The author also makes some Suggestions for frequency selection of digital carrier and parameters selection of spectrum shaping filter.

对数字载波的频率及频谱成形滤波器的特性参数的选择提出了建议。

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But to the CW pulse signal with changing carrier wave frequency, common filter cannot achieve narrowband filter, whereas broadband filter cannot reach the request of the signal-noise ratio.

可是，对于载波频率不断变化的CW脉冲信号，普通的滤波器难以实现窄带跟踪滤波，而宽带滤波又不能达到提高信噪比的要求。

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Because of the frequency lock loop traction PLL filter can be designed very narrow, with very good noise suppression performance, to meet the precise requirements of carrier phase tracking.

由于有锁频环的频率牵引，锁相环路滤波器可以设计得很窄，具有很好的抑噪性能，满足精确跟踪载波相位的要求。

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