CAJ | 학술논문

分析了大圆距离约770km的斜向探测电路的实测数据，统计了信号幅度衰落的累积分布、衰落深度、衰落率、基本相关时间、基本不相关时间和多普勒展宽共六个常用于描述短波信道时间选择性衰落特性的参数，还进行了不同积累时间频谱的分析。结果表明：不同传播模式，多普勒域幅度衰落66％较为符合正态分布，时域幅度衰落73％较为符合维布尔分布；电离层稳定时，幅度衰落自相关的特征值较大，而且自相关半径较为接近基本不相关时间；有效积累时间内，积累时间越长，多普勒分辨力越高，信号更加锐化；积累时间大于有效积累时间时，相干性变差，积累效果恶化。
분석료대원거리약770km적사향탐측전로적실측수거，통계료신호폭도쇠락적루적분포、쇠락심도、쇠락솔、기본상관시간、기본불상관시간화다보륵전관공륙개상용우묘술단파신도시간선택성쇠락특성적삼수，환진행료불동적루시간빈보적분석。결과표명：불동전파모식，다보륵역폭도쇠락66％교위부합정태분포，시역폭도쇠락73％교위부합유포이분포；전리층은정시，폭도쇠락자상관적특정치교대，이차자상관반경교위접근기본불상관시간；유효적루시간내，적루시간월장，다보륵분변력월고，신호경가예화；적루시간대우유효적루시간시，상간성변차，적루효과악화。
The test data of oblique ionospheric sounding circuits for great-circle distance of 770 kilometers are analyzed, and six parameters（ cumulative distribution of signal amplitude fading,fading depth ,fading rate,BCT （base correlation time）.BNT （base noncorrelation time） and doppler spreading are obtained that describe the time selective fading property of the shortwave channel in common use, and then the spectra for different CIT （correlation-integration-time） are studied. The result reveals： for different propagation mode, 66 percent of the data obviously satisfied with normal distribution in doppler-domain, and 73 percent of the data relatively satisfied with Weibull distribution in time-domain. For the steady ionosphere, eigenvalue of amplitude fading autocorrelation is rather large, and the autocorrelation-ra- dius more approached BNT. Within valid CIT, the long CIT can obtained high doppler-resolution and more sharpening signal, otherwise the correlationthen became bad and the integration effect deteriorated when the CIT is long than the valid CIT. It is suggest that the system under shortwave channel should se- lect less of pattern and steady high frequency as possible.