On 31.7.2012. 12:54, Wen Xue wrote:
5ms moving-average doesn't sound very right for it cuts off anything below
200Hz, no matter how much one upsamples it. However it is probably "just fine"
to subtract a DC measured 500ms ago from the current waveform because the DC
shouldn't change much in that time or it can't be DC. This subtraction you can
write as a anti-DC filter which is FIR with a big delay on the unwanted part but
no delay on the wanted part. There might be some DC left - but probably
significantly suppressed - depending on how DC-ish it is.
Is this the same/similar to what I mentioned in the first post:
<<
Then there is the modification
(http://www.dsprelated.com/showmessage/80739/2.php, Andor's post) to subtract
the moving average from the _current_ sample (instead of the one corresponding
to the middle of the moving average filter) but this supposedly makes the filter
minimal-phase instead of linear-phase so it is still a no go (at least AFAICT
from my limited knowledge).
>>
?
--
Domagoj Saric
Software Architect
www.LittleEndian.com
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