An improved adaptive image watermarking algorithm based on block dct and arnold shuffling is proposed : with shuffling techniques in image watermarking , you can not only prevent illegal users from riddling the content of the images , but also disperse the distributing of error bits in order to enhance the robustness of watermarking 提出了一种改进的基于分块dct ( discreteconsinetransform )变换和arnold变换的自适应图像水印算法:本文将信息置乱技术用于图像水印中,一方面可以使非法使用者无法破译图像的内容,另一方面可以尽可能的分散错误比特的分布,从而提高数字水印的鲁棒性。
By theory and practice simulation , the several types of constant envelope modulation techniques are analyzed and compared , including theirs modulation principle , phase path , the modulated wave envelope , power spectrums , error bit rate and the influence of its power spectrums of the band - limited and non - linear , etc . especially we have researched the ijf - oqpsk modulation technique , and the performance of its inter - symbol interference and time jitter free , and its strongly resisting of spectral spreading 结合理论和实验仿真结果,分析讨论了卫星通信中的各种恒包络调制技术,对它们的调制原理,相位路径,已调波包络,功率谱密度,误码性能,以及带限非线性信道对其功率谱的影响等方面都作了研究和比较。特别研究了ijf ? oqpsk在消除码间干扰和定时抖动方面的性能及其优良的旁瓣特性和抑制频谱扩展特性。
Space time coding was proposed by combining transmit diversity and coding technology to improve the system performance , such as error bit rate , data rate , and system capacity . in particular , space - time block coding ( stbc ) schemes , proposed originally by alamouti were adopted by the 3g standardization committees as one key technique in 3g wireless systems 将发送分集与编码调制技术相结合,进一步产生了空时编码技术,由于空时编码技术具有优异的抗衰落性能,并且能通过发送分集和接收分集提供高速率、高质量的数据传输,因此它已经成为第三代移动通信技术的重要组成部分,并将继续在下一代移动通信技术的发展中发挥重要作用。
The communication system ' s performance is briefly analyzed by channel capacity , which is a function of bit error rate ( ber ) . the decision rule is based on the most likelihood method . for reproducing the original binary signals more correctly , time scale transformation method and the approach of ensemble average probability of error bits are introduced 通过理论分析和仿真实验,本文研究了这个非线性数字通信系统性能,给出了误码率和信道容量公式,提出了系统参数调节方法,采用最大似然法设计了适合这个系统输出的判决规则。