FH/DS软件无线电数传电台中π/4DQPSK调制解调技术的研究

【作者】 付士龙；

【导师】 刘镰斧； 查光明；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2007， 硕士

【摘要】 本课题是某FH/DS软件无线电数传电台中的一部分,本文在已实现的几种抗干扰模式的基础上,研究了π/4-DQPSK调制解调技术。π/4-DQPSK是一种线型数字调制技术,具有频谱利用率高,频谱特性好,抗干扰性强,保密性能好,可用非相干解调等突出特点。在移动通信,卫星通信中得到了广泛应用。本文首先介绍调制、解调的基本原理和各个组成模块的设计实现,如:成形滤波器,中频解扩、解调,位同步。其次完成了扩频调制、解扩、解调算法的Matlab仿真设计,在此基础上,采用VHDL硬件描述语言在Xilinx公司的ISE6.1开发环境下设计实现各种抗干扰模式的调制解扩解调及相应的模块,通过了时序仿真,实现正确解扩解调。该方案的解扩解调算法采用中频带通采样,数字匹配滤波器解扩,延时差分解调技术直接在中频上完成了数字信号处理,相对于经典做法节省了下变频,伪码同步捕获和载波提取电路。该方案相对实现较为简单,具有一定的新意和实用价值。最后,该方案在该项目通用的软件无线电硬件平台上实现了预期的功能。测试结果验证了程序的正确性,表明该方案是正确的,可行的。更多还原

【Abstract】 The aim of this thesis is to implement all digital modem ofπ/4 offset differentially encoded quadrature phase shift keying(π/4-DQPSK), based on some modes, which belongs to a part of the FH/DS software radio data radio.π/4-DQPSK modulation is a linear technology, which possesses features of high spectrum utilization ratio, better spectrum specification, strong anti-jamming ability and good security. The modem method has been employed in mobile communication system and satellite communication system.The paper firstly introduces the rationale of a FPGA-Basedπ/4-DQPSK modem and design & realization of each module, such as pulse shaping filter, despreading and demodulation on IF, bit synchronization. Secondly, author has done algorithm simulation with Matlab. Based on this, under the ISE6.1 of Xilinx company, Very High Speed Integrated Circuit Hardware Description Language (VHDL) has been adopted for designing and implementing every module. Via observing timing simulation, programme can implement right modem, demodulation. This scheme adopts intermediate frequency sampling, digital matched filtering, delay differential demodulation techniques and so on. It directly processes the digital signals on intermediate frequency without down-conversion, and doesn’t need pseudo random codes synchronization and carrier wave extraction circuits, compared with classic method. This scheme is characterized by its simplicity, easy implementation, novel ideas and practical value. Thirdly, the scheme has been implemented on the universal soft radio platform to meet the scheduled object. Testing result validates that the program is right, and demonstrates that this scheme is correct and feasible.更多还原