The Research on Indoor High Accuracy Frequency Source Based on Adaptive Loop Adjusting
China will establish the Xihe System based on Beidou/GNSS, Mobile Communication, Internet and Satellite Communication system to realize the Seamless Outdoor and Indoor Positioning in Wide Area (SOIPWA) on personal mobile terminals. Indoor Positioning Syst
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The Research on Indoor High Accuracy Frequency Source Based on Adaptive Loop Adjusting Zhongliang Deng, Xu Li and Xie Yuan
Abstract China will establish the Xihe System based on Beidou/GNSS, Mobile Communication, Internet and Satellite Communication system to realize the Seamless Outdoor and Indoor Positioning in Wide Area (SOIPWA) on personal mobile terminals. Indoor Positioning System (IPS) is one of the main components and effective supplement for indoor positioning signal resource to resolve the positioning signal coverage of blind areas in complicated indoor environment based on current 2G/3G communication network and existing equipment. According to the requirement, the IPS adopted the unified time-frequency reference which affects the accuracy of indoor positioning directly. This paper provides an acquisition method of high accuracy frequency source used in the indoor positioning signal supplement. Positioning signals from outdoor base stations are acquired by RF front end and tracked by the carrier loop and code loop adjusting. After that, positioning signals are locked and synchronized to extract the high accuracy frequency source used for IPS, which can be built with low cost and precisely integrated with an outdoor positioning system. In practical test, the method satisfies the need of the accuracy and stability in time-frequency reference for IPS with high frequency accuracy, quick start and low drift rate through adjusting high accuracy Voltage Controlled Oscillator (VCO) by Digital to Analog Converter (DAC) with the frequency difference result from the adaptive loop. Keywords Indoor positioning adjusting
Time-frequency reference
Adaptive loop
Z. Deng X. Li (&) X. Yuan Beijing University of Posts and Telecommunications, Xitucheng Road 10, Beijing 100876, China e-mail: [email protected]
J. Sun et al. (eds.), China Satellite Navigation Conference (CSNC) 2013 Proceedings, Lecture Notes in Electrical Engineering 245, DOI: 10.1007/978-3-642-37407-4_47, Ó Springer-Verlag Berlin Heidelberg 2013
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47.1 Introduction IPS adopts the unified time-frequency reference to ensure the high accuracy in indoor positioning. It is restricting development of indoor LBS that how to find a well-performance time-frequency reference with low cost. GPS, Beidou and other satellite navigation system could be applied to adjust local oscillator to promote accuracy and stability with time service in [1]. This method had some limitation in some places like canyon areas in downtown where satellite signal is too weak to be received and security problem exists additionally. To problems in [1], method in [2] provided another approach that combine the CAPS in space with Rubidium clock on ground to acquire high accuracy and well stable time-frequency reference, but obviously the cost is main obstacle to take into practice in large scale. In this paper, an acquisition method of high accuracy frequency source applied in IPS was introduced where local Temperature Compensate X’tal (crystal) Oscillator (TC
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