Answer:
10.0 mW
Explanation:
By definition, the SNR of any system is expressed as follows:
[tex]SNR (dB) = 10 log (\frac{S}{N})[/tex]
where
S = average power of the signal
N= average noise power
In this case this relationship can be written as follows, repalcing by the givens:
[tex]SNR (dB) = 10 log (\frac{S}{4mW}) = 4 dB[/tex]
Rearranging terms, and taking log₁₀ on both sides, we have:
[tex]10* log \frac{S}{N} = 4 dB \\ log \frac{S}{N} = 0.4 \\\ \frac{S}{N} = 10^{0.4} \\ S= 4e-3 W* 10^{0.4} = 10.0 mW[/tex]
⇒ Pavg = 10 mW
