filtering out harmonic trend

[Rafael Laboissiere]

* Francesco Potorti` <Potorti at isti.cnr.it> [2007-12-04 13:39]:

> I have a 200,000 samples measurement, which is a sort of noise with
> bandwidth in the order of the inverse of 500 samples.  Superimposed to
> this noise there is a very slow sinusoid with a period of about 300,000
> samples.  This means that my measurements do not even see a complete
> cycle of this sinusoid.
> 
> I want to estimate the sinusoid (in order to remove it from the
> measurement).  So I need some sort of very-low pass filter.  However,
> usign a simple causal low-pass filter would give me a delayed output.
> Can anyone suggest some keyword for a noncausal filter to look for?  I
> guess that it could be simple, because the bandwidths of signal and
> noise are so far away each other.

filtfilt
 
-- 
Rafael