SOQPSK-TG信号的简化状态解调器

针对部分响应成形偏移正交相移键控(SOQPSK-TG)信号的解调器复杂度较高的问题，在研究递归SOQPSK-TG信号的判决反馈简化解调器的基础上，对于非递归SOQPSK-TG信号提出了一种利用幸存路径的简化两状态解调器．该解调器在非递归SOQPSK-TG信号四状态网格的基础上，通过合理的状态合并，得到简化两状态网格；在接收机中采用该两状态网格作为状态转移网格对接收信号进行解调，在解调过程中由幸存路径法得到各支路的标准信号．仿真结果表明，在低信噪比区域，非递归SOQPSK-TG信号比递归SOQPSK-TG信号具有更优越的性能；与四状态解调算法相比，非递归SOQPSK-TG信号的简化两状态解调器有0.5～1.0dB的信噪比损失，但接收机具有较小的运算复杂度，有利于工程应用．

Reduced state demodulator for the SOQPSK-TG signal

To solve the problem of high complexity in the demodulator for a partial-response version of shaped-offset quadrature phase-shift keying(SOQPSK-TG), a simplified two-state demodulator for non-recursive SOQPSK-TG using the survivor path is proposed based on the decision feedback simplified demodulator of recursive SOQPSK-TG. First, a two-state trellis is deduced by proper state merging based on the four-state trellis of non-recursive SOQPSK-TG. Then, the simplified two-state trellis is used as the state transition trellis in the receiver to demodulate the received signal, and during the demodulation the hypothesized signal of each branch is obtained via the survivor path. Simulation results show that non-recursive SOQPSK-TG has a better performance than recursive SOQPSK-TG in the low SNR region, and the simplified two-state demodulator of non-recursive SOQPSK-TG has 0.5～1.0dB SNR degradation compared with the four-state demodulation algorithm; however the low computation complexity is beneficial to engineering application.