Unformatted text preview: PI ,Total
3 Pmin where Pmin is the minimum input signal power for a specified output SNR. Since we already
know Pmin for 15dB SNR at the output, we just need to plug it in the above formula. Then DR 2
3 5.5 ( 105.5) 66.67 ( dB ) [12-7 Solution]
The dynamic range of the receiver before the addition of the attenuator is:
(i) DRbef ore = [ (i) PI
23 = [3 .
k (Ts + Te )Bn S N Ro,min
(i) When the attenuator is added the input intercept changes to PI L and the
eﬀective input temperature of the system increases from Te to To (L − 1) + Te L
so the new dynamic range is:
(i) DRw/atten = [ 2
PI L3 .
k (Ts + To (L 1) + Te L)Bn S N Ro,min In order for the new dynamic range to be larger than the old dynamic range,
the following inequality must hold:
Ts + To (L − 1) + Te L
Ts + Te
Rearrange the inequality to ﬁnd:
Ts > To .
Thus, if the source (antenna) temperature is greater than To , then adding the
attenuator will increase the system dynamic range. 1 [12-9 Solution]
Since gain compression ca...
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