【作者】 熊于菽；

【导师】 吴玉成；

【作者基本信息】 重庆大学 ， 电路与系统， 2007， 硕士

【摘要】 在数字通信系统中,全数字接收机已经得到了广泛的应用。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。最小高斯频移键控(GMSK)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,可有效降低邻道干扰,提高非线性功率放大器的效率,已在移动通信(如GSM系统)、航天测控等场合得到广泛应用。传统方法设计的GMSK调制解调器不能很好满足全数字化接收机可编程、多模式等需要。论文重点研究利用全数字化技术设计GMSK调制解调器,以便更广泛地使用GMSK调制解调技术。主要研究工作有:1.针对传统GMSK调制技术实现中存在的设计复杂、有相位累计误差等不足,基于相关文献思想,设计实现了一种改进的波形存储正交法GMSK调制信号生产方案。该方法不存在传统方法相位累加过程中的累计误差,而且无需滤波器,降低了数字化实现中的器件资源。仿真及FPGA实现结果表明,该方法计算量小、占用资源少,更容易实现高旁瓣抑制度的GMSK信号。2.研究了GMSK信号的数字化解调技术,针对突发通信系统的需要,对1比特差分解调和2bit差分解调技术进行研究,设计实现了1bit差分解调。计算机仿真和FPGA仿真测试表明,设计方案能正确实现GMSK的解调,误码性能较好。3.讨论了GMSK参数对系统性能影响。通过仿真对比,研究在收发端BT值的选取准则,对不同调制与解调技术的误码性能进行仿真研究和分析。4.完成设计方案的FPGA设计,进行FPGA仿真和在线下载验证,结果表明,设计方案可以正确实现GMSK的调制解调。论文的研究通过理论分析、方案对比、计算机仿真和关键技术FPGA验证的方式进行。研究表明,设计方案可行,经进一步细化和改造后可用于实际通信系统。更多还原

【Abstract】 In digital communication systems, all-digital receivers become more popular. It has become an important technology that realizes the modulator and demodulator of communication system in digitalization method. Minimum Gaussian frequency shift keying (GMSK) 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 communications system (such as GSM system) and others systems. The modulator and demodulator designed in traditional method can not meet the need of programmable, multi-mode for all digital receivers.The thesis focuses on the study on digitialization of GMSK modem. The main works involved as following:1. It is complex to design a GMSK moderm in traditional method, and the GMSK moderm has the shortage of accumulated phase error. Base on related literatures, an improved quadrature waveform storage GMSK modulation signal generation method was studied in the thesis. The method does not have the shortage of accumulated phase error in traditional method, needn’t filter and reduce the device resources significantly. Simulation results and FPGA realization results show that the method has the advantages of small computation, less resources and easy to realize high sidelobe suppressed GMSK signal.2. The demodaltion technologies in digitalization method is studied. To fit the need of burst communication systems, 1-bit and 2-bit differential demodulation method were studied. A 1-bit demodulator is designed and released. Simulation results and FPGA realization results show that scheme designed can demodulate GMSK signal effectively and archieve good BER performance.3. The effect of various GMSK parameters for system transmission performance is studied. Through simulation comparision, selection criteria for parameter BT and BER performance for various modu-demodu scheme were studied.4. The designed GMSK scheme has been realized in FPGA chips. Simulations and online verification results show that designed scheme work well. The study of the thesis is carried out by the method of theoretical analysis, scheme comparisons, simulations and FPGA verifications. Results shows that the scheme designed is feasible anc can be adopted in practice system after futher optimization.更多还原