基于星载数字滤波器的分段式预失真优化方法

卫星导航系统可以为全球各类用户提供高精度的导航、定位、授时服务，导航信号质量是影响系统服务性能的重要因素。导航载荷发射信道的非理想特性会引起导航信号的幅频特性和相频特性的变化，因此需要通过预失真手段对通道特性进行补偿。北斗三号卫星在数字段配置了预失真滤波器，但是由于受到星上资源有限以及宽带预失真算法精度不高等因素的制约，导航信号质量在预失真调整过程中很难快速收敛到指标范围内。本文设计了一种基于星载数字滤波器的分段式高精度预失真方法。在宽带滤波器已有的参数基础上，按权值和调整需求进行动态地、精细化地预失真补偿，使得关注的重点指标收敛精度更高。该方法经过了20颗卫星的在轨验证，是在轨导航信号质量优化的重要技术手段。

A piecewise pre-distortion optimization method based on spaceborne digital filter

The satellite navigation system can provide high-precision navigation, positioning and timing services for all kinds of users around the world. Navigation signal quality is an important factor affecting system service performance. The transmission channel of navigation load has non-ideal characteristics, which will cause the change of navigation signal amplitude frequency characteristic and phase frequency characteristic. Therefore, the channel characteristics need to be compensated by means of pre-distortion. BDS-3 satellite is equipped with a pre-distortion filter in the digital segment. However, due to the limited resources on-board and the low accuracy of broadband pre-distortion algorithm. It is difficult for the navigation signal quality to converge to the index range in the process of pre-distortion adjustment. A piecewise high-precision predistortion method based on spaceborne digital filter is designed. Based on the existing parameters of the wideband filter, the pred-istortion compensation is carried out dynamically and elaborately according to the weights and adjustment requirements, which makes the key indexes of attention converge with higher precision. This method has been verified by 20 satellites in orbit and is an important technical means for in-orbit navigation signal quality optimization.