Question: Hi, I have one question about signal to noise ratio (SNR). Suppose the received sky signal consists of many astronomical sources, how do we define the SNR? Assume SNR is -20dB , the power of each source is 1, and 2 sources in total, what is the power of the noise here? Is it 100 or 200? — Shui
Answer: The noise is independent of the number of sources in a measurement. The noise in a measurement is determined by a variety of factors dependent upon the sensitivity of the receiving system and the observing conditions (such as weather). In your example the noise power would be 200.