Hi,
There is trivial ways to estimate phase and amplitude of a sine using
linear methods. I saw however none of these properly referenced or
described. It would have been good to see those approaches attempted in
parallel on the same data and compare their performance with the
proposed approach. It seemed "fuzzy" how it worked, and that is never a
good sign in a scientific article, especially as it is n the heart of
the method described in the paper. The actual method should be named,
referenced and then also referenced with "as implemented by..." and we
only got the last part.
Cheers,
Magnus
On 11/23/2017 01:34 PM, [email protected] wrote:
Hi,
just my two cents on sine wave fitting.
A undamped sine wave is the solution of the difference equation
sig(n+1)=2*cos(w)*sig(n)-sig(n-1)
This is a linear system of equations mapping the sum of the samples n+1 and
n-1 to the sample n. The factor 2*cos(w) is the unknown. The least-squares
solution of the overdetermined system is pure linear algebra, no nonlinear
fitting involved. The trick also works for a damped sine wave. Care must be
taken for high 'oversampling' rates, it works best for 4samples/sinewave,
ie near Nyquist/2.
Cheers
Detlef
DD4WV
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