基于双绞线的OFDM接收机物理层设计与实现

针对远距离、点对多点、多业务、大数据量的通信场景,提出了一种适合于双绞线传输的、基于OFDM的无中心无交换的收发信机系统方案.为了弥补远距离有线传输高频信号的衰减,该收发信机在发送端采用自适应调制和预均衡技术.在接收端采用自绕宽带阻抗匹配变压器,结合数模混合的可变增益（VGA）控制技术实现了AD前端信号幅度的调理.该VGA控制技术采用闭环控制,主要包括4个部分：前置放大电路、整流滤波电路、电压比较电路和能量检测电路（FPGA实现）.实验结果表明,在110.592 MHz的时钟频率下,信号调理的时间不到10 μs.在10 km传输距离下,能够满足15对用户同时在线.

PHY Design and Implementation of OFDM Receiver Based on Twisted-pair

For the long-range,multipoint,multi-service and large amount of data communication scenarios,this paper proposes a non-central OFDM transceiver system solution suitable for twisted pair without switching.The transceiver at the sending end utilizes adaptive modulation and pre-equalization techniques to compensate for long-distance cable attenuation of high frequency signals.Meanwhile,the receiver utilizes a self-winding broadband impedance matching transformer,combined with digital-analog variable gain amplifier（VGA） to realize the signal amplitude recuperation.The VGA uses closed loop control,comprised with preamplifier circuit,rectifier filter circuit,voltage comparing circuit and energy detection circuit（implemented in FPGA）.Experimental results show that it takes less than 10us to recuperate the signal with working clock frequency 110.592 MHz.The system can accordmodate 15 pairs of users on line at the same time in the distance of 10 kilometers.