Classical filter artifact, depending on your filter architecture you have a finite (or more or less infinte) filter settling time.
Usual ways to overcome:
- read more data before the region of interest and cut it.
- mirror the start of your data and cut it.
- remove the offset of your data or init the filter with the first startpoint or ....
- finally a combination of some or all of it 😄
the step response of your filter is a good indication for the length of your settle time ( number of additional samples needed) 😉
If you read the data continously anyway, do the filter init only once at the start. (that boolean input, see help of filter vi)
Hint: Try to avoid the express vis ..
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'