Friday, January 16, 2009

I learned a lot today about data reduction. First off.... if there is drift in the accel data, it is most likely due to temperature effects. This I knew. What I didn't do though and needed to was HIGH PASS FILTER IT!!!! This gets rid of the drift and makes the data MEANINGFUL!!!

To make a highpass or lowpass filter, type in FDATool in matlab.. then choose what you want to create. Once you build your filter, go to Edit-->Convert to Singleton!! Then File-->Generate m file to save it. To use it, follow the code below:

filterlow = lowpassfilter_1000Hz; %load low pass filter
Blow = filterlow.Numerator;
Alow = filterlow.Denominator;
data_filtered = filtfilt(Blow,Alow,data); % apply the lowpass filter.

Also, when writing reports its important that I specify which DATA TYPE I am going to use... periodic? random? transient? This matters because it will determine whether I use regular auto spectrum, PSDs, or ESDs.