Adding SNR from multiple detectors

[sparkle_pony]

I am looking at the same object with two detectors. The SNR on each is 2, which is a low probability of detect given a single sensor. However, if I fuse the two what would be the SNR then? Would it be additive (SNR=4) or rss (SNR=2×sqrt(2)) or something more complicated?

 

[meBigGuy]

Correlated signals add, uncorrelated signals are sqrt(sum of squares).

If the noise is uncorrelated between the detectors, and the signal is correlated, you will improve the SNR