I love blogging: it is a quick and interactive way of expressing my views on GNSS, getting feedback and moving things forward. The blackdotgnss.com project started nearly four years ago and it grew considerably, from one follower (thanks Richard!) to over 100 mailing-list subscribers and over 300 followers on Twitter. Unfortunately, all good things come to an end.
The IGS Workshop 2018 was held from 29 October to 2 November in Wuhan, China. One of the focus of the workshop was to align efforts towards incorporating multi-GNSS products in the standard line of IGS products. As a bonus, we might even see products enabling PPP with ambiguity resolution (PPP-AR) in a not-so-distant future!
At the ION GNSS+ 2018 conference, I presented a paper based on a joint effort between NRCan and Swift Navigation on network modelling considerations for wide-area ionospheric corrections. Both organizations had similar questions regarding this topic: what is the recommended station density to reach cm-level ionospheric corrections? And is it better to use a 3D model or a per-satellite model? This blog post summarizes our findings.
From 24-28 September was the ION GNSS+ meeting held in Miami, Florida. Evolutions in the conference name (now including the “+”) are well reflected in the content. Research on precise point positioning (PPP) is now driven by the automotive industry which calls for less stringent accuracy needs but higher integrity. This blog post summarizes what I consider to be the key points of the conference from a PPP perspective, with an emphasis on low-cost devices and integrity.
Precise point positioning (PPP) requires careful modeling of several error sources affecting GNSS observations. Additionally, consistency between the network and user software is essential to obtain the upmost accuracy. Unfortunately, an inconsistency affecting the CSRS-PPP software has been causing, for a few years now, a height bias of several millimeters.
The online PPP service offered by the Canadian Geodetic Survey of NRCan has been available since 2003. It processes, on average, about 1000 RINEX files daily, fulfilling the positioning needs of Canadians and the international community. The PPP landscape having evolved significantly in the last few years, the underlying PPP engine will be replaced by a new version on August 14th 2018.
When I first got involved in GNSS, more than a decade ago, my objective was to reduce the convergence time of PPP solutions. In the past few years, I witnessed this methodology evolve and fast convergence became possible using ambiguity resolution and external atmospheric data. The upcoming years will be a game changer in this area: with GNSS modernization, instantaneous PPP convergence will be possible even without any reference stations nearby.
A few months ago, I embarked on a new journey hoping to make a contribution to autonomous driving. While it has been a very beneficial experience, the position was just not the right fit for me. Hence, I will be resuming my activities with NRCan next week as well as my semi-regular blogging. Meanwhile, here are 5 lessons learned from my journey that I hope everybody can benefit from.
A few months ago, I highlighted an erratum from the Springer Handbook of Global Navigation Satellite Systems. The chapter on Differential Positioning accused myself and my colleagues at NRCan of making false claims about the applicability of our new approach to GLONASS ambiguity resolution. Contacting the editors did not lead to any hope of having this issue promptly resolved, so we decided that a follow-up paper on this topic was in order to better clarify the intricacies of our approach.
Precise point positioning (PPP) has evolved significantly in the last decade. The long convergence times of PPP solutions were drastically reduced thanks to ambiguity resolution capabilities and precise STEC corrections. Low-cost GNSS positioning also matured significantly and high-precision positioning with a smartphone is now possible. These innovations are triggering a revolution in satellite-based positioning and I decided that the time has come to jump ship and leave my position at NRCan.