Get phase precisely through longer sampling time

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WengCheng

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Hello,
some months ago someone told me that it is a common approach to sample a sinusoid signal over a longer period of time to get the phase more accurately. Is it just calculating an average over the sampled phase information, or is there any other mathematical theory behind?
Is there any literature on this topic?
 

Hi,

someone told me
Click to expand...
... then why not ask him?

From mathematics: You need just 3 samples (each 120° apart) to be able to calculate amplitude and phase precisely.

How precise?
It depends on the input values. If the input values are "ideal" then the phase and amplitiute values are "ideal", too.

Klaus
 


Yes it's basically just averaging. All samples have noise. If you make a decision with a few samples it will be more likely wrong than making a decision with many samples.

In my experience 10-100 cycles is a good number with probably diminishing returns after that. Of course it depends on many other things.
 

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