基于FFT的国标数字电视系统帧头模式捕获方法

Acquisition method of frame head PN mode in DTMB system based on FFT

在分析国标数字电视传输系统帧头信号特征的基础上,提出一种基于FFT(Fast Fourier Transforms)的帧头PN(Pseudorandom Noise)模式捕获方法.该方法基于每种帧头的特点及硬件实现的难易程度,选取3种特定的本地基础序列在各自通道中与接收到的信号帧进行基于FFT的相关运算,并通过比较每通道的相关峰值与相应的判决门限来判定本通道是否捕获成功,从而选择捕获成功的通道所对应的帧头模式作为最终识别出的帧头模式.与应用时域相关运算的捕获识别方法相比,提出的方法能够降低计算复杂度,提高捕获速度.仿真结果显示,该方法能够捕获识别出各种帧头PN模式,验证了方法的可行性.

An acquisition method of frame head pseudorandom noise（PN） mode in digital terrestrial television multimedia broadcast（DTMB） system based on fast fourier transforms（FFT） was proposed according as the analysis of the character of frame head PN in Chinese national standard on DTMB. In this method, firstly, three kinds of local sequence are chosen based on the frame head＇s character and the difficulty in hardware design to correlate with signal frame received, in which FFT correlation method was used. Then, correlation peak of each channel was compared with the relevant threshold to judge whether the acquisition succeed in a certain channel or not. At last, frame head mode corresponding to the channel which has acquired PN successfully was chosen as the final frame head PN mode for the output. Compared with the acquisition method based on time-domain correlation, the proposed method needs less computation overhead and acquisition time. Simulation results show that the method can acquire and identify all kinds of frame head PN mode accurately and the feasibility of the method is validated.