相位连续移频信号的数字化实现

Digital realization of frequency shift signal with continuous phase

分析了相位连续与不连续移频信号的频谱并比较了它们的带宽。相位连续的移频信号有较窄的带宽,抗干扰性能强。目前,在移频轨道电路中产生相位连续信号的方法主要有两种:直接调频法,频率转换法。前者相位连续但频率稳定性差;后者频率稳定性高但相位近似连续。为克服上述不足,本文提出了数字化直接调频法,其相位连续、频率可调、频稳性高。

In this paper, the frequency spectrum and the band width of the frequency shift signal with continuous and discontinuous phase are analyzed. The signal with continuous phase has narrower band width and higher interference-free capability. To generate the signal with continuous phase, two kinds of methods: the direct frequency modulation and the frequency conversion method are used in the frequency-shift track circuit. For the direct frequency modulation, the signal phase is continuous but the frequency stability is poor; for the latter method, the signal frequency stability is higher but the phase is just approximately continuous. To overcome their disadvantages, a new method called digital direct frequency modulation is put forward in this paper with advantages of continuous phase, adjustable frequency and high frequency stability.