Research on GRI Combination Design of eLORAN System
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摘要: 针对增强型罗兰(eLORAN)系统增补发射台站建设中的组重复周期(GRI)选择问题,该文主要从数学的角度出发,提出一种基于交叉干扰率的筛选算法。该算法首先考虑了最小可用组重复周期以及秒信息量的要求,并在此基础上通过比较与临近的罗兰C台站间的相对交叉干扰率进行1次筛选;之后通过排列组合进行两两比较并2次筛选;最后,综合考虑数据率要求、系统规范、无交叉干扰等条件,得到最优组重复周期组合。随后,鉴于新型eLORAN系统的高精度授时要求,在GRI最优组合中进行了优选。分析结果表明,该方法得出的优选组合的平均交叉干扰率与现有导航台链相当,同时可兼顾授时需求,可以为高精度地基授时系统建设提供参考性建议和理论依据。Abstract: To solve the problem of Group Repetition Interval (GRI) selection in the construction of the enhanced LORAN (eLORAN) system supplementary transmission station, a screening algorithm based on cross interference rate is proposed mainly from the mathematical point of view. Firstly, this method considers the requirement of second information, and on this basis, conducts a first screening by comparing the mutual Cross Rate Interference (CRI) with the adjacent Loran-C stations in the neighboring countries. Secondly, a second screening is conducted through permutation and pairwise comparison. Finally, the optimal GRI combination scheme is given by considering the requirements of data rate and system specification. Then, in view of the high-precision timing requirements for the new eLORAN system, an optimized selection is made in multiple optimal combinations. The analysis results show that the average interference rate of the optimal combination scheme obtained by this algorithm is comparable to that between the current navigation chains and can take into account the timing requirements, which can provide referential suggestions and theoretical basis for the construction of high-precision ground-based timing system.
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表 1 我国长波各发射台组重复周期分配
台链名称 GRI(μs) 主台 第1副台 第2副台 TOCI(s) BPL授时台 60000 蒲城 – – 3 北海台链 74300 荣城 宣城 和龙 743 东海台链 83900 宣城 饶平 荣城 839 南海台链 67800 贺县 崇左 饶平 339 表 2 TOCI小于20 s的GRI取值
GRI(μs) TOCI(s) GRI(μs) TOCI(s) GRI(μs) TOCI(s) GRI(μs) TOCI(s) 40000 2 50000 1 65000 13 80000 4 42500 17 52000 13 68000 17 81250 13 43750 7 55000 11 68750 11 85000 17 44000 11 56000 14 70000 7 87500 7 45000 9 56250 9 72000 18 90000 9 47500 19 62500 3 75000 3 93750 3 48000 12 64000 16 76000 19 95000 19 表 3 与BPL交叉干扰较小的GRI取值
GRI(μs) TOCI(s) 交叉干扰周期T0(s) 相互干扰率(%) 42500 17 1.02 11.11 7.87 43750 7 2.1 7.62 5.56 47500 19 1.14 9.94 7.87 56250 9 0.9 8.29 7.77 62500 1 1.5 7.56 7.87 68750 11 3.3 4.85 5.56 76000 19 1.14 12.28 15.56 81250 13 3.9 4.10 5.56 85000 17 1.02 11.11 15.74 87500 7 2.1 5.40 7.87 93750 3 1.5 4.97 7.77 95000 19 1.14 9.94 15.74 表 4 备选组重复周期互交叉干扰率(%)
互干扰对应关系 备选组合(μs) 47500/
81250/
9375081250/
93750/
9500047500/
68750/
8125068750/
81250/
9500042500/
81250/
937501–2 4.10 7.64 4.85 8.81 4.10 7.02 8.81 7.02 10.42 7.84 1–3 3.56 3.51 4.10 3.51 3.56 7.02 4.10 7.02 4.85 7.84 2–3 7.64 3.51 8.81 7.64 8.81 3.56 10.42 4.10 8.81 1–BPL 9.94 4.10 9.94 4.85 11.11 7.87 5.56 7.87 5.56 7.87 2–BPL 4.10 4.97 4.85 4.10 4.10 5.56 7.77 5.56 5.56 5.56 3–BPL 4.97 9.94 4.10 9.94 4.97 7.77 15.74 5.56 15.74 7.77 合计 78.36 79.21 80.09 80.94 81.18 均值 6.53 6.60 6.67 6.75 6.76 表 5 TOCImax取58 s与64 s时最优GRI组合对比①
TOCImax
(s)平均TOCI
(s)GRI组合
(μs)总交叉
干扰率(%)平均交叉
干扰率(%)平均数
据率(bit/s)58 41.33 46400/
66250/
8125062.03 5.17 114.23 64 46 51200/
76250/
8125048.32 4.86 104.89 -
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