深空测控通信中GMSK体制非相干解调算法研究

针对深空测控通信中GMSK体制非相干解调损失较大的难点，提出了一种改进的GMSK信号非相干维特比解调算法。通过分析相位状态网格图中相位转移规律，建立理论仿真模型。通过原理样机的研制和测试，实测数据表明：该算法具有解调损失低、实现复杂度适中的优点；相比于理论的最佳相干解调算法，在误码率1×10 -4 量级下，实测仅损失0.6 dB。目前该算法已应用于国内某深空测控通信系统GMSK体制基带设备中，并成功解调出欧空局Herschel–Planck卫星数据。

A Noncoherent Demodulation Algorithm of GMSK for Deep Space Missions

The existing various noncoherent demodulation algorithms of GMSK cause biggish loss for deep-space missions. A modified preponderant noncoherent demodulation algorithm with Viterbi decoding for GMSK signals is proposed in this paper. The simulation model is built by analyzing the phase transfer law in the phase state grid map. The performance test of principium equipment demonstrates that the modified algorithm has low loss of demodulation performance and medium complexity. And compared with the best coherent demodulation algorithm, it only causes a loss about 0.6 dB actually in the bit error rate of 1e-4. It has been applied to the GMSK baseband equipment in a certain deep-space TT&C system and has demodulated data from ESA Herschel–Planck satellite successfully.