The World’s first GPS MOOC and Worldwide Laboratory using Smartphones

Frank van Diggelen and Per Enge

Abstract: This paper describes the experiences and results of the first GPS MOOC (Massive Open Online Course), including a worldwide laboratory involving thousands of participants. MOOCs have the potential to revolutionize education in the same way that the Internet has forever changed other industries. A MOOC is a free online course, typically with thousands of participants from all over the world. In this talk we describe the first GPS MOOC. This MOOC “GPS: An Introduction to Satellite Navigation” was created by the authors for Stanford University, and is hosted by Coursera. The course ran for the first time in the last quarter of 2014, and will run again in 2015, starting shortly after the ION GNSS+ conference. Participation in 2014 was astonishing: we had over 31,000 registrants from 192 different countries (for comparison: the UN has 193 member states). Of these registrants approximately six-thousand participated regularly in the class; three-thousand completed the whole course; and seventeen hundred participated in the handson labs. This MOOC was the first to make use of smartphones to create a worldwide laboratory for experiments conducted by the students. Since each smartphone contains a GNSS receiver, students could get hands-on experience, while at the same time collecting data on an unprecedented scale. The main idea of the laboratory was pedagogical: to teach the students about GNSS, and so the labs were conceived to be relatively simple. But the sheer scale of the class was such that we obtained very interesting results which we will present in this paper for the first time. The first lab studied GNSS accuracy, as experienced by smartphone users, both in the open and in urban environments. Open-sky GNSS accuracy with smartphones has often been claimed to be “about 5 meters”, in fact this was the answer to an in-course quiz question in one of the lectures. In this lab, with over one thousand participants in one hundred countries, the measured mean accuracy, remarkably, came to 4.9 meters. Even more interesting, the accuracy in urban areas showed a remarkable correlation with building height. So well correlated, in fact, that we are moved to propose a “Law of Urban Multipath” that predicts GNSS position accuracy based on building height. We will explain this result in the paper, and show the data distributions supporting it. In the second lab, the students performed mission planning to predict when a particular satellite would pass (close to) overhead on one particular day. They then had to go outside at that time, and see if the GNSS receiver observed the satellite where it was expected. They recorded the time, their location, and where in the sky the satellite was observed. They then submitted this data online. Each student becoming part of a worldwide relay. As the data came in, they could tell who saw the satellite before them, and who would see it next. This was a memorable experience for everyone, linking people from a hundred different countries with no regard for borders or boundaries of any kind In the third lab we returned to quantitative analysis of GNSS. Students, after learning about GNSS Front End analysis, compared the measured C/No in their phones to the expected value for a nominal design. Thus they characterized the RF performance of the GNSS in many of the world’s most popular smartphones. Following this, they repeated the experiment in their homes, thus characterizing the signal loss through the different types of buildings. We collected this data and will present the results for the first time in this paper. We believe that this is the first time that experimental data like this has been collected on this scale. The results are interesting in their own right, while also a vision for what might be achieved with a worldwide team of highly motivated volunteers who will together collect data in more environments in a day than most of us will visit in a lifetime. Based on the success of this first MOOC, we are modifying the labs for the 2015 edition to collect more detailed data that will shed further light on the operation of GNSS worldwide. In the paper we will discuss the plans for future labs, and we welcome input from the ION community for ideas about what may be measureable, and what we can yet discover about our GNSS ecosystem.
Published in: Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015)
September 14 - 18, 2015
Tampa Convention Center
Tampa, Florida
Pages: 361 - 369
Cite this article: van Diggelen, Frank, Enge, Per, "The World’s first GPS MOOC and Worldwide Laboratory using Smartphones," Proceedings of the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2015), Tampa, Florida, September 2015, pp. 361-369.
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