The NCD Oscillatory Noise Cut is based on logged NCD (signal is negative) signals and is designed to remove oscillatory noise events. This cut is coded as a SNOMAN hard-wired cut "flt_NcdOscNoise_cut.for". The parameter for this cut are found in "filter_flth.dat" :
*DO FLTH 32 -i(30I -I) #. FLTH: NCD OSC noise Cut #. 19750101 0 20380517 03331900 6*0 #. Standard Database Header 19750101 0 20380517 03331900 16*0 #. 5 #. threshold on number of oscillations 5 #. Upper boundary of oscillation 3 #. Lower boundary of oscillation
The threhold for this cut is based on the AVERAGE and RMS value calculated from the last 2000 bins in the scope trace. In case that RMS is larger than 5 (or the second parameter in FLTH), it is reset to 5 (or the second parameter in FLTH). In case that RMS is smaller than 3 (or the third parameter in FLTH), it is reset to 3 (or the third parameter in FLTH). We count how many times the trace goes below AVERAGE-RMS and then goes above AVERAGE+3RMS. If this happens more than 5 (or the first parameter in FLTH), this event is determined to be an oscillatory noise event.
To use this cut, one can put a call flt($ncdoscnoise_cut) in the programmable event loop. The cut returns "trre" if the event is a good event.