【作者】 熊伟；

【导师】 江桦；

【作者基本信息】 解放军信息工程大学 ， 电路与系统， 2009， 硕士

【摘要】 复合调制信号是VHF/UHF频段中一类重要信号,在许多领域有着重要应用。本文从电磁频谱监测及信号侦察的角度,研究了复合调制信号的识别、参数估计、VHF/UHF频段信号搜索检测等问题,并在一个通用信号处理平台上完成了相关算法的系统实现。主要内容如下:1、针对目前复合调制信号概念存在的模糊性,归纳总结了复合调制信号三种基本类型,仿真分析了各自的功率谱特征以及它们复合方式的异同。2、针对复合调制信号与非复合调制信号大类的区分,本文根据这两大类信号在瞬时值功率谱上的差异,提出了一个反映副载波信号个数的特征矢量参数,较好的实现了它们的分类,且该参数计算简单,分类性能良好。根据复合AM与复合FM调制信号在瞬时幅度统计特征上的不同,本文研究采用瞬时幅度归一化方差实现了这两类信号的区分。对于复合调制信号类内的识别问题,本文改进了信号的非线性变换功率谱特征及信号直方图统计特征提取方法,得到复合调制信号中的副载波信号的识别特征,从而实现了各种复合调制信号类内的区分。在对复合调制信号各种特征分析提取的基础上,研究了基于判决树的复合调制信号分类算法,实现了复合调制信号的在线识别。3、根据实际复合调制信号功率谱的特点,研究改进了常规信号载波频率估计算法,实现了复合调制信号载波频率的精确估计。根据循环平稳理论,分析总结了基于离散谱线检测的副载波频率精确估计方法。针对码元速率的估计,本文改进了包络平方与小波变换提取码元速率谱线的方法,从而提出基于希尔伯特-非线性变换和基于希尔伯特-小波变换的两种复合调制信号码元速率估计方法,并进行了对比分析,总体上后者性能较好。4、研究了现有信号搜索检测的一般方法,针对搜索过程中的搜索门限设置受信道色噪声严重干扰等关键问题,提出了一种基于信道色噪声抑制的全景频谱搜索方法,较好地提高了VHF/UHF频段信号搜索的性能。5、根据实际情况,课题完成实现了复合调制信号监测系统各功能模块,通过初步测试表明系统总体性能良好,实用性较强。更多还原

【Abstract】 The hybrid modulation signal of VHF/UHF channel is used in many fields. It is also a kind of importent signal for electromagnetic spectrum monitoring. The paper mainly researchs automatic recognition and parameter estimation of hybrid modulation signal, signal reconnaissance and detection in VHF/UHF channel. The studied relevant algorithm has also been realized on a general signal processing platform. The main work can be summarized as follows:1. With obscure definition of hybrid modulation signal in reality, the paper sums up three kinds of hybrid modulation signals, disscusses their characteristics of the spectrum and compares their difference of hybrid type.2. For the recognition of hybrid modulation and non-hybrid modulation signal, the paper studies the spectrum difference of instantaneous frequence and amplitude. One new characteristic which shows the number of subcarrier signal is proposed to acheive the classification of hybrid modulation and non-hybrid modulation signal. For the classification of hybrid AM and hybrid FM, the paper discusses the unitary variance of instantaneous amplitude of signals. For the recognition between the hybrid modulation signals, the paper improves the algorithm of nonlinear transformed spetctrum feature and statistic histogram. The improved algorithm extracts the subcarrier signal feature and realizes the classification of hybrid modulation signal. Finally, a classification scheme is designed to fit for the task which is given using the classical decision tree structure, and it gets an optimal classifying result.3. A carrier estimation algorithm of non-hybrid modulation signal is improved for practical hybrid signal, by suming up the algorithm of nonlinear transformed spetctrum feature for estimation of subcarrier frequence. For the symbol rate estimation for hybrid modulation signal, two methods are proposed in the paper; one method is based on Hilbert-nonlinear transform, the other is based on Hilbert-wavalet transform. The result shows the performance of method based on Hilbert-wavalet transform is better efficient4. The paper studies the normal method of signal reconnaissance. With the problem of level seting from channel color noise in signal reconnaissance, a new signal reconnaissance method based on channel color noise suppressing is proposed in the paper. The algorithm improves the pragmatic performance of signal reconnaissance in VHF/UHF channel.5. .A system for monitoring hybrid modulation signal is implemented, and its functions are introduced in the last chapter. The experiment shows the system is pragmatic and efficient.更多还原