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分析了火星科学实验室在进入、下降、着陆(EDL)过程中直接对地通信使用的MFSK信号及其信号检测算法,针对如何设置数据音频率间隔以及在不同多普勒动态下如何设置调制指数的问题,利用对比分析的方法,研究了MFSK调制指数、数据音频率间隔以及载波捕获/跟踪阶段多普勒频率变化率的大小对信息解算性能的影响。实验结果表明,数据音频率间隔对信息检测性能影响较小,建议将数据音频率间隔设为80 Hz;当载噪比低于17 d B-Hz时,调制指数应设为45°,否则应设为48°;载波捕获/跟踪阶段多普勒频率变化率的大小对信息检测性能影响较大,当多普勒频率变化率绝对值高于500 Hz/s时,信号检测门限会增加3 dB。
This paper analyzes the MFSK signal and its signal detection algorithm used by Mars Science Laboratory for direct communication to ground in the process of entering, descending and landing (EDL), and analyzes how to set the data audio frequency interval and how to set modulation index under different Doppler dynamics The effects of the MFSK modulation index, the data audio frequency interval and the Doppler frequency change rate on the performance of the information decoding are studied by using the comparative analysis method. The experimental results show that the data audio frequency interval has little effect on the performance of information detection. It is recommended to set the data audio frequency interval to 80 Hz. When the carrier to noise ratio is less than 17 d B-Hz, the modulation index should be set to 45 °, otherwise Is set as 48 °. The magnitude of Doppler frequency change rate in carrier acquisition / tracking stage greatly affects the information detection performance. When Doppler frequency change rate is higher than 500 Hz / s, the signal detection threshold will increase by 3 dB .