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smd
04-29-2011, 10:27 PM
I collected data at a sampling rate of 100Hz on a force platform. Is there a way to change the data set in excel so that I only get data that would occur at a sampling rate of 60Hz? For example, if I collected at 1000Hz and I wanted data for only 100Hz I would select every 10th row in excel. Or can I multiply the data by a certain number that may be equal to what it would be if it was sampled at 60Hz?

paulglazier
04-30-2011, 05:09 AM
You can interpolate your time series data to get the temporal resolution you require. The only interpolation facility for Excel I know of and have used is: http://www.xlxtrfun.com/XlXtrFun/XlXtrFun.htm. However, you must be aware of the underlying assumptions you are making and their consequences. I'd seriously suggest you consult the following chapters as what you are proposing and the sampling rates you are using are non-standard:

Challis, J.H. (2008). Data processing and error estimation. In Biomechanical Evaluation of Movement in Sport and Exercise: The British Association of Sport and Exercise Sciences Guidelines (edited by C.J. Payton & R.M. Bartlett), pp.129-152. London: Routledge.

Derrick, T.R. (2004). Signal processing. In Research Methods in Biomechanics (edited by D.G.E. Robertson, G.E. Caldwell, J. Hamill, G. Kamen & S.N. Whittlesey), pp. 227-238. Champaign, IL: Human Kinetics.

jvanrenterghem29
05-01-2011, 07:21 AM
Dear Paul,
You can do this easily with the Biomechanics Toolbar in Excel. This is a free toolbar that I developed with tools for basic biomechanics procedures. You will need to install it, and allow macros in the process as it is based on macros. All procedures are based on a select-process-paste basis. The frequency change command does simple interpolation between points (info in the help file through start menu after installation), and allows you to reduce in frequency (e.g. from 100Hz to 60Hz). Link to the installation file and information can be found on http://www.staff.ljmu.ac.uk/spsjvanr/BiomechanicsToolbar.html.
Let me know if you'd have any problems installing or using the toolbar.
Regards,
Jos


I collected data at a sampling rate of 100Hz on a force platform. Is there a way to change the data set in excel so that I only get data that would occur at a sampling rate of 60Hz? For example, if I collected at 1000Hz and I wanted data for only 100Hz I would select every 10th row in excel. Or can I multiply the data by a certain number that may be equal to what it would be if it was sampled at 60Hz?

paulglazier
05-01-2011, 02:34 PM
Thanks for sharing this Jos - nice little add-on.