基于FPGA的LEO卫星通信大频偏时钟 恢复算法设计
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上海大学特种光纤与光接入网重点实验室 上海 200444

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TN927

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Design of clock recovery algorithm for large frequency offset in LEO satellite communication based on FPGA
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Key Laboratory of Specialty Fiber and Optics Access Networks, Shanghai University,Shanghai 200444, China

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    摘要:

    在卫星高速数传通信系统中,多普勒效应等因素会导致收发符号定时偏差加大,采用Gardner时钟恢复算法可以有效地消除其影响。然而现有时钟恢复算法实现结构存在着采样速率和实现复杂度较高的问题,由于实际系统中采样率和硬件资源有限,使其难以满足更高速率以及更高定时偏差容忍度的需求。基于Gardner时钟恢复算法,提出了一种新的并行实现结构,通过引入增删状态机、样值调整模块以及符号抽取模块使其能够在两倍符号率采样时实现快速符号定时计算。仿真及FPGA板级测试表明,该结构适应QPSK/8PSK/16APSK多种调制格式,能够容忍高达±400×10-6的定时频率偏差,且长期测试误码率稳定。另外,在实现625 MBaud符号率的实时接收机系统时,所提出的并行实现结构相对传统结构节省了约37%的LUT资源以及一半以上的Register和DSP资源,在资源受限的实时通信系统中具有很大的应用价值。

    Abstract:

    In a high-speed satellite data transmission system, factors such as the Doppler effect will cause symbol timing offset between transmitter and receiver, it can be effectively corrected by the Gardner clock recovery algorithm. However, the existing implemental structure of clock recovery algorithm has disadvantages of high sampling rate and complexity, it is difficult to meet the requirements of higher symbol rate and timing offset tolerance because of limited sampling rate and hardware resources in the real-time system. Thus, this paper proposes a new parallel structure based on the Gardner clock recovery algorithm. By introducing add/delete state machine, sample adjusts module, and symbol extract module, it can realize fast symbol timing estimation when sampling at twice the symbol rate. Simulation and FPGA board-level tests show that this structure is suitable for multiple modulation formats of QPSK/8PSK/16APSK. It can tolerate timing frequency offset of up to ±400×10-6, and has a stable bit error rate in long-term tests. In addition, when implementing a real-time receiver system with 625 MBaud symbol rate, the parallel structure proposed in this paper saves about 37% of LUT resources and more than half of the Register and DSP resources compared with the traditional structure. It is practical and has great value in a real-time communication system with limited resources.

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罗艳飞,冯智波,谭家乐,朱彦铭,张俊杰.基于FPGA的LEO卫星通信大频偏时钟 恢复算法设计[J].电子测量技术,2023,46(21):43-48

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  • 在线发布日期: 2024-03-04
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