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Wed Dec 3 19:21:09 2008
I looked at the Ranger signals.
Somehow it has a relative transfer function of 'f' between it and the Guralp.
Ranger i.e. ------ ~ f Guralp
which is strange since according to their manuals, they should both be giving us a voltage output which is proportional
to velocity. I checked that the Ranger only has a load resistor and then an SR560 low pass at 300 Hz. Jenne assures
me that the Guralp breakout box shouldn't have any poles either (to be double checked). Its a mystery.
We made sure that the SR560 now is
DC coupled, G = 100, & 1-pole low pass at 300 Hz
. I moved it over next to the Guralp
(went through the mass recentering procedure after forgetting to lock it before moving). It is behaving as it was
Attached is a 2 page PDF of the comparisons. The 'MC1' channels are Guralp and 'MC2' is Ranger.
The second attachment compares our seismometers (in counts) with the LHO Guralp seismometers. There's no high frequency
rolloff there like what we see here so I bet a dollar that there's a pole in the Guralp box somewhere.