# Tag Info

3

Another way to look at it is that an IQ ADC is really taking 2 independent (not added together) samples per IQ sample. Thus the rate of information gathered is double from a just scalar sampling at 22 MHz. The 90 degree offset between the 2 IQ sample components allows capturing phase information that can help a complex FFT (et.al.) differentiate between ...

4

The Nyquist limit is half the sampling rate because otherwise you can't distinguish a signal at a frequency $x$ from a signal at $f_s - x$ which starts 180° out of phase from the first one — they give exactly the same sequence of real samples. But quadrature sampling gives exactly the phase information needed to resolve this ambiguity. Knowing $\sin \omega t$...

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Are the two channels added together? Yes and no. The whole point of collecting I and Q is so they can be treated as real and imaginary parts of a single complex sample. This is one of the key methods of SDR. This answer explains it well: https://electronics.stackexchange.com/questions/39796/can-somebody-explain-what-iq-quadrature-means-in-terms-of-sdr

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