[Dsg-hallb_magnets] Filtered Torus Fast-Daq data

[Tyler Lemon]

Hello Ruben and Probir, 

A lowpass filter with cutoff frequency 50Hz was deployed to the Torus Fast-Daq cRIO. Attached are screenshots of the EPICS Live Fast-Daq screen from before and after the filter is applied. 

When the filter is applied, there appears to be an offset for scaled voltage taps. The offset seems to be about the signal average before the filter was applied (unfiltered average noted in attached "Unfiltered Voltage Tap Statistics 2017-01-23.JPG"). Some filtered signals also appear to oscillate in amplitude. Amplitude oscillations can be seen when comparing "01 Filtered Fast-Daq 2017-01-23.JPG" and "02 Filtered Fast-Daq 2017-01-23.JPG". The amplitude oscillations are probably due to frequency changes in the unfiltered noise, as the unfiltered signal's frequency determines the filtered signal's attenuation. 

Fast-Daq data was also recorded via EPICS during test with file names below: 
file name time length filter applied 
torus_20170123_141100.root 1 minute no filter 
torus_20170123_142200.root 1 minute lowpass filter, cutoff frequency 50Hz 
torus_20170123_142600.root 5 minutes lowpass filter, cutoff frequency 50Hz 

For now, the original Fast-Daq program without any filtering has been redeployed. 

If the filtered Fast-Daq program should be deployed for other tests or so anyone can see resulting signals for themselves, it can be done. 

Best regards, 
Tyler 

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