Method for eliminating pseudolite near-far effect based on orthogonal subspace projection
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摘要: 针对地基伪卫星系统中接收机受到远近效应影响无法正确捕获远场伪卫星信号这一问题，引入了基于正交子空间投影算法的捕获优化方法. 该方法应用于码分多址伪卫星信号，通过常规滑动相关法得到的强信号码相位和多普勒频移计算正交投影算子，将接收信号与其在强信号空间的投影相减得到弱信号空间并重新进行捕获，以消除强信号对弱信号的干扰. 实验结果表明：强弱信号在小于30 dB的功率比范围内，应用正交子空间投影法可以有效改善弱信号捕获性能. 这对拓宽地基伪卫星系统的有效工作范围、提升伪卫星接收机信号功率比容忍限度具有重大意义.
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关键词:
- 地基伪卫星系统 /
- 码分多址(CDMA) /
- 远近效应 /
- 正交子空间投影 /
- 弱信号捕获概率
Abstract: Receivers in ground-based pseudolite systems are often affected by the near-far effect, causing failure acquisition of far-field pseudolite signals. An optimization method based on orthogonal subspace projection is introduced in this paper, which is applied to code division multiple access (CDMA) pseudolite signals. Firstly, strong-signal code phases and Doppler frequencies are obtained through conventional sliding correlation to calculate the orthogonal projection operator. Then the weak-signal space is obtained by the received signal subtracting its projection in the strong-signal space. Finally, the re-acquisition is done in the weak-signal space to eliminate of the interference of strong signals. The experimental result indicates that the orthogonal subspace projection can effectively improve weak-signal acquisition performance in the power ratio range of lower than 30 dB, which is of great importance to widen the effective working range of ground-based pseudolite systems and the limitation of pseudolite receivers’ signal power ratio tolerance. -
表 1 衰减器挂载方案
组别 挂载方案 1 1号星(20 ${\text{dB} }$)、8号星(30 ${\text{ dB} }$) 2 2号星(20 ${\text{ dB} }$)、7号星(20 ${\text{ dB} }$) 3 2号星(20 ${\text{ dB} }$)、7号星(40 ${\text{ dB} }$) 4 3号星(30 ${\text{ dB} }$)、6号星(60 ${\text{ dB} }$) 
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