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1.引言众所周知,用设计适当的锁相环或者用反馈频率解调器解调淹没在噪声中的调频信号,都可以扩展调频噪声门限。最近在文献[5]中提出了锁频环也能扩展门限。本文证明锁相环和锁频环的定义方程只是调频反馈定义方程的一种极限形式。因此,只用一种基本装置(调频反馈)就能扩展门限,而不必用三种不同的装置。而由这种装置可以引出其它两种,即锁相环和锁频环。特别是证明了,当调频反馈内部中频滤波器带宽减小到零时,调频反馈与锁相环有相同的定义方程,相反,当带宽无限增加时,调频反馈和
1. Introduction As we all know, with the proper design of phase-locked loop or feedback frequency demodulator demodulated submerged in the noise of the FM signal, you can expand the FM noise threshold. Recently, it was proposed in [5] that the frequency-locked loop can also extend the threshold. This paper proves that the definition equation of phase-locked loop and frequency-locked loop is only a limit form of FM feedback definition equation. Therefore, the threshold can be expanded with only one basic device (FM feedback) without having to use three different devices. By this device can lead to the other two, that phase-locked loop and frequency-locked loop. In particular, it is proved that the FM feedback has the same definition equation as the PLL when the bandwidth of the IF filter is reduced to zero. On the contrary, when the bandwidth is infinitely increased, the FM feedback