GPSBIIF-1卫星L1频点QPSK VS CASM信号质量评估

QPSK VS CASM Signals Quality Assessment on GPSBIIF-1 Satellite L1

为了评估GPS L1频点信号体制转换前后的空间信号质量,基于高增益天线接收系统采集数据,对相干自适应副载波调制(CASM)调制和QPSK调制信号质量进行对比分析。首先,简要介绍CASM调制模型,利用波形匹配技术求解L1频点授权信号伪码序列。其次,基于星座图分布和极大似然估计分别解决出QPSK和CASM调制信号分量功率分配难题。最后定量地利用相关特性参数中的S曲线过零点偏差(SCB)和相关损失(CL)对比分析L1频点信号体制转换前后各信号分量空间信号质量。该文结果可为不同信号体制下空间信号质量评估对比提供参考。

In order to evaluate the spatial signal quality before and after the conversion of the GPS L1 frequency point signal system,this paper compares the quality of the coherent adaptive subcarrier modulation( CASM) modulation and the QPSK modulation based on the data collected by the high-gain antenna receiving system. Firstly,the CASM modulation model is briefly introduced,and the waveform matching technique is used to solve the pseudo-code sequence of the L1 frequency authorized signal. Secondly,the power allocation problems of QPSK and CASM modulated signal components are solved respectively based on the constellation distribution and the maximum likelihood estimation. Finally,the S-curve bias( SCB) and the correlation loss( CL) in the relevant characteristic parameters are used to quantitatively analyze the spatial signal quality of each signal component before and after the conversion of the L1 signal system. The results can provide references for the comparison of the spatial signal quality assessment under the different signal systems.