| Binary Offset Carrier (BOC) modulation is a kind of signal modulation used in the new generation of satellite navigation system. It is both applied to GPS modernization and the European Union Galileo system. BOC modulates special spectrum and correlative characteristic, thus BOC modulation has the good performance of anti-noise and anti-multipath interference. The Galileo system is completely civil-oriented satelite navigation system developed by the European Union Organization. It has broard development and application prospect and is under implementation now. So it is of great significance to the research on Galileo system signal.The L1F frequency's BOC(1,1) modulation signal of the Galileo system is taken as the object of study in the dissertation, and the spread spectrum signal synchronization technology modulated by BOC is discussed thoroughly. Firstly the space part, the ground control part, the user equipment part and the characteristic of Galileo satellite navigational system are introduced in the dissertation, and the BOC modulation principle, the signal frequency characteristic and the signal generation are mainly studied. Then the synchronization of navigation signal(including acquisition and tracking) is studied in detail. The navigational signal acquisition principle and the common acquisition methods are introduced, and then the acquisition scheme of BOC(1,1) signal is proposed and verified about its effect. In the signal tracking part, the digital non-coherent doubleΔDLL algorithm and several code delay tracking loop discriminators are analyzed, and then BOC(1,1) signal code tracking scheme and PLL design scheme are put forward and varified about their performance. In the system measure error and tracking threshold part, the effect on synchronization performance caused by thermal noise and dynamic error are discussed and the carrier assistant tracking scheme is put forward in the dissertation.The exact method of BOC(1,1) signal tracking proposed in the dissertation is called Autocorrelation Side-Peak Cancellation Technique. The principle of ASPeCT is to eliminate the multimodality of signal autocorrelation function by designing a definite compound correlation function. Two discriminator algorithms based on ASPeCT are studied, and the output error characteristics of the two discriminators are fully simulated. Then the signal acquisition scheme based on ASPeCT is designed and the simalation is made about its performance. From the comparison, the ASPeCT technology improves the accuracy of BOC(1,1) signal synchronization obviously. |
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