【作者】 曹博；

【导师】 祝忠明；

【作者基本信息】 成都理工大学 ， 电路与系统， 2010， 硕士

【摘要】 软件无线电在无线通信领域被称为是自模拟通信过渡到数字通信之后的又一次革命,在军用和民用方面都有着广泛的应用。它是一种新的无线通信技术,基于通用的可编程硬件平台,把尽可能多的通信功能用软件实现,从而使系统的改进和升级都非常方便,容易实现不同通信系统之间的兼容。软件无线电的基本思想是构造一个具有开放性、标准化、模块化的通用硬件平台,从而使软件无线电中的调制方式产生多模式化。而多模式调制的存在,就要有自动的多模式调制的识别方法。所以,多模式调制方式的自动识别是软件无线电中必须具备的功能。如何将多模式调制的识别方法与软件无线电的解调方法相结合,同时实现信号的接收和解调,是实现软件无线电的关键技术之一,具有重要的应用前景。而在数字通信系统中,全数字接收机已经得到了广泛的应用。如何利用数字化方法设计通信系统中的调制解调技术是实际应用中的一项重要技术。GMSK最小高斯频移键控是一种典型的连续相位调制方式,具有包络恒定、频谱紧凑、抗干扰能力强等特点,在移动通信等场合得到了广泛应用。在GMSK调制解调的实现中采用了FPGA可编程逻辑器件,不仅克服了模拟系统灵活性不好的缺点,而且易于系统的修改和升级。针对上述情况,论文的主要研究工作有:1、介绍了软件无线电的三种结构形式,针对目前的设计条件,指出宽带中频带通采样软件无线电结构是目前较为理想的结构形式。2、对调制模式识别中基本特征参数频率、包络以及相位的提取方法进行了分析,并在此基础上对三种调制信号分类方法分别进行了讨论。在信道条件较好的情况下,提出利用参量直方图的方法对三种基本特征参数分别进行统计,根据峰值的数目从而可以来区分ASK、PSK和FSK信号。当信道条件一般时,文中以决策论为依据,使用4个特征参数实现了二进制和四进制ASK、FSK、PSK的分类。3、采用高阶统计量的方式对低信噪比条件下的调制信号进行识别,利用计算出的几个高阶累积量,提取特征参数,成功地实现了低信噪比条件下ASK、PSK和FSK的二制和四进制信号的分类。4、最后在Mat1ab中进行对软件无线电中的GMSK调制与解调的仿真,并且在FPGA上实现其调制与解调。更多还原

【Abstract】 Software radio in the wireless communications known as the transition from analog communication to digital commucation again after revolution in military and civilian aspects have a wide range of application.It is a new wireless communication technology.Programmable hardware based on a common platform,the communication function as much as possible with software,making system improvements and upgrades are very convenient and easy to achieve compatibility between different communication systems.The basic idea of Software Radio is to construct a general hardware platformwith openness,standardization and modularization.The generalization of SR must bringthe multi-modularization,so the automatic multi-mode modulation recognition methodcomes into necessity to ensure correct demodulation.As a result,the automaticmodulation recognition is one of the necessary functions.How to make the method ofautomatic modulation recognition adaptive to thedemodulation method and realize theautomatic reception and demodulation is one of the key technologies and must have a wide application.In digital communication systems,all-digital receivers become more popular.It hasbecome an important technology that realizes the modulator and demodulator of communication system in digitalization method.GMSK Minimum Gaussian frequency shiftkeying is a typical continuous phase modulation method,which has the characteristics of constant envelope,compact spectrum,and anti-jamming performance.GMSK can effectively reduce inter-channel interference,improve the efficiency of non-linear power amplifier,and has been widely used in mobile system and others systems.In the GMSK modem used in the FPGA implementation of programmable logic devices,analog system flexibility not only to overcome the shortcomings of bad,and easy system modifications and upgrades.In allusion to the status mentioned above,the contents finished in the dissertationare listed as follows:1 The three Software Radio architectures were introduced and the wideband and band-passsample architecture was proved as the practical one now in the present design condition. 2 The extraction method of character parameter including envelope,frequency and phase was analyzed and three classification method of digital modulationwere also discussed.When channel condition is good,the parameter histogramdistribution method was introduced to make a statistics of the three basic characterparameters.According to the peak number,the 2ASK,4ASK,2PSK,4PSK,2FSK and 4FSK can be classified well.In the channel condition that is not so good,the decisiontheory method was adopted to extract four character parameters so that the classificationof 2ASK,4ASK,2PSK,4PSK,2FSK and 4FSK was realized.3 The recognition of modulation signals under the low SNR condition is alwaysthe important research content of signal recognition.In the dissertation,the high ordercumulants method was adopted to realize successfully the classification of 2ASK,4ASK,2PSK,4PSK,2FSK and 4FSK by extracting four character parameters based onseveral high order cumulants calculated.4 Finally Matlab carried out on software radio GMSK modulation and demodulation of the simulation,and FPGA to achieve the modulation and demodulation.更多还原