TA的每日心情 | 开心 2024-5-17 22:05 |
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签到天数: 223 天 [LV.7]常住居民III
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[题解]
1) 求可用(Eb/n0)T
dB
(Eb/n0)T =4.5 + 2=6.5 dB
2)求载波有效信息速率Rb
Rb= Rc Rs(log2M)
Rb=(1/2)×41.53×106×(log24)
=41.53×106 Symbols/s
3)求可用(C/n0)T
dBHz
(C/n0)T = 6.5+10lg(41.53×106)
=6.5+10×6+10 lg41.53
=6.5+60+16.2=82.7 dBHz
4)求下行链路(C/n0)D
dBHz
(C/n0)D =(C/n0)T -βU
=82.7-(-0.5)=83.2 dBHz
5)求下行工作波长λ
λ= c/f = 3×108/(12380×106)=0.0242 m
6)求下行自由空间传播损耗Lo,D
dB
Lo,D =10lg(4×3.14×37500×103/0.0242)2
=205.8 dB
7)求下行接收站品质因数(优值)(G/T)D
dBHz
(G/T)D =(C/n0)D-EIRPs+Boo,s+10lgm+ Lo,D+△LD+Lr,D+10lgk
=83.2-50+0.5+10lg1+205.8+1+6+(-228.6)
=17.9 dBK-1
8)求接收天线增益Gr
dBK-1
10lgGr=(G/T)D+10lgT
=17.9+10lg100=37.9 dB
Gr=1037。9/10=6166 (倍)
9)求天线口径D
Gr=(πD/λ)2η
则卫星接收天线口径:D=0.0242/3.14×√(6166/0.55)=0.82 m
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