本文提出了一种基于分数阶Fourier变换的chirp-rate调制(CRM)非相干解调方法,并导出了其解调器的输出峰值;其次,从多普勒频移和码同步误差两个方面,将本文方法与匹配滤波相干解调方法进行了对比分析,得到了相应的对解调性能影响的解析表达,可以发现chirp-rate调制具有很强的抗多普勒频移能力,但是对码同步误差较为敏感.最后,通过仿真分析,验证了上述理论推导的正确性,并对比了本文方法和匹配滤波相干解调的误码性能.由于本文方法是一种非相干解调,所以相较匹配滤波相干解调差了约3dB.
A noncoherent demodulation method for chirp-rate modulation is proposed based on the fractional Fourier transform, and the peak output of the demodulator is derived. Thereafter, this method is compared with coherent demodulation with matched filter from two aspects of Doppler shift and bit synchronization. And the analytical expressions of influence caused by the two factors are obtained,from which we can see that chirp-rate modulation has strong robustness on Doppler shift but sensitivity of bit synchronization. Finally,the simulations are made to prove the above-mentioned theories,as well as to analyze Bit Error Rate (BER). The performance of this proposed method is worse than coherent demodulation with matched filter for the former' s noncoherent mode,but the difference in BER is 3 dB.