Updated: On Thursday/Friday (sorry for late elog) I was messing with Eric's Wilcoxon 731A accelerometer huddle test data that was taken without the box and cables being adjusted properly. Anyways, I performed the three cornered hat analysis as he had done but I also performed a six cornered hat method as well instead of permuting around in pairs of three accelerometers. The following plots of the ASD's show the results,
It is interesting to note the improvement at low frequencies when six accelerometers are used instead of six while at higher frequencies we can clearly see how the results are worst than the three hat results.
I decided to take a mean of all six accelerometers measured ground signal as well as that for their computed selfnoises, this is plotted below,
Notice the obvious improvement along the entire frequency band of the measurements when all accelerometers are used in the data analysis.
I also performed some Wiener filtering of this data. There was an obvious improvement in the results,
The mean of the signals is also plotted below, just as I did with the cornered hat methods,
I also compared the mean self noise of the accelerometers against the manufacturers calculated selfnoise that Rana put up on Github. Both methods are compared against what the manufacturer claims,
As expected the measured noise curves of the Wilcoxon is not as good as what the manufactures stated. This should improve once we redo the huddle test with a better experimental setup. We have some pretty interesting results with the six cornered hat method at around 5 Hz, it is surprisingly accurate given how rough the calculations seemed to be.
I have attached my code for reference: code_accel.zipselfnoise_allsix.png
SEE attachments for better plots of the six accelerometers... |