基于判决反馈的VDES解调系统设计与FPGA实现

doi:10.12382/bgxb.2022.0471

摘要/Abstract

摘要：

甚高频数据交换系统(Very high frequency Data Exchange System,VDES)作为新一代船舶通信系统,具有广阔的应用前景。由于卫星相对船舶的高速运动,VDES中上行应用特定消息(Application-specific Message,ASM)链路会产生较大的多普勒频移,在接收端仅依靠已知训练序列估计的频偏等信道参数无法满足正确解调的性能要求。为此提出一种基于判决反馈的解调方法,通过分段解调,缩短每次解调的数据长度,提高解调时对频偏的容忍度,并利用每段解调的结果作为下一段未解调数据的导频,估计出当前数据中的信道参数。仿真结果表明,所提算法相较于无反馈相干解调算法性能大大提升。在上述研究的基础上,在可编程逻辑器件上实现了对ASM无导频上行链路的正确解调。

关键词: 信号处理, 甚高频数据交换系统, 判决反馈, 可编程逻辑器件

Abstract:

VHF data exchange system (VDES) has broad application prospect as a new generation of ship communication system. Due to the high-speed motion of satellite, a large Doppler frequency shift is superimposed on the ASM uplink in VDES, and the channel parameters estimated only by training sequence in receiving end cannot meet the requirements of demodulation. Therefore, a VDES demodulation system based on decision feedback algorithm is proposed. The received data is split into small segments, which reduces the influence of frequency offset. The demodulated result of each segment is used as pilot to estimate the channel parameters in current data segment. Simulated results show that the performance of the proposed algorithm is superior to that of the coherent demodulation algorithm without feedback. On the basis of the above research, the correct demodulation of ASM uplink without pilots is implemented on the filed programmable gate array(FPGA).

Key words: signal processing, VHF data exchange system, decision feedback, filed programmable gate array

中图分类号:

TG510

孙定柱, 冯熳, 狄芳, 陈鹏. 基于判决反馈的VDES解调系统设计与FPGA实现[J]. 兵工学报, 2024, 45(1): 312-318.

SUN Dingzhu, FENG Man, DI Fang, CHEN Peng. Design and FPGA Implementation of VDES Demodulation System Based on Decision Feedback Algorithm[J]. Acta Armamentarii, 2024, 45(1): 312-318.

图/表 9

图1 ASM-SAT链路帧结构示意图

Fig.1 Schematic diagram of ASM-SAT link frame structure

图2 判决反馈算法流程图

Fig.2 Flow chart ofdecision feedback algorithm

图3 频偏估计模块实现结构图

Fig.3 Structure diagram offrequency estimation module

图4 频偏估计算法性能图

Fig.4 Performance diagram of frequency estimation algorithm

图5 分段长度仿真性能图

Fig.5 Simulation performance diagram of segment length

图6 判决反馈算法性能图

Fig.6 Performance diagram of decision feedback algorithm

图7 判决反馈算法FPGA仿真图

Fig.7 Simulation diagram of FPGA implementation

表1 实际测试性能

Table 1 Actual test performance

信号功率/dBm	帧正确率/%
-80	100
-90	100
-100	100
-110	99.8
-120	77.7

图8 解调算法FPGA实现资源占用率

Fig.8 Resource occupancy rate of FPGA implementation

参考文献 21

[1]	巩海方. 谈甚高频数字交换系统(VDES)[J]. 中国海事, 2016(3):53-55.
	GONG H F. Talking about VDES[J]. China Maritime Safety, 2016(3):53-55. (in Chinese)
[2]	赵玉民, 王黎莉, 艾云飞, 等. 天地一体VDES发展现状及应用展望[J]. 卫星应用, 2022(2):41-45.
	ZHAO Y M, WANG L L, AI Y F, et al. Development status and application prospect of VDES[J]. Satellite Communication, 2022(2):41-45. (in Chinese)
[3]	郝永宸, 李洪星, 方莉, 等. 甚高频数据交换系统(VDES)中的帧同步方案[C]// 2016智能电网发展研讨会论文集. 北京: 中国电力科学研究院, 2016:655-659.
	HAO Y C, LI H X, FANG L, et al. Frame synchronization scheme in very high frequency data exchange system (VDES)[C]// Proceedings of 2016 Smart Grid Development Seminar. Beijing, China: China Electric Power Reserch Institute, 2016:655-659. (in Chinese)
[4]	MA S X, SHI K, MENG X, et al. Frequency offset estimation algorithm of VDES signals based on cross-correlation[C]// Proceedings of the 2018 IEEE 4th International Conference on Computer and Communications. Chengdu, China: China Institute of Communications, 2018:1234-1238. doi: 10.1109/CompComm.2018.8780774.
[5]	FITZ M P. Further results in the fast estimation of a signal frequency[J]. IEEE Transactions of Commun, 1994, 42(2):862-864. doi: 10.1109/TCOMM.1994.580190 URL
[6]	范家辉, 王建新. VDES中频偏估计与相位跟踪算法研究[J]. 电子测量技术, 2020, 43(23):51-56.
	FAN J H, WANG J X. Research on frequence offset estimation and phase tracking algorithm in VDES[J]. Electronic Measurement Technology, 2020, 43(23):51-56. (in Chinese)
[7]	MENGALI U, MORELLI M. Data-aided frequency estimation for burst digital transmission[J]. IEEE Transactions on Communications, 1997, 45(1): 23-25. doi: 10.1109/26.554282 URL
[8]	TRUCHACHEV D, MCNUTT D. Joint packet detection and decoding for maritime data exchange systems[C]// Proceedings of OCEANS 2015-MTS/IEEE.Washington, D.C.,US:IEEE, 2015:1-6, doi: 10.23919/OCEANS.7404597.
[9]	LÁZARO F, RAULEFS R, WANG W, et al. VHF data exchange system (VDES):an enabling technology for maritime communications[J]. CEAS Space Journal, 2019, 11:55-63. https://doi.org/10.1007/s12567-018-0214-8. doi: 10.1007/s12567-018-0214-8 URL
[10]	史珂. VDES中QPSK信号同步参数估计研究[D]. 天津: 天津理工大学, 2019.
	SHI K. Study on synchronization parameters estimation of QPSK signal in VDES[D]. Tianjin: Tianjin University of Technology, 2019. (in Chinese)
[11]	邓渭伟. VDE中π/4-QPSK信号检测方法研究[D]. 天津: 天津理工大学, 2017.
	DENG W W. Research of detection method of pi/4-QPSK signal in VDE[D]. Tianjin: Tianjin University of Technology, 2017. (in Chinese)
[12]	张嘉良. 基于FPGA的载波同步与位同步系统的设计[D]. 大连: 大连海事大学, 2016.
	ZHANG J L. Design of carrier synchronization and bit synchronization system based on FPGA[D]. Dalian: Dalian Maritime University, 2016. (in Chinese)
[13]	OERDER M, MEYR H. Digital filter and square timing recovery[J]. IEEE Transactions on Communications, 1988, 36(5):605-612. doi: 10.1109/26.1476 URL
[14]	荣师洁. 天地一体化VDES关键技术的研究[D]. 南京: 南京理工大学, 2019.DOI:10.27241/d.cnki.gnjgu.2019.000861.
	RONG S J. Research on key technologies of space-earth integration VDES[D]. Nanjing: Nanjing University of Science and Technology, 2019.DOI:10.27241/d.cnki.gnjgu.2019.000861. (in Chinese)
[15]	董晓璇, 程嗣怡, 罗朝义, 等. 一种基于加权递推滤波的门限优化检测方法[J]. 现代雷达, 2019, 41(1):19-25.
	DONG X X, CHENG S Y, LUO C Y, et al. A threshold optimization detection algorithm based on weighted recursive filter[J]. Modern Radar, 2019, 41(1):19-25. (in Chinese)
[16]	仲雅莉, 吴俊辉, 刘炫, 等. 一种基于CORDIC算法的高精度反正切求解[J]. 电子技术应用, 2022, 48(1):12-17.
	ZHONG Y L, WU J H, LIU X, et al. A high precision arctangent solution based on CORDIC algorithm[J]. Application of Electronic Technique, 2022, 48(1):12-17. (in Chinese)
[17]	王硕同. ASM及VDE信号解调译码技术研究与实现[D]. 南京: 南京理工大学, 2021.DOI:10.27241/d.cnki.gnjgu.2021.000977.
	WANG S T. Research and implementation of ASM and VDE signal demodulation and decoding technology[D]. Nanjing: Nanjing University of Science and Technology, 2021.DOI:10.27241/d.cnki.gnjgu.2021.000977. (in Chinese)
[18]	朱鸿明. ASM基带信号处理技术研究与实现[D]. 南京: 南京理工大学, 2019.DOI:10.27241/d.cnki.gnjgu.2019.002160.
	ZHU H M. Research and Implementation of ASM Baseband Signal Processing Technology[D]. Nanjing: Nanjing University of Science and Technology, 2019. DOI:10.27241/d.cnki.gnjgu.2019.002160. (in Chinese)
[19]	苏正扬. 星载AIS基于波形匹配的频偏时延联合估计[J]. 电子元器件与信息技术, 2018, 2(6):101-107.
	SU Z Y. Frequency offset time delay combined estimation of spaceborne AIS based on waveform matching[J]. Electronic Components and Information Technology, 2018, 2(6):101-107. (in Chinese)
[20]	范家辉. VDE中8PSK和16QAM信号解调技术的研究与实现[D]. 南京: 南京理工大学, 2021.DOI:10.27241/d.cnki.gnjgu.2021.001006.
	FAN J H. Research and Implementation of 8PSK and 16QAM Signal Demodulation Technology in VDE[D]. Nanjing: Nanjing University of Science and Technology, 2021.DOI:10.27241/d.cnki.gnjgu.2021.001006. (in Chinese)
[21]	王巍, 乔钢, 王玥, 等. 多输入多输出正交频分复用浅海水声通信打孔判决反馈信道估计算法[J]. 兵工学报, 2013, 34(9):1116-1124. doi: 10. 3969/ j. issn. 1000-1093. 2013. 09. 010
	WANG W, QIAO G, WANG Y, et al. Decision feedback estimation of multiple-input multiple-output orthogonal frequency division multiplexing channel based on punching technique via UWA shallow sea[J]. Acta Armamentarii, 2013, 34(9):1116-1124. (in Chinese) doi: 10. 3969/ j. issn. 1000-1093. 2013. 09. 010