低轨卫星信道模拟器设计与实现
发布时间：2019-01-02 07:32
【摘要】：低轨卫星移动通信系统运行轨道低、传输时延小和终端要求低等特点已使其成为卫星通信系统的一个主要发展方向。在低轨卫星移动通信系统中,信号会受多普勒效应、阴影效应、多径效应和传播噪声等因素的影响。所以,在低轨卫星移动通信系统的研发过程中,为了验证系统的可靠性,必须要了解低轨卫星信道对系统信号所产生的影响。在以往,人们大多采用外场试验的方法,租用实际卫星链路进行测试,但这种方法代价高昂且易受外界因素影响。所以,本课题设计了一种基于DSP的低轨卫星信道模拟器,该信道模拟器能够在实验室条件下实时模拟低轨卫星信道的传输特性,为低轨卫星移动通信系统的研制提供测试方法,具有重要的实际意义。 本文主要工作包括以下内容： (1)通过分析比较几种常用卫星信道模型,选择了IMS (Land Mobile Satellite)模型作为本低轨卫星信道模拟器的理论模型。 (2)针对LMS模型,提出了本低轨卫星信道模拟器的实现结构框图,并利用Simulink对其中的数字下变频系统进行了仿真,仿真结果验证了数字下变频系统中抽取滤波器的性能,为实际开发中数字下变频(DDC)芯片的参数设置提供了数据验证。 (3)提出了一种结合专用数字下变频芯片AD6620和DSP的低轨卫星信道模拟器实现方案。设计了一块中频处理子卡,再结合SEED-DEC6713开发板,,完成了本低轨卫星信道模拟器的硬件设计,并对各模块及模块间的具体电路设计进行了详细介绍。 (4)利用AD6620滤波器设计软件Fltrdsn得到了滤波器的最优抽取率组合,使用单片机AT89LV51完成了对AD6620的初始化设置,并给出了TMS320C6713与AD6620的接口程序及信号处理程序的设计。 (5)搭建了系统测试平台,利用信号发生器为系统提供模拟中频测试信号,然后通过CCS (Code Composer Studio)软件对测试结果进行观测与分析,测试结果表明,本低轨卫星信道模拟器能够模拟卫星移动通信信道的衰落和多普勒频移效应,达到了预期的设计目标。
[Abstract]:Low orbit satellite mobile communication system has become a main developing direction of satellite communication system due to its low orbit, low transmission delay and low terminal requirements. In Leo satellite mobile communication system, the signal is affected by Doppler effect, shadow effect, multipath effect and propagation noise. Therefore, in the research and development of Leo satellite mobile communication system, in order to verify the reliability of the system, it is necessary to understand the influence of Leo satellite channel on the system signal. In the past, people mostly used the method of field test to rent the actual satellite link for test, but this method is expensive and easy to be affected by external factors. Therefore, this paper designs a Leo satellite channel simulator based on DSP. The channel simulator can simulate the transmission characteristics of Leo satellite channel in real time under laboratory conditions, and provide a test method for the development of Leo satellite mobile communication system. It has important practical significance. The main work of this paper is as follows: (1) by analyzing and comparing several commonly used satellite channel models, IMS (Land Mobile Satellite) model is selected as the theoretical model of the Leo satellite channel simulator. (2) based on the LMS model, the implementation block diagram of the Leo satellite channel simulator is proposed, and the digital downconversion system is simulated by Simulink. The simulation results verify the performance of the decimation filter in the digital downconversion system. It provides the data verification for the parameter setting of the digital down conversion (DDC) chip in the actual development. (3) an implementation scheme of Leo satellite channel simulator based on AD6620 and DSP is proposed. In this paper, a sub-card of intermediate frequency processing is designed, combined with SEED-DEC6713 development board, the hardware design of the Leo satellite channel simulator is completed, and the specific circuit design of each module and module is introduced in detail. (4) the optimal decimation rate combination of the filter is obtained by using the AD6620 filter design software Fltrdsn, and the initialization setting of the AD6620 is completed by using the single-chip computer AT89LV51. The interface program between TMS320C6713 and AD6620 and the design of the signal processing program are given. (5) the system test platform is built, and the signal generator is used to provide the analog if test signal for the system. Then the test results are observed and analyzed by CCS (Code Composer Studio) software. The test results show that, This Leo satellite channel simulator can simulate the fading and Doppler frequency shift effect of satellite mobile communication channel and achieve the desired design goal.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN927.23
本文编号：2398195
[Abstract]:Low orbit satellite mobile communication system has become a main developing direction of satellite communication system due to its low orbit, low transmission delay and low terminal requirements. In Leo satellite mobile communication system, the signal is affected by Doppler effect, shadow effect, multipath effect and propagation noise. Therefore, in the research and development of Leo satellite mobile communication system, in order to verify the reliability of the system, it is necessary to understand the influence of Leo satellite channel on the system signal. In the past, people mostly used the method of field test to rent the actual satellite link for test, but this method is expensive and easy to be affected by external factors. Therefore, this paper designs a Leo satellite channel simulator based on DSP. The channel simulator can simulate the transmission characteristics of Leo satellite channel in real time under laboratory conditions, and provide a test method for the development of Leo satellite mobile communication system. It has important practical significance. The main work of this paper is as follows: (1) by analyzing and comparing several commonly used satellite channel models, IMS (Land Mobile Satellite) model is selected as the theoretical model of the Leo satellite channel simulator. (2) based on the LMS model, the implementation block diagram of the Leo satellite channel simulator is proposed, and the digital downconversion system is simulated by Simulink. The simulation results verify the performance of the decimation filter in the digital downconversion system. It provides the data verification for the parameter setting of the digital down conversion (DDC) chip in the actual development. (3) an implementation scheme of Leo satellite channel simulator based on AD6620 and DSP is proposed. In this paper, a sub-card of intermediate frequency processing is designed, combined with SEED-DEC6713 development board, the hardware design of the Leo satellite channel simulator is completed, and the specific circuit design of each module and module is introduced in detail. (4) the optimal decimation rate combination of the filter is obtained by using the AD6620 filter design software Fltrdsn, and the initialization setting of the AD6620 is completed by using the single-chip computer AT89LV51. The interface program between TMS320C6713 and AD6620 and the design of the signal processing program are given. (5) the system test platform is built, and the signal generator is used to provide the analog if test signal for the system. Then the test results are observed and analyzed by CCS (Code Composer Studio) software. The test results show that, This Leo satellite channel simulator can simulate the fading and Doppler frequency shift effect of satellite mobile communication channel and achieve the desired design goal.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN927.23
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