Due to the complexity of the information channel ,its spectrum utilization ratio is usually low in the power-line carrier communication system .In order to increase the ratio ,the OFDM multi-carrier technology and high-order modulated code-pattern systems such as the Nyquist system and the FTN system are commonly applied .The spec-trum components of the clock information will reduce or vanish because of the spectrum compression , which will make the traditional clock recovery technology lose its efficacy .The new technology presented in this essay will solve the problem .Even if the roll-off factor of the pulse-shaping filter of the transmitting terminal approaches zero or al-most reaches zero ,the new technology can still stably recover the reception the clock in the code element .Relevant simulations show that the improved Gardner algorithm can be applied in both the traditional single -carrier system and the spectrum-compressed system .%电力线载波通信（ PLC）系统中，由于信道的复杂性，信道频谱利用率一般很低。为了提高频谱利用率，目前常见的方法是通过正交频分复用（ OFDM）的多载波技术与高阶调制码型，如南奎斯特系统、超南奎斯特（ Fas-ter-than-Nyquist，FTN）系统[1-2]。由于频谱被压缩，时钟信息在频谱上的分量减少或是消失，导致传统的时钟恢复技术失败。由此提出了时钟恢复新技术，可以解决该问题。即使发射端的脉冲形成滤波器滚降系数趋近或逼近零时，也可以稳定地恢复接收码元中的时钟。通过仿真得出，改进的Gardner算法不仅可以用到传统的单载波系统，也可以用到这种频谱压缩后的系统。
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