The results show that ( 1 ) the " prediction & cancellation " method can successfully smooth the reverberation and sharpen edges of the echo , so may detect echoes which power are great than the reverberation background by odb in one channel , ( 2 ) the scaled probabilities method can effectually separate a echo which power is great than the background by 6db , while the reverberation is cancelled dr astically 果。计算结果表明， “预测一抵消”算法对混响有平滑作用，对回波则有突出信号边缘的作用，单通道情况下的最小可检测信号干扰背景功率比约为odb 。概率净化算法在信号干扰背景功率比大于6db的情况下能有效分离回波、抑制混响。
And pays emphasis on analyzing the system structure and system flow , the core techniques , the channel characteristic and parameters of dvb - t system . the system adopts some core techniques such as cofdm , a lot of tps ( transmission parameter signalling ) insert and guard interval , and so on . so it can withstand high - level ( up to odb ) , long delay static and dynamic multipath distortion 论文首先描述了数字电视地面广播的需求条件，技术难点和目前存在的问题，并重点分析了dvb - t系统结构流程，核心技术及系统信道特性和参数，该系统采用了cofdm (编码正交频分多路复用) ，大量导频信号插入和保护间隔技术等核心技术，使之能抵抗高电平( 0db ) ，长延时的静态和动态多径失真，有利于数字和模拟电视的混合传输，它的多载波调制模式功能和性能在移动和便携接收、同频网等方面具有独特的优势。
A patch antenna with etched holes on the ground plane is also studied . the performance of the antenna at the resonant frequency is analyzed by using the fdtd method together with the pml boundary treatment . the results show that the surface waves are suppressed greatly , the bandwidth is improved and a 1 odb reduction on the sidelobe level is achieved at the 110 and 260 directions in the e plane 全面地研究了地面腐蚀周期圆孔结构的电磁晶体贴片天线在基波频率处的性能，用fdtd方法并结合pml边界处理技术对该天线所取得的研究结果显示，本文设计的地面腐蚀型电磁晶体结构抑制了贴片天线中的表面波，增加了天线的带宽，并有效地削弱了旁瓣，使天线的e面方向图上110和260方向的两个旁瓣被削弱了10db 。
