武昌同步卫星信号振幅闪烁功率谱

本文利用自制的微机数据采集与分析系统,处理了1985年12月至1986年6月在武昌接收日本ETS-Ⅱ卫星信标136MHz信号所观测到的振幅闪烁。共分析了133例闪烁功率谱得出,谱指数随闪烁指数S_4的增加有增大的趋势,平均谱指数值为3.1;大多数的对数功率谱曲线都在低频部分平坦或以略小于1的斜率上升,而在高频部分以-2.5～-4.0的斜率迅速下降;有1 3例功率谱在高频部分发生“折断”现象,即负幂律谱有两个谱指数,发生折断的频率f_b约为0.07Hz,相应的电离层不规则结构的空间尺度约为280m。

SPECTRA OF VHF AMPLITUDE SCINTILLATION AT WUCHANG

The amplitude scintillation spectra of VHF signal transmitted from the ETS-Ⅱ and received at Wuchang （Geog. 30.5°N, 114.6°E）, a lower mid-latitude station, are studied. Analyses of 133 scintillation samples recorded during Dec. 1985-June 1986 show that the spectral index has a mean value of 3.1 and the spectral slopes steepen with increasing S4, Most of the spectrograms consist of a relatively fiat or sloping down low frequency part and a roll-off withslopes -2.5^-4.0 over higher frequencies range for amplitude scintillation. A few spectrahave been found with a clear break in spectral slope at 0.07 Hz, corresponding to a scale length of about 280 m for ionospheric irregularities.