Inside GNSS Media & Research

SEP-OCT 2018

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34 Inside GNSS S E P T E M B E R / O C T O B E R 2 0 1 8 Professional Path Anna Jensen began working in GNSS in 1994 and has had a remarkable professional career. "When teaching," she told Inside GNSS, "I often introduce myself to the students with a summary of my employment record, because it is unusual." In addition to starting and operating a consulting company (AJ Geomatics, 2006-present), Jensen has been employed by: • A private company (GPService, Denmark, 1994); • A government organization (National Survey and Cadastre, Denmark, 1995-2003); and • Two different universities (Technical University of Den- mark, 2003-2006; KTH Royal Institute of Technology, Swe- den, 2014-present) Jensen has worked on air navigation, land surveying, vehicle navigation and geodynamic monitoring, to mention just a few applications. "I have also taught and supervised and have been both project manager and manager of personnel," she said. "All these assignments have revolved around GNSS. So even though it may seem a bit 'messy' there is a red line of GNSS running through my CV." Engineering Specialties It all started with a firm background in geodesy and land survey- ing. Jensen is specialized in GNSS high-accuracy positioning algo- rithms, and atmospheric effects on GNSS satellite signals. Other Technologies GNSS has been the central technology though most of Jensen's career. "But in the late 1990s," she said. "I worked with classical geodesy, mostly coordinate transformations and map projec- tions." In more recent years, geodata quality has become an impor- tant topic in her work. "GNSS can provide good and reliable posi- tions, but we also need good and reliable maps and other geo- data in order to make full use of GNSS in many applications." Engineering Mentor(s) There have been a number of people who Jensen can name as her mentors. First of all, there was her father: "I grew up in the countryside, and he taught me to be around machines. He had a master's degree in agriculture and he was also the one who taught me how to use a computer. "My physics teacher in high school, Mr. Erling Baastrup, made me believe that you can understand how most things work if you study hard enough. Today, this belief has faded, but it was a really good mindset to have as a student. Also, he introduced our class to computer programming, which was very novel in high school in the mid 1980s. "Professor Cannon from the University of Calgary, who co- supervised my Ph.D., played an important role. Although I had already been at university for four years when I first met her, she was the first female professor I had ever encountered. "And then there is Professor Lachapelle in Calgary, and the late Professor Tscherning at the University of Copenhagen, who were very important mentors, providing supervision, advice and sup- port in the early years of my career." GNSS Event that Most Signified to You that GNSS had 'Arrived' Jensen understood that GNSS had become a societal reality when, "Once, at a dinner party in 1997, I was seated next to a plumber who was also a recreational sailor. After I had told him I worked with GPS, he spent the next half hour explaining to me how GPS works. Of course I knew it already, but I was very surprised at how much he, as a layman, knew about the GPS satel- lites and signals." What Popular Notions About GNSS Most Annoy You? Anna Jensen gets miffed when people blame GNSS for mistakes that are actually caused by errors in a map, chart or 3D city model. "There has been too little focus on the map side of navigation," she said, "probably because GNSS has been more 'hot' to work with. This is one of the reasons why my research group has now taken up work with geodata quality." As a Consumer, What GNSS Product, Application, or Engineering Innovation Would You Most Like to See? Jensen looks forward to the day when commercial centimeter- level carrier-phase-based positioning will be available in smart- phones, which, by the way, she believes is just around the corner. "Also," she said, "I find the use of GNSS in space exciting, and there is more to do in that field. By space I mean the use of GNSS outside the GNSS orbits i.e. at altitudes of 20,000 kilometers and beyond. This does not really affect myself as a consumer, but for future commercial travel to the moon it may be relevant." Favorite Equation The carrier phase observation equation: Φ = ρ + c(б r – б s ) + λN + υ Where: Φ is measured phase observation in meter ρ is geometric distance between receiver and satellite c is speed of light б r , б s are receiver and satellite clock errors λ is signal wave length N is carrier phase ambiguity υ covers all error sources like atmospheric effects, uncertain- ties in satellite positions, antenna phase center variation, multipath, signal biases etc. "The interesting part is the last term," Jensen said. "Based on the application and the required positioning uncertainty, the term can be expanded into many elements which can be modeled and estimated separately, for instance the effects on signal propaga- tion caused by ionosphere and troposphere." Compass Points within the fields of GNSS and tradi- tional geodesy." Currently, Jensen is running two different projects on geodata quality. One is funded by the Swedish research council and the other is by the Swed- ish Transport Administration. Also, a recently completed project on GNSS and network optimization was carried out in cooperation with the company WSP Sweden. Professor Jensen takes her role as an academician very seriously, as a teacher and supervisor at all university levels. And, she says, her work for educational institutions goes well beyond the class- room. "I believe it is important that we, at universities, cooperate with key players in civil society in order to see and understand current challenges," she said. "So for me it is a thrill to have HUMAN ENGINEERING

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