A Scrapbook of Digital Signal Processing


Rounding (especially binary rounding) is often done by adding 1 to the number. Be careful -- if the number is positive, add +1; if the number is negative, add -1. Otherwise, the rounding is done asymmetrically, with what can be rather deceptive results. Asymmetrical rounding at the end of each stage of a 16-bit fixed-point FFT, for instance, will cause an unexpectedly low noise floor with periodic spikes, instead of the expected smooth noise floor level at its normally higher value.

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