【摘要】 倒车雷达是汽车泊车或者倒车时的安全辅助装置，能以声音或者更为直观的显示告知驾驶员周围障碍物的情况，解除了驾驶员泊车、倒车和起动车辆时前后左右探视所引起的困扰，并帮助驾驶员扫除了视野死角和视线模糊的缺陷，提高驾驶的安全性。本设计利用ATMEL公司的AT89C51单片机、超声波传感器测距实现超声波倒车雷达。利用LED和发光二极管表示传感器探测范围内是否有障碍物，当在探测范围内有障碍物时，发光管以一定频率闪烁，闪烁的频率以距离定，距离越近频率越高。同时蜂鸣器提示报警，探测并指明障碍

The performance of a visible light communication system is greatly affected by LED layout setting. Received power and SNR can be increased or decreased by changing LED placement. However, there is trade-off between received power and SNR. This makes

The performance of a visible light communication system is greatly affected by LED layout setting. Received power and SNR can be increased or decreased by changing LED placement. However, there is trade-off between received power and SNR. This makes

将OFDM技术运用在可见光通信的研究，并且把OFDM的高峰均比这一缺点进行了建设性的运用。-In particular, the use of OFDM (orthogonal frequency division multiplexing) for intensity modulation is investigated. The high peak-to-average ratio (PAR) in OFDM is usually considered a disadvant