新型卫星导航信号接收模糊减轻技术研究

The new satellite navigation signals such as BOC and the extended signals are widely applied to the global navigation satellite system，mitigating or eliminating the ambiguity for BOC signals acquisition and tracking effectively is the prerequisite for exerting the inherent high accuracy and anti-multipath advantages of BOC signals.?Now the researches on mitigating or eliminating the ambiguity for the CosBOC and ALTBOC signals are relatively limited and need to be solved imminently. For this reason,the current project is carried out in accordance with the following steps.(1)For the CosBOC and ALTBOC signals, the multilevel auxiliary reference signal is constructed by choosing the minimum rectangle unit in the time domain as the reference waveform and pending the wave vector, then they are cross-correlated with the receiving signal. This method avoids excessively increasing complexity of receiver.(2)According to the receiver structure and cross-correlation function, the evaluation indexes about the ambiguity mitigating degree, probability of acquisition and tracking precision are proposed, and the corresponding analytical expressions are calculated.(3)The intelligent multi-objective optimization algorithm is investigated. The ambiguity mitigating degree is defined as the objective function and the capture probability and tracking accuracy are defined as the constraint conditions respectively, and then the waveform vector of the local multilevel auxiliary reference waveform is acquired by using the multi-objective optimization algorithm. This project can solve the ambiguity in the capturing and tracking for CosBOC and ALTBOC signals, and also can guarantee the optimal overall system performances simultaneously. The project has practical engineering significance in satellite navigation field.

新型卫星导航信号BOC及其扩展信号广泛应用于全球导航卫星系统中，减轻BOC信号的捕获和跟踪模糊，是有效发挥其高精度和抗干扰优点的前提条件。目前关于CosBOC和ALTBOC信号的模糊减轻技术研究相对薄弱，是亟待解决关键难题。有鉴于此，本项目按照以下步骤展开:（1）针对CosBOC和ALTBOC信号，以时域码片波形最小矩形单元为基准波形，待定波形向量，构造多电平辅助参考信号，与接收信号进行互相关，避免了过度增加接收机复杂度。（2）根据接收机结构和互相关函数，提出能准确反映模糊减轻能力、捕获概率和跟踪精度的评价指标，并求出其相应的解析表达式。（3）研究多目标智能优化算法，以模糊减轻能力作为目标函数，以捕获概率和跟踪精度作为约束条件，运用多目标优化算法求解出本地多电平辅助参考波形的波形向量。本项目可解决CosBOC和ALTBOC信号的捕获和跟踪模糊，同时可保证系统性能总体最优，具有实际工程意义。

二进制偏移载波（Binary Offset Carrier, BOC）信号调制广泛应用于全球导航卫星系统中，减轻BOC信号的跟踪模糊和提高其抗多径干扰能力是有效发挥其高精度定位的关键环节。本项目研究正弦相位二进制偏移载波调制(Sine-phased BOC，SinBOC)、余弦相位二进制偏移载波调制（Cosine-phased BOC, CosBOC）和交替偏移载波调制（Alternative BOC, AltBOC）的跟踪模糊减轻和抗多径干扰技术，并分析了相关性能。. 在跟踪模糊减轻方面：针对AltBOC信号和CosBOC信号各提出了一种基于伪相关方法的本地参考波形设计方法，有效地解决了其跟踪模糊问题，跟踪性能和抗多径干扰性能整体上优于BPSK方法；针对CosBOC信号基于加权组合相关函数，采用最小二乘法优化目标获得加权系数，以产生无模糊跟踪函数，完全消除CosBOC信号的跟踪模糊，同时保留其尖锐主峰，使其保持了良好的跟踪性能，且对中等和较长多径干扰有良好的抗多径能力。. 在抗多径干扰方面：针对SinBOC信号提出了码相关参考波形方法，消除了跟踪模糊同时能较好地抑制中长延迟多径信号的干扰；研究了基于多门延迟结构方法对多径干扰抑制效果，推导了带宽受限时多门延迟结构的多径误差的数学表达式，以多径误差包络面积最小作为目标函数，优化了该结构中早迟门系数，并通过数值仿真结果表明该方法的多径干扰抑制能力整体上优于窄相关和高分辨率相关器方法。. 另外，研究北斗卫星导航原理的并搭建一种基于SOC硬件平台的导航接收机系统。实验测试接收机定位精度与手机GPS定位精度相当。. 以上研究结果均可以应用于北斗、GPS和Galileo系统中相关信号上，具有较好的科学意义和应用价值。