说明：  介绍了一种可在较短时间内检测到数字电视国标系统工作模式的方法。该方法利用帧头PN序列和PN序列扩展保护部 分的相关特性、循环特性以及0FDM信号部分的周期特性进行判决，可达到很好的检测效果，该方法同时可加入跟踪模块对系统 工作模式的突然改变作出反应。还介绍了两种可以在硬件资源和性能上进行折中的检测方法
(Describes a method can be detected in a relatively short period of time to a digital television GB system working mode. The method utilizes the correlation characteristics of the the header PN sequence and the PN sequence extension protective portion, the cycle characteristics of the cycle the characteristics and 0FDM signal portion judgment can achieve good detection results, the method at the same time tracking module may be added to the system working mode sudden change the response. Also describes two hardware resources and performance compromise detection method)