Ok, so I recently started playing around with an SDR in an effort to challenge and educate myself. So, let's say the sampling rate (Fs) is 3MHz and of those we grab 3M samples. Now we are left with 3M samples consisting each of an IQ pair. Complex data. My understanding is that I would perform an FFT using the entire sample, consisting of IQ as the input for the FFT which would yield another complex answer. From this, calculate the magnitude and plot starting from 0? I'm not entirely positive which samples to throw out, which ones to keep, and in which order to plot them.
Do I perhaps separate the real and imaginary prior to the FFT for the first 1.5M samples, perform an FFT for 1.5M of I and FFT for 1.5M of Q and plot the real to the right of 0 and the imaginary to the left of 0? Throwing out the rest of samples from 1.5-3M?
Any help is very much appreciated. Thanks all.