Abstract:

The two transpolar shortwave time signal circuits,Moscow and Irkutsk to the Great Wall Station in Antarctica, are used to study the fading characters for shortwave long circuit.The ionospheric shortwave channels for the two circuits are rapid fading channels,its signal amplitude fading obeys the Rayleigh distribution essentially and this distribution is independent of time,frequency,distance and geographic location.The fading depth is different for the two circuits. For Moscow to the Great Wall Station circuit,the lower the frequency,the larger the fading depth.But for Irkutsk to the Great Wall Station circuit,there is little relationship between the fading depth and frequency.It seems that the relationship between fading depth and frequency is controlled by the factors such as location,distance etc.The higher the frequency, the higher the fading rate for the two circuits.