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.
With my involvement in NRCan’s online PPP service, I get to see new trends in data submitted to our system. Until recently, dual-frequency GPS receivers could be categorized into two classes: the C1C/C2W and the C1W/C2W receivers. There is however another category of receivers that has attracted our attention lately: the ones tracking only the C1C/C2C signals.
Obtaining mm-level positioning accuracies with GNSS requires modeling of all error sources such as higher-order ionospheric effects. As a part of an IAG working group, I collaborated with European colleagues to investigate how this error source could be estimated as a part of the PPP filter. The results were published last week in GPS Solutions (Banville et al. 2017).
On June 19, Pierre Héroux officially retired from the Canadian Geodetic Survey of Natural Resources Canada (NRCan) after spending nearly 35 years with this organization. Over these years, Pierre has been a key player in the GNSS community, from testing the first commercial GPS receivers to being an early instigator of precise point positioning (PPP). Pierre kindly accepted my invitation to write a recollection of the early days of PPP and how this positioning methodology evolved within the IGS.
NRCan has been operating a zero-baseline GNSS calibration site on its premises for the past few months. The goal of this investigation is to better quantify the interoperability of different receiver/antenna types. Preliminary results obtained from this exercise were presented at the IGS workshop 2017 last week, and I thought that I would comment further on some of the Galileo results obtained.