40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Thu Jul 26 17:39:49 2012, Den, Update, digital noise, biquad key is working df2_bqf.pngdf2_bqf_spec.pngiir_psd_notch.pngiir_time_notch.png
    Reply  Thu Jul 26 21:31:44 2012, Den, Update, digital noise, online biquad works  df2_bqf_lp.pngdf2_bqf_lp_spec.png
    Reply  Fri Jul 27 14:30:49 2012, Jamie, Update, digital noise, biquad key is working 
       Reply  Mon Jul 30 14:24:25 2012, Den, Update, digital noise, biquad key is working lnf.png
Message ID: 7041     Entry time: Thu Jul 26 17:39:49 2012     Reply to this: 7042   7045
Author: Den 
Type: Update 
Category: digital noise 
Subject: biquad key is working 

 I've filtered a 1 Hz sin wave excitation with a notch filter inside c1sus and c1rfm models. The biquad key is switched on in the last one, c1sus uses DF2. The results are indeed different.

df2_bqf.png    df2_bqf_spec.png

Still I do not like huge (2n+1) harmonics in the output of the biquad filter, I do not get them in the simulations. They are absent in the time series as well. So this is not a psd-estimation effect.

iir_time_notch.pngiir_psd_notch.png

 

ELOG V3.1.3-