16. November 2019
To obtain the highest accuracy from precise point positioning (PPP) solutions, consistency between network and user algorithms must be ensured. An error source prone to mismodelling is satellite attitude, especially during eclipse periods. This blog post explains how to use data from an attitude exchange format being tested within the IGS.
13. October 2019
The annual ION GNSS+ meeting was held in Miami, Florida, from September 16 - 20, 2019. I was surprised, and initially disappointed, that there was no session dedicated to precise point positioning (PPP) this year. However, it quickly became clear that PPP-related research is still going strong: it has simply evolved to focus on low-cost GNSS devices, smartphones and integrity.
07. September 2019
While writing my ION GNSS+ 2019 paper, I realized I should use some sort of checklist to ensure that my work meets basic quality requirements. I may sound like I have been brainwashed by ISO certification but, especially as a reviewer, I wish everybody would follow this checklist to the letter. This is still work in progress, so if you can contribute further advice, please feel free to leave a comment!
18. August 2019
Will PPP ever replace RTK? Over the past decade, we have seen the convergence of PPP and RTK towards “PPP-RTK,” where satellite orbit/clock/bias corrections are augmented by local atmospheric corrections to enable instantaneous convergence to cm-level accuracies. But how close are we to instantaneous cm-level PPP-AR, without local augmentation?
02. August 2019
After an 8-month interruption, I am thrilled to announce that the BlackDotGNSS blog is back! While management was supportive of this initiative, issues were raised by the ethics committee regarding information sharing and it was recommended to abort this activity. I recently had the opportunity to have a face-to-face discussion with members of this committee, and I learned that blogging is allowed under certain conditions.
04. December 2018
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.
07. November 2018
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!
13. October 2018
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.
01. October 2018
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.
03. August 2018
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.

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