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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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In Reply to: Think About It... posted by Todd Krieger on August 28, 2003 at 00:57:23:
It would be so much easier for us, and for yourself, if you stopped using misty terms like "restore resolution", "up/downconversion", "time resolute" etc.Your assertion is true but only for the original input samples to
a FIR filter that is a sufficient approximation of the Sinc function
in the sense that all of its zero-crossings are equally spaced at
1/fs and where no scaling is ever applied. Those samples can be
described with the original word length. In all other cases,
i.e. the interpolated samples, or filters that do not obey above restrictions, truncation to the original word length leads to distortion relative to the intended result. Since truncation is inevitable in a practical filter with any ambitions towards fidelity, measures to linearise the truncation are to be adopted.Please convolve this twice oversampled sequence with the triangular filter below:
7 0 13 0 2 0 6 0
y[k] = 0.5x[k-1]+x[k]+0.5x[k+1]
thus
7 10 13 7.5 2 4 6 ...
which is not
7 10 13 7 2 4 6 ...
But of course if you feel that that '7.5' is arbitrary ...
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Follow Ups
- Re: Think About It... - Werner 08/28/0301:38:26 08/28/03 (0)
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