Space Time Characteristics of the RF Absolute Power of Indoor GPS Signals

Y. Aiga, K. Washizu, M. Nakamura, K. Sorita, M. Shoji, Y. Ogasa

Abstract:	The GPS technology has been employed for various applications. Recently, some applications are developed for outdoor and indoor use, as represented by E-911 in U.S. The indoor characteristics of GPS signals differ from outdoor ones, because the indoor signals are disturbed by walls, windows, etc. The analysis of indoor characteristics is very important to design antennas and signal processing methods for indoor applications. It is known that GPS signals penetrating through a wall are much weaker than those penetrating through a window. However, the indoor characteristics of RF absolute powers of GPS signals are scarcely understood because the indoor characteristics have hardly been reported. For this reason, the characteristics of the RF absolute powers should be clarified. We measured the RF absolute signal powers inside a building by changing antenna positions and antenna beam directions. The measurement system consisted of a high-sensitivity GPS receiver we developed and two types of antenna. Our GPS receiver achieved over -160 dBm of RF sensitivity to acquire weak indoor signals. We used a normal antenna and a narrow-beam antenna. The narrow-beam antenna was used for clarifying the directional dependency of the GPS signals. In addition, we calibrated our GPS receiver with a GPS simulator to obtain the actual RF absolute powers. We clarified the space time characteristics of the RF absolute powers of indoor GPS signals by statistically analyzing the measured data. We are convinced that our results are useful for optimal design of antennas and signal processing methods for indoor GPS applications.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	1149 - 1157
Cite this article:	Aiga, Y., Washizu, K., Nakamura, M., Sorita, K., Shoji, M., Ogasa, Y., "Space Time Characteristics of the RF Absolute Power of Indoor GPS Signals," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 1149-1157.
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