While researching SNR improvement techniques, I came across many techniques, mostly the application of digital filters and windowing. Shortly, I read an article that said that performing decimation can be used to improve the SNR of a signal, by a factor of 3dB (half in linear terms) for every time the decimation is doubled.
From my understanding of decimation, we basically throw away a certain portion of samples for every few samples taken, meaning that if we have a decimation of 3, we only keep 1 of every 3 sampled, discarding the other two. Would it be possible for anyone to explain to me, whether or not this is true? Can decimation be used as a SNR improvement technique? And if yes, why?
Edit: I forgot to mention that I also read that decimation first applies a low pass filter, before discarding the samples. Is this true? And if yes, how would this be implemented? Would this be the construction of a (digital) FIR filter?