摘要
中国于1983年至1984年在五条路径(距离1000至7300km,频率5至15MHz)上的短波场强测量结果表明,其长期衰落(日—日波动)的月标准偏差的平均值为4.4dB。同时传输的不同频率场强长期衰落之间的相关系数平均值为10%,其中相同路径时为18%,不同路径时为3%。对相关系数平均值所作统计检验指出,当显著性水平为1%时,对于不同路径,可以认为基本不相关;对于相同路径,则存在一定相关性。对用两个频率同时传输时的接收可靠度所作近似分析表明,当相关系数低于20%时,对可靠度影响很小,因此,可以按不相关计算。
In China,HF field strength measurements were made from 1983 to 1984 in 5 paths(With distamces from 1000 to 7300km,frequencies from 5 to 15MHz).It's shown that the mean value ef the monthly standard deviations for long-ferm fading (day-to-dayfluctuation)is 4.4 dB。For simnltaneous transmissions on different frequ- encies,the mean value of the correlation coefficients between the long-term fading of their field strength(?)s is 10%,among which that for different paths is 18% and that for same paths is 3%.lt's shown by statistical test to the mean value of the conela- tion coefficients,that,for significance level of 1%,it may be considered to be in- dependent for different paths,but for same paths there exists certain correlation. By approximate analysis to the reception reliability for Simultaneous transmission with tvo frequencies,it's shown that for correlation coefficient less than 20%,its im- pact on reliability is very small.Therefore,calaclation can be made by assuming no correlation.
出处
《电波科学学报》
EI
CSCD
1989年第4期28-33,共6页
Chinese Journal of Radio Science
