**From:** Ingraham, Andrew (*Andrew.Ingraham@compaq.com*)

**Date:** Sat Mar 31 2001 - 14:36:37 PST

**Next message:**Michael Nudelman: "RE: [SI-LIST] : Nyquest Sampling Rate"**Previous message:**ARiazi: "Re: [SI-LIST] : Diode Modeling"**Maybe in reply to:**AA: "[SI-LIST] : Nyquest Sampling Rate"**Next in thread:**Michael Nudelman: "RE: [SI-LIST] : Nyquest Sampling Rate"

*> Can any one explain to me how you can recover a
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*> periodic signal form only 2 samples. I can understand
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*> the math but I am having difficulty visualizing this.
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*> Draw me any 2 points in the time domain and I can make
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*> endless number of periodic signal go through them?
*

The bandwidth limit works both ways; both when sampling a signal and when

restoring it from the sampled points. Thus, given _slightly_more_than_ 2

points per cycle, you can reconstruct the one sinewave that must have been

the band-limited original. No signal other than a sinewave will do, because

any other shape has harmonic frequencies that would violate the Nyquist

criteria.

However, given exactly 2 samples per cycle, indeed there are an infinite

number of sinewaves that you could draw that pass through those points,

because you don't know both the amplitude and the phase of the original.

Two samples per cycle is the borderline case. You really need slightly more

than 2 per cycle.

Andy

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**Next message:**Michael Nudelman: "RE: [SI-LIST] : Nyquest Sampling Rate"**Previous message:**ARiazi: "Re: [SI-LIST] : Diode Modeling"**Maybe in reply to:**AA: "[SI-LIST] : Nyquest Sampling Rate"**Next in thread:**Michael Nudelman: "RE: [SI-LIST] : Nyquest Sampling Rate"

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