Research and Performance Analysis of Constant-Envelope Multiplex for BD B2 Signals
AltBOC (15, 10) is proposed to be the modulation mode of BD B2 global signals, which combines lower and upper lobes with four signals. The modulation makes users able to receive and process one lobe separately, or process two lobes coherently to achieve h
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Abstract AltBOC (15, 10) is proposed to be the modulation mode of BD B2 global signals, which combines lower and upper lobes with four signals. The modulation makes users able to receive and process one lobe separately, or process two lobes coherently to achieve higher accuracy of position and navigation. AltBOC could also fulfill compatibility among BD, Galileo E5, and GPS L5. There have been lots of researches of B2 signals’ solutions currently, but most of these only considered four signals with the same modulation mode and chip rate, which makes the choice of signals inflexible. Thus, we present two kinds of conditions that B2 signals have different modulation methods and chip rate, and three kinds of constant-envelope multiplex plans based on it to realize AltBOC modulation: non-symmetrical AltBOC, TD-AltBOC, and binary TD-AltBOC. The multiplex plans are simulated and multiplex efficiency of each one is given. Also the ranging accuracy, anti-multipath resistant, and anti-interference performance is shown to compare the three signals with the multiplex signals of B2 signals which are modulated as AltBOC (15, 10). Analysis results show the signals of the three multiplex plans have similar ranging accuracy, anti-multipath resistant, and anti-interference performance with the AltBOC (15, 10) signals. TD-AltBOC has the highest multiplex efficiency that is 100 % among the three plans. The multiplex schemes we present are able to combine signals with different modulation methods and chip rate as AltBOC modulation, which can achieve the same navigation performance to AltBOC (15, 10) signals and high multiplex efficiency, and these schemes could be new solutions for BD B2 signals.
Keywords BD Constant-envelope multiplex AltBOC Performance evaluation
M. Cai (&) N. Qi China Academy of Space Technology, Xi’an Branch, Xi’an, China e-mail: [email protected] J. Xie China Academy of Space Technology, Beijing, China © Springer Science+Business Media Singapore 2016 J. Sun et al. (eds.), China Satellite Navigation Conference (CSNC) 2016 Proceedings: Volume II, Lecture Notes in Electrical Engineering 389, DOI 10.1007/978-981-10-0937-2_5
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1 Introduction In 2001, CNES presented the AltBOC constant envelope modulation mode of four signals, realized four signals multiplex in two different frequency points, which was selected as Galileo E5 band signal modulation mode [1]. Because of the flexible use of AltBOC and considering the compatibility of GPS L5 and Galileo E5, BD global navigation satellite system is proposed AltBOC (15, 10) as B2 signal modulation mode. The center frequency of AltBOC (15, 10) signal is located in the center of 1191.795 MHz, lower sideband at 1176.45 MHz, the same with GPS L5C and Galileo E5a, and upper sideband is located at 1207.14 MHz, the same with Galileo E5b. Upper and lower sideband contains data channel and pilot channel, each channel has the same energy [2]. There have been lots of researches on B2 frequency signal realization, such as TD-AltBOC proposed by Tang [3], an
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