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Entry  Wed Oct 5 22:59:11 2011, Koji, Frank, Notes, Seismic, mechanical properties of new stack  
    Reply  Thu Oct 6 03:37:44 2011, Koji, Notes, Seismic, Modeling of the vertical isolation of the stack vertical_isolation.pdfvertical_isolation.zipvertical_isolation_plot.pdf
       Reply  Tue Oct 25 22:03:32 2011, frank, tara, Notes, Seismic, Modeling of the vertical isolation of the stack nb.png
          Reply  Wed Oct 26 18:05:49 2011, frank, tara, Notes, Seismic, Modeling of the vertical isolation of the stack 6x
             Reply  Thu Oct 27 20:45:58 2011, frank, tara, Notes, Seismic, ring down measurement for rubber spring fit4.pngfit1.pngcomparefit.pnghist.png
                Reply  Thu Nov 3 01:55:03 2011, Frank, Notes, Seismic, ring down measurement for rubber spring 
             Reply  Fri Oct 28 14:04:22 2011, frank, tara, Notes, NoiseBudget, Noise budget for unfloated table beat_27.pngbeat_27.fig
                Reply  Wed Nov 16 19:11:38 2011, tara, Notes, NoiseBudget, seimic coupling to beat noise 
                   Reply  Thu Nov 17 23:30:19 2011, tara, Notes, NoiseBudget, vertical seismic coupling to beat noise SETUP_2011_11_17.pngfreq_resp.pngfreq_resp.fig
                      Reply  Wed Nov 30 19:00:42 2011, tara, Notes, NoiseBudget, vertical seismic coupling to beat noise Seismic_resp.pngSeismic_resp.figSNR.png
Message ID: 735     Entry time: Thu Nov 17 23:30:19 2011     In reply to: 734     Reply to this: 741
Author: tara 
Type: Notes 
Category: NoiseBudget 
Subject: vertical seismic coupling to beat noise 

TFs between 1)vertical seismic and beat, 2) v seismic and ACAV feedback, and 3) v_seismic and TTFSS feedback are measured. The contribution from vertical seismic to beat signal is mostly from ACAV.

 ==Setup==

I used frequency response measurement (FFT1/FFT2) to measure frequency response [dB], phase [dB], and coherence between.

  • vertical seismic and beat, -> D/A
  • Actuator point for ACAV loop -> C/A
  • Fast Actuator point, RCAV loop ->B/A  (I used a T connector to pull the signal from feedback to NPRO)

The calibration for beat signal[D] is 7kHz/V, for ACAV actuator point [C] is 7kHz/V, for RCAV fast actuator [B] is 3.07 MHz/V, for accelerometer [A] is 1023mV/g (psl:716)

SETUP_2011_11_17.png

==result==

 1)calibrated signal, in the unit of Frequency noise in beat/ acceleration  [Hz/ (m/s^2) ]

freq_resp.png

fig1: calibrated frequency response, with 250 vector avg.

==comments==

  The plots show that the seismic contribution in the beat is mostly coupled through ACAV. RCAV is not sensitive to seismic at all, since the coherence is almost zero. We have to open the chamber and fix the ACAV's support.

Attachment 3: freq_resp.fig  85 kB  Uploaded Sat Nov 19 06:17:33 2011
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