说明：  本文首先研究可4一DQPsK调制解调系统中调制部分的基本原理和各个模块的设计方案，重点研究成形滤波器和直接数字频率合成器 (DireetoigitalFrequeneySynihesis，简称DDS)，并针对各个关键模块算法进行matlab设计仿真，展示仿真结果。其次，研究调制解调系统解调部分的基本原理和各个模块的设计方案，重点研究差分解调，数字下变频和位同步算法，也针对其各个关键模块进行算法的Matlab设计仿真。然后用Matlab对整个系统进行理论仿真，得出结论。在此基础 上，采用超高速集成电路硬件描述语言(VeryHighspeedxntegatedeireuitHardware DescriptionLan即age，简称VHDL)在Altera公司 Quartusll7.0开发环境下设计并实现各个功能块，通过仿真来证明功能正确性。再次，用 Protel99SE进行印制电路板(Prinicircuitboard，简称PcB)设计，从原理图到封装，再到布局布线。焊接调试完毕后，将设计好的程序下载至FPGA主芯片。最后观察信号时域波形、星座图、眼图。本系统信源输入符号速率100kbPs，调制中频10MHz。测试结果验证系统的正确性，实现了从数字基带到中频的可4一DQPSK调制解调系统
(This study is the first 4 1 DQPsK modem modulation system, part of the basic principles and design of each module, focusing on shaping filter and a direct digital frequency synthesizer (DireetoigitalFrequeneySynihesis, referred to as DDS), and to address all the key modules algorithm matlab design simulation to show simulation results. Second, the study of modulation and demodulation system demodulation part of the basic principles and design of each module, focusing on differential demodulation, digital down conversion and bit synchronization algorithm, but also for its various key module of the Matlab algorithm design and simulation. Then use the Matlab simulation of the entire system theory, reach a conclusion. On this basis, , Using ultra-high speed integrated circuit hardware description language (VeryHighspeedxntegatedeireuitHardware DescriptionLan that age, referred to as VHDL) in the Altera Corporation Quartusll7.0 development environment to design and implement the variou)