News Column

New Findings from Seoul National University in the Area of Sensor Research Reported

June 17, 2014

By a News Reporter-Staff News Editor at Journal of Technology -- Current study results on Sensor Research have been published. According to news reporting originating from Seoul, South Korea, by VerticalNews correspondents, research stated, "The ephemeris data format of legacy GPS receivers is improper for positioning stationary pseudolites on the ground. Therefore, to utilize pseudolites for navigation, GPS receivers must be modified so that they can handle the modified data formats of the pseudolites."

Our news editors obtained a quote from the research from Seoul National University, "Because of this problem, the practical use of pseudolites has so far been limited. This paper proposes a pseudolite-based positioning system that can be used with unmodified legacy GPS receivers. In the proposed system, pseudolites transmit simulated GPS signals. The signals use standard GPS ephemeris data format and contain ephemeris data of simulated GPS satellites, not those of pseudolites. The use of the standard format enables the GPS receiver to process pseudolite signals without any modification. However, the position output of the GPS receiver is not the correct position in this system, because there are additional signal delays from each pseudolite to the receiver. A post-calculation process was added to obtain the correct receiver position using GPS receiver output. This re-estimation is possible because it is based on known information about the simulated signals, pseudolites, and positioning process of the GPS receiver. Simulations using generated data and live GPS data are conducted for various geometries to verify the proposed system. The test results show that the proposed system provides the desired user position using pseudolite signals without requiring any modifications to the legacy GPS receiver. In this initial study, a pseudolite-only indoor system was assumed."

According to the news editors, the research concluded: "However, it can be expanded to a GPS-pseudolite system outdoors."

For more information on this research see: A pseudolite-based positioning system for legacy GNSS receivers. Sensors, 2014;14(4):6104-23. (Elsevier -; Sensors -

The news editors report that additional information may be obtained by contacting C. Kim, School of Mechanical and Aerospace Engineering and the Institute of Advanced Aerospace Technology, Seoul National University, Daehak-dong, Kwanak-gu, Seoul 151-744, South Korea. Additional authors for this research include H. So, T. Lee and C. Kee.

Keywords for this news article include: Asia, Seoul, South Korea, Sensor Research.

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Source: Journal of Technology

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