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## Re: FFT time-shift/interpolation

 From: Steve Thompson Subject: Re: FFT time-shift/interpolation Date: Thu, 16 Apr 2009 07:13:59 -0700

Hi,

In the past, I've had luck with a so-called continuously variable digital
delay (CVDD) algorithm by Farrow:

C. W. Farrow, ``A Continuously Variable Digital Delay Element,'' in
Proceedings for the IEEE International Symposium on Circuits and Systems,
pp. 2641--2645, 1988.

You can see how I use it here: http://elsteve.com/code/20060112_multipath/
and more specifically, here:
http://elsteve.com/code/20060112_multipath/tap_delay_line.m
and
http://elsteve.com/code/20060112_multipath/test_tap_delay_line.m

I just did a search for "farrow matlab" and see this Farrow technique is
used quite a bit.

Good luck.

Steve

On Thu, Apr 16, 2009 at 5:13 AM, shivan wrote:

Hi everybody, I trying to shift (circular) a real signal by delta, so I do :

a = [1:10] %as a test
b = ifft( fft(a) .* exp(-2*i*pi*[0:9]*delta/10))

so, yeah, that's cool. but I'd like to use a non-integer delta, like 0.2.
But of course I'll end up with b being an array with imaginary number.
I could interpolate to get more samples and only pick the on I need, but
it's unpractical for values like 0.3452.

would someone please have an idea?

regards.
--
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