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Entry  Tue May 19 19:24:30 2015, rana, Update, PEM, Seismic BLRMS filters BLRMS_BP.pdfBLRMS_imp.pdf
    Reply  Mon Sep 7 19:46:46 2015, rana, Update, PEM, Seismic BLRMS filters T240_150907.png
       Reply  Wed Sep 9 15:45:11 2015, ericq, Update, PEM, Inverted STS filters in C1OAF 
Message ID: 11316     Entry time: Tue May 19 19:24:30 2015     Reply to this: 11582
Author: rana 
Type: Update 
Category: PEM 
Subject: Seismic BLRMS filters 

I was wondering about the design of the BLRMS fitlers for the seismic channels since the STS ones seem to have so little gain compared to the Guralps.

Here are some plots of the Bode magnitude and impulse responses of the bandpass filters (before the low passing). There's a bunch of entries from Masha on this from her SURF summer. Can anyone comment on why they are all so different?

One of the old Masha entries speaks of designing the lowpass filter in an intelligent way: by adjusting the filter order until the power in the stopband is less than 1% of the power in the passband. Seems like we could do that for bandpass too. For now I have made the names reasonable and changed all of the BP filters to 4th order Butterworth.

Also, it turns out that the Vel2Vel (gain ~0.02) filters were mistakenly on in the STS BP filter banks. The GUR inputs have a gain to scale the counts to velocity, but the STS seem to already be in microns/sec (where is this gain?) so I turned off and deleted the Vel2Vel filters; in any case the gain should not be done seperately in each BP bank, but altogether before the BP filtering.

Attachment 1: BLRMS_BP.pdf  18 kB  | Hide | Hide all
BLRMS_BP.pdf
Attachment 2: BLRMS_imp.pdf  20 kB  | Hide | Hide all
BLRMS_imp.pdf
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