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Entry  Fri Jul 17 02:46:07 2015, Ignacio, Update, General, New huddle test data for Wilcoxon 731A results 6x
    Reply  Tue Jul 21 05:17:09 2015, Ignacio, Update, General, More clear accelerometer huddle tests results new_data.pngnew_data.pngold_data_1.pngold_data_1.pngold_data_2.png
       Reply  Thu Jul 23 21:12:14 2015, Ignacio, Update, General, Newer accelerometer huddle test data + detrending old_data_1.pngold_data_2.pngnew_data.pngsix_old_data.png
          Reply  Tue Jul 28 09:31:35 2015, Ignacio, Update, General, Newest accelerometer huddle test selfnoise_allsix_miso_newest.png
Message ID: 11442     Entry time: Thu Jul 23 21:12:14 2015     In reply to: 11432     Reply to this: 11450
Author: Ignacio 
Type: Update 
Category: General 
Subject: Newer accelerometer huddle test data + detrending 

In the last post concerning the self noise of the accelerometers, I mentioned the differences between the two data sets I was playing with. In order to give a more concrete analysis of the accelerometers self noise, we came to the conclusion that data taking time should be the same.

The plots below show the analysis for the following two datasets:

Old Data:  6 accelerometers, no cables clamped, no box, 55 mins worth of data.

Newer data: 3 accelerometers, cables clamped, foam box put on placed and completely sealed, 57.66 mins worth of data, (we had 20 mins of data in the previous data set).

Filter parameters were kept the same in all calculations, the only change that was added to the analysis was the detrending of the signals using the detrend function on Matlab, this improved the results as the plots show. I also plotted the error bars for the Wiener filtered result for reference as well as the manufactures claimed self noise.

   

After detrending the data and taking a longer dataset we can see the improvement brought upon by the foam box in the low frequency band of 0.5 - 10 Hz, as shown in the bottom left plot. There is a lot of noise that needs to be cancelled out from 10 Hz and on, which brings to our attention the plot on the bottom right corner. This plot uses the old data but uses all six accelerometers as witnesses, it also improved overall after having detrended the data, but what is peculiar about this plot is the fact that it manages to mitigate the higher frequency 10 - ~100 Hz band noise. 

 

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