The Next Generation of a Super Sensitive GPS System

Lawrence R. Weill, Nobuhiro Kishimoto, Seiichiro Hirata and Kevin Xinhua Chin

Abstract:	This paper describes the next generation of a super sensitive assisted GPS system for C/A coded signals that was originally developed by Magellan Systems Japan, Inc. in collaboration with a Japanese electric company and Thales Navigation. The improved system is designed to provide rapid positioning in weak signal areas, such as inside buildings. In addition to other applications, a primary goal is to embed the client receiver in cell phones to enable rapid location in an emergency such as a 911 call. Proprietary techniques have been developed to obtain the following improvements: 1. Low-latency time coordination between the client receiver and the assisting base station (server) is not required. 2. High sensitivity is maintained with a short signal capture time and without the need to know the navigation message bit sequence from any external source. 3. The local oscillator frequency offset at the client receiver can be estimated efficiently, thus reducing the cost of the local oscillator and eliminating the need for an accurate frequency reference transmitted by the server. These and other improvements permit existing communication systems, such as cell phone networks, security systems, and the internet, to transmit assisting information to the client receiver with only a simple communication interface to a reference GPS receiver. No major modifications to the communication system are required, which is a significant advance in the state of the art of assisted GPS systems. Theoretical design considerations and preliminary test results of the improved high sensitivity system are presented in this paper.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	1924 - 1935
Cite this article:	Weill, Lawrence R., Kishimoto, Nobuhiro, Hirata, Seiichiro, Chin, Kevin Xinhua, "The Next Generation of a Super Sensitive GPS System," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 1924-1935.
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