一种组合的8PSK差分前向频率估计

A Combined Differential Feed-forward Estimator for 8PSK

考察2种差分前向估计器（DFE）在8PSK系统载波恢复中的性能：基于8thPower算法的DFE将噪声放大了18dB，恶化了估计性能，但该算法稳健性好；基于模π／4算法的DFE在复高斯噪声的情况下求模运算引入了错误相位点，若能纠正这些错误相位点，则该算法估计精度高。综合2种算法的优点，提出一种组合式的频率估计方案。仿真结果表明，该方案有效纠正了模π／4算法求模运算引入的错误相位点，估计精度高，估计结果稳定可靠。

This paper analyzes the performance of two types of Differential Feed-forward Estimators （DFE） in carrier recovery in 8PSK systems. The 8th power algorithm-based DFE amplifies the noise by about 18 dB and deteriorates the estimator＇s performance. However, it is still a robust algorithm. The med π/4 algorithm-based DFE induces wrong phase values in modulo operation under the impact of Gaussian complex noise. As long as the phase values are corrected, the estimated result has a high accuracy. A combined frequency estimating scheme that integrates the merits of both is proposed. Simulation results show this scheme effectively corrects the wrong phase values in the med π/4 operation, and the estimation is accurate and stable.