Numerically controlled oscillator: Difference between revisions

Revision as of 04:45, 27 July 2020

Revision as of 04:46, 27 July 2020

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Another related spurious generation method is the slight modulation due to the GRR outlined above. The amplitude of these spurs is low for large N and their frequency is generally too low to be detectable but they may cause issues for some applications.<ref name="Grzeg"/>

One way to reduce the truncation in the address lookup is to have several smaller lookup tables in parallel and use the upper bits to index into the tables and the lower bits to weigh them for linear or quadratic interpolation. Ie use a 24-bit phase accumulator to look up into two 16-bit LUTS. Address into the truncated 16 MSBs, and that plus 1. Linearly interpolate using the 8 MSBs wasas weights. (YouOne could instead use 3 LUTs instead and quadratically interpolate). This can reduceresult thein memorydecreased useddistortion andfor decreasethe distortionsame amount of memory.

===Amplitude truncation spurs===