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inti
Posts:
23
Registered:
5/4/14


filter low pass gives me a faster data
Posted:
Jul 4, 2014 9:13 AM


I'm using a SensorTag which contain 6 sensors. here i'm interessing just for KJ9's accelerometer( data sheet of Kionix KJ9's accelerometer (http://www.willow.co.uk/html/components/com_virtuemart/shop_image/product/OEM%20Component%20Level%20Accelerometers/pdfs/KXTJ91007%20Specifications%20Rev%204.pdf)
10hz is a sampling frequency, and i choose a 0.6 as a cutoff frequency (arbitrairy).
My goal is to analyze acceleration's data and isolate a gravity's acceleration. For this reason, i applied a butterworth filter (low and high). Normally i should applied just a low filter, but the problem that gives me a filter's data value > data before applied a filter. for example :
data before filtred : 0.34 0.25 0.31
data after filtred: 0.08 0.27 0.34
(sometimes data after filtred is faster than data before filtred) it is normal?
Thanks in advance for any suggestion



