正，从而实现所谓的实时精确点定位（PPP）。PPP测量处理技术有一些限制，为地球表面或以上任何地方的用户提供几厘米级的定位和导航能力，而未校正的GNSS则提供几米级的定位和导航能力。该公司有兴趣通过应用额外的电离层折射校正来改进其实时所谓的PPP GNSS测量处理用户服务。约克大学的GNSS实验室在PPP算法开发和误差建模方面拥有丰富的经验，已被要求支持半球完成这项复杂的任务。合并后的团队将：1)开发计算机代码，将电离层模型原型的修正纳入用户定位算法；2)改变算法的组成部分，以及随后的相关计算机代码，以充分利用这些修正；3)对修改后的用户定位方案性能进行测试。这两个小组将作为一个综合团队为这个项目工作，以增强半球软件，从而产生的软件技术将满足公司的要求，并产生一个联合研究出版物。半球GNSS公司作为加拿大高科技、高价值产品的出口商有着良好的记录，这笔拨款的结果将使这家创新型公司能够继续改进其产品，扩大其客户基础和市场。

The U.S. GPS, and now Global Navigation Satellite Systems (GNSS), is the ubiquitous method for outdoorpositioning and navigation. Hemisphere GNSS develops and sells high-accuracy commercial satellite-basedpositioning / navigation products and services for a wide variety of land and sea applications. One serviceprovides GNSS satellite orbit and clock corrections to users via a satellite communications link allowing forso-called real-time Precise Point Positioning (PPP). The PPP measurement processing technique, with a fewlimitations, provides few centimetre-level positioning and navigation capabilities to a user anywhere on orabove the surface of the Earth, as opposed to the few metre-level for uncorrected GNSS. The company isinterested in improving its real-time so-called PPP GNSS measurement processing user service by applying anadditional ionospheric refraction correction.The GNSS Laboratory at York University, with its extensive experience in PPP algorithm development anderror modelling, has been requested to support Hemisphere in this complex task. The combined team will: 1)develop computer code to incorporate corrections from a prototype ionospheric model into the user-positioningalgorithm; 2) alter components of the algorithms, and subsequently the relevant computer code, to make bestuse of these corrections; and 3) test the resulting user positioning solution performance post-modification. Thetwo groups will work as one integrated team for this project to enhance the Hemisphere software, so that theresulting software technology will satisfy the company's requirements and produce a joint research publication.Hemisphere GNSS has a proven track record as an exporter of high-tech, high-value Canadian products, andthe results of this grant will allow this innovative company to continue to improve its products and grow itsclient base and markets.