Question

A signal with 200 milliwatts power passes through 10 devices, each with an average noise of 2 microwatts. what is the snrdb

Answer 1

Given that the signal is 200 mW, you will convert this into Wats;

200/1000 = 0.2W

Noise = 10×2×10⁻⁶=2×10⁻⁵

Therefore the SNR = Average signal power÷Average noise power

0.2/2×10⁻⁵=10000

Thus:

SNR db = 10 ㏒₁₀ (SNR)

So in this case 10 ㏒₁₀ (10000) = 40.