IQ demodulation from specific rate We have an acquisition hardware in our lab that acquires and digitizes data from a source generating band-limited signal in the MHz range. It samples the signal at a rate of 4 times the center frequency $f_0$ of the signal. In the documentation, they say that this specific sample rate makes it easier to convert the RF samples to demodulated IQ samples.
How would $f_s=4f_0$ make the demodulation easier? I have been using Hilbert transform to achieve the demodulation (the old-fashioned way). But, if there is any shortcut offered by this specific sample rate, that would be really helpful.
Thanks.
To get IQ data from a bandlimited signal centered at f0, with a bandpass well inside f0-f0/2 to f0+f0/2, and using a sample rate of fs=4*f0, you can simply keep 2 successive samples out of every 4, and ignore the rest.  Take every 4th sample, put them in the I channel, take the samples right after those and put them in the Q channel, and throw away the 3rd and 4th sample out of every 4 samples (I Q ignore ignore I Q ignore ignore I Q ignore ignore ... etc.).  The result is an IQ signal at a sample rate of f0.