中文摘要：

电力线信道具有噪声强、衰减大的特点，信号通过信道后变化剧烈。OFDM电力线通信系统需要有效的增益控制策略。设计了一种两级调整结构的自动增益控制（AGC，autogaincontr01）方法，通过采用两级环路滤波能够有效应对信号突变，保证AGC的收敛速度和稳定性。同时加入能量检测单元，有效降低系统待机功耗。仿真结果表明，两级调整结构的AGC具有更好的收敛特性，能够满足电力线通信的要求。

英文摘要：

Due to the big impulse noise and strong attenuation of power line channel, the signals of OFDM power line communication systems are wide dynamic range and subject to large distortions, so an effective auto gain control method （AGC） is indispensable. A two-stage automatic gain control method is discussed. Two-stage AGC with two different loop filters has an upstanding performance for OFDM power line communication （PLC） systems, and has less time to achieve stable gain output. Moreover, in order to reduce the power dissipation of receivers, a power detection is set before AGC. Simulation results indicate the two-stage AGC has better performance and can satisfy the requirements of PLC systems.