Eric downloaded MC2 to MCL transfer function data (H) as well as its inverse, MCL to MC2 (Hinv). He also downloaded new MCL and MC2 data.
I used vectfit to fit the MC2 to MCL transfer function,
The ZPK parameters for this fit were,
Zeros 1278.36719876674 + 0.00000000000000i
-100.753249679343 + 0.00000000000000i
-18.6014192997845 + 13.0294910760217i
-18.6014192997845 - 13.0294910760217i
Poles -1.11035771175328 + 7.03549674098987i
-1.11035771175328 - 7.03549674098987i
-18.8655320274072 + 0.00000000000000i
-690.294337433234 + 0.00000000000000i
Gain 0.00207206036014220
Using the above vectfit model, I filtered the raw MC2 signal to get 'MCL'. The PSD's of the raw MCL data and the filtered MC2 result is shown below,
The lack of accuracy of the transfer function at replicating MCL at frequencies lower than 0.7Hz is expected, the vectfit model I generated fails to follow accurately the raw transfer function data. My question: Does it matter? My guess: Probably not. In order to mitigate seismic noise from the mode cleaner we are mainly concerened with the 1-3 Hz region.
I also used vectfit to fit the transfer function for MCL to MC2,
This one was harder to fit accurately for some reason, I could do it with four pairs of zeros and poles but it took some preweighting.
The ZPK parameters for the above fit were,
Zeros 0.173068278283995 + 0.00000000000000i
0.995140531040529 + 0.0268079821980457i
0.995140531040529 - 0.0268079821980457i
0.894476816129099 + 0.00000000000000i
Poles -19.9566906920707 + 18.0649464375308i
-19.9566906920707 - 18.0649464375308i
-109.275971483008 + 0.00000000000000i
-1791.88947801703 + 0.00000000000000i
Gain 1237.46417532120
Similarly, using this ZPK model, I filtered the MCL signal to get 'MC2'. I plotted the PSD for the MC2 signal and the filtered MCL to get,
Again, the lack of accuracy of the filtered MC2 at replicating MCL below 0.7 Hz and above 12 Hz is due to the inverse transfer function failing to converge in these ranges. |