高灵敏度北斗B1I信号捕获技术研究

发布时间：2017-12-27 23:31

本文关键词：高灵敏度北斗B1I信号捕获技术研究　出处：《西安电子科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着人类活动范围的扩大,全球导航卫星系统越来越多的应用于室内定位、野外勘测、地震火灾救援、地理地形测绘等。在这些环境复杂的场景中,导航卫星的信号会受到诸如多径反射、障碍物遮挡、宽带干扰等多方面因素的影响而削弱,致使普通的接收机无法捕获到上述功率过低的卫星信号进行导航定位,限制了导航卫星系统的应用。高灵敏度导航卫星信号捕获是研究在弱信号环境下对导航卫星信号进行捕获的技术。北斗二号导航卫星系统是我国自主研制、独立运行的全球导航卫星系统。2012年,北斗正式进入商用阶段,目前在轨卫星19颗,已实现了亚太地区的导航定位服务。随着北斗系统的不断完善,北斗导航定位终端拥有极为广阔的市场前景。因此,高灵敏度北斗卫星信号捕获技术是一项非常具有挑战性和前瞻性的研究课题。本文首先对北斗二号卫星信号的结构和特性进行了分析,包括信号的组成结构、测距码的产生和性质、卫星信号的多普勒效应以及中频信号模型等,并设计实现了北斗中频信号仿真程序,详细介绍了仿真中频信号的产生流程。然后介绍了导航卫星信号的捕获原理和分别在时域和频域进行的两种基本的捕获方法。其次,实现高灵敏度导航卫星信号捕获主要是对本地复现信号和接收卫星信号的相关结果进行积分,根据累积方式的不同,分为相干积分法、非相干积分法和差分相干积分法,本文详细介绍了三种算法的原理,并对其进行了仿真分析,仿真实验表明由于北斗信号比特反转速率高,使得相干积分的时间不能超过1ms,差分相干积分法也并不适用。本文分析了非相干积分法和全比特法两种北斗弱信号捕获方法,对其捕获性能进行了仿真分析。针对高灵敏度捕获算法运算量大,运行时间长的问题,提出了一种优化方法,使一个测距码周期的相关运算可以减少一半的傅里叶逆变换和一半的相乘运算。最后,本文设计了一种适用于北斗卫星B1I弱信号的捕获方法,即改进半比特-特征序列法。通过实验验证了改进半比特算法的可行性,并详细分析了不同长度的NH20码特征序列的抗干扰能力。使用仿真北斗中频信号对该方法进行了捕获实验,并与非相干积分法和全比特法做了捕获性能对比,实验表明本文设计的方法的捕获性能优于非相干积分法和全比特法。然后,用本文设计的方法对卫星中频信号采集系统采集到的真实的北斗卫星信号进行了捕获实验,成功捕获到了真实的北斗卫星弱信号。
[Abstract]:With the expansion of the scope of human activities, the global navigation satellite system is more and more applied in indoor location, field survey, earthquake fire rescue, geographic and topographic mapping, etc. In these complex scenarios, such as signal of navigation satellite will be affected by multipath reflection, obstructions, broadband interference factors weakened, resulting in the common receiver cannot capture the satellite signal of the power is too low for navigation and positioning, which restricts the application of navigation satellite system. High sensitivity navigation satellite signal acquisition is a technology to capture navigation satellite signals in weak signal environment. Beidou two navigation satellite system is a global navigation satellite system, which is independently developed and independently operated in China. In 2012, the dipper formally entered the commercial phase. At present, 19 satellites on orbit have realized the navigation and positioning service in the Asia Pacific region. With the continuous improvement of the Beidou system, the Beidou navigation and positioning terminal has a very broad market prospect. Therefore, the high sensitivity Beidou satellite signal acquisition technology is a very challenging and forward-looking research topic. Firstly, on the structure and characteristics of the two satellite signals are analyzed, including the structure of the Doppler effect, ranging code signal generation and properties, the satellite signal and signal model, and the design and implementation of Beidou signal simulation program, the paper introduces production process simulation of the intermediate frequency signal. Then it introduces the acquisition principle of navigation satellite signals and two basic acquisition methods in time domain and frequency domain respectively. Secondly, to achieve high sensitivity navigation satellite signal acquisition is mainly related to the local replica signal and receiving satellite signals are integrated according to the accumulation of different, divided into coherent integration, non coherent integration method and differential coherent integration method, this paper introduces the principle of three algorithms, and its simulation analysis and simulation results show that the Beidou signal bit reversal rate is high, the coherent integration time is no more than 1ms, the differential coherent integration method is not suitable. In this paper, two Beidou weak signal acquisition methods are analyzed, which are incoherent integration and full bit method, and their capture performance is simulated and analyzed. Aiming at the problem of large amount of computation and long running time of high sensitivity acquisition algorithm, an optimization method is proposed to reduce the correlation operation of a ranging code cycle by half and half the multiplication operation. Finally, this paper designs a method to capture the weak signal of the Beidou satellite B1I, that is, the improved half bit - feature sequence method. The feasibility of the improved half bit algorithm is verified by experiments, and the anti-interference ability of the NH20 code feature sequences with different lengths is analyzed in detail. The simulation of Beidou intermediate frequency signal is used to capture the experiment, and the acquisition performance is compared with the incoherent integration method and the full bit method. The experimental results show that the acquisition performance of the proposed method is better than the non coherent integration method and the full bit method. Then, the real Beidou satellite signal collected by the satellite if signal acquisition system is captured by the method designed in this paper, and the real Beidou satellite's weak signal is successfully captured.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN967.1

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