[sdiy] Sampling Aliases and Images

[Anthony Carrico]

On 11/25/20 6:38 AM, Richie Burnett wrote:
>> Would it be correct to say that half of the images are mirror images?
> 
> I would say Yes.  Half of the infinitely repeating images of the
> original spectrum in a sampled data set are spectrally reversed or
> mirrored.

These are copies of the negative frequencies. It's really just a
coincidence that they are he mirror image of the positive frequencies;
they could be anything. This coincidence occurs when the signal is real
valued (vs. complex). In the real valued case, the original signal is
mirror imaged at zero frequency, so when you shift it you are seeing
those negative frequencies.

My first post to the list--I just subscribed!

-- 
Anthony Carrico