| 摘要 |
PURPOSE:To reduce greatly an effect of attenuation due to a rainfall, by detecting the amount of noise increment owing to the rainfall attenuation and then adding this amount to the reception level output voltage through an appropriate operation to apply them to an antenna control device. CONSTITUTION:The amount of reception level drop due to an antenna direction error is referred to as AdB, and the amount of reception level drop owing to a rainfall is BdB, respectively. The output voltage fluctuation DELTAVC of a loop filter 9 is shown as -[KP.KS(A+B)]/(KI.KP.KS)=-(A+B)/KI. On the other hand, the increase extent TKO(K) of the noise temperature in case the attenuation BdB is caused by a rainfall is shown as Tm(1-1/b), where Tm is the average absorption temperature of the atmosphere with b=log<-1>B/10. When the system noise temperature of an earth station is referred to as TO deg.K, the full noise temperature TS deg.K is equal to TK+TO. The output noise electric power N1 of a band pass filter 4 becomes as N1=NO-DELTA(C/N), where the noise electric power is referred to as NO when no reduction is given to the reception level. |
