Sensors 2014, 14(4), 6104-6123; doi:10.3390/s140406104
Article

A Pseudolite-Based Positioning System for Legacy GNSS Receivers

1email, 2email, 3email and 1,* email
Received: 2 December 2013; in revised form: 17 March 2014 / Accepted: 18 March 2014 / Published: 27 March 2014
(This article belongs to the Section Remote Sensors)
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Abstract: 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. 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. However, it can be expanded to a GPS-pseudolite system outdoors.
Keywords: GPS; pseudolite; indoor navigation
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Kim, C.; So, H.; Lee, T.; Kee, C. A Pseudolite-Based Positioning System for Legacy GNSS Receivers. Sensors 2014, 14, 6104-6123.

AMA Style

Kim C, So H, Lee T, Kee C. A Pseudolite-Based Positioning System for Legacy GNSS Receivers. Sensors. 2014; 14(4):6104-6123.

Chicago/Turabian Style

Kim, Chongwon; So, Hyoungmin; Lee, Taikjin; Kee, Changdon. 2014. "A Pseudolite-Based Positioning System for Legacy GNSS Receivers." Sensors 14, no. 4: 6104-6123.


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