We now show mathematically that the DFT sinusoids are exactly orthogonal.
where the last step made use of the closed-form expression for the sum
of a geometric series (§6.1). If , the
denominator is nonzero while the numerator is zero. This proves
A Fixed-Point Introduction by Example
Handling Spectral Inversion in Baseband Processing
Understanding the Phasing Method of Single Sideband Modulation
An Interesting Fourier Transform 1/f Noise