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Entry  Fri Feb 19 15:12:38 2016, Koji, Summary, PEM, Guralp Health Check Guralp_Raw_PSD.pdflow_vel_comparison.pdfGuralp_TF.pdf
    Reply  Wed Mar 23 15:23:12 2016, Steve, Summary, PEM, Guralps as connected GUR_A.jpgGUR_B.jpgGUR_Interface_Box.jpg
       Reply  Thu Mar 24 08:20:52 2016, Steve, Update, PEM, Guralp-A calibration sheet 
       Reply  Fri Mar 25 19:17:28 2016, Nikhil, Update, PEM, Guralp Seismometers 16x
          Reply  Fri Mar 25 23:54:04 2016, rana, Update, PEM, Guralp Seismometers 
       Reply  Wed Aug 3 14:52:37 2016, Steve, Summary, PEM, Guralps as connected 
          Reply  Tue Aug 9 13:53:57 2016, babbott, Update, SEI, long Guralp EX cable repaired on the D-sub side 
             Reply  Tue Aug 9 19:35:49 2016, rana, Update, SEI, both Guralp seismometers are functioning and being acquired 1goodday.png
                Reply  Wed Aug 10 10:32:44 2016, Steve, Update, SEI, working Guralps as they are 6x
                   Reply  Fri Aug 12 14:37:34 2016, Steve, Update, SEI, working seismometers as they are eq_2.1m_Geysers_CA.pngeq2.1m_GeysersCA.pngoscillations.png
Message ID: 12000     Entry time: Fri Feb 19 15:12:38 2016     Reply to this: 12044
Author: Koji 
Type: Summary 
Category: PEM 
Subject: Guralp Health Check 

I measured the guralp raw outputs and the TFs using the handheld unit and an FFT analyzer.

[Setup]

The handheld unit was connected to each guralp with the same cable which is confirmed t be functional with the Yend Guralp.

The signal for Z, N, and E directions are obtained from the banana connectors on the handheld unit. Each direction has mass, low gain velocity, and high gain velocity output. The PSDs of the signals were measured with an FFT analyzer. The transfer function from the mass signal to the low/high gain signals were also measured for each direction.

The adjustment screw for the E output of the Xend does not work. I had to tilt the Xend Guralp using the leg screws to bring the E signal to zero.

[Result]

Attachment 1: Raw voltage PSD for all outputs
Attachment 2: Comparison of the low gain vel outputs

- All of the mass output show similar PSDs.
- Low gain velocity outputs shows somewhat similar levels. I still need to check if the output is really the ground velocity or not.
- High gain velocity outputs are either not high gain, broken, or not implemented.

- We need to calibrate the low gain output using signal injection, huddle test, or something else.

Attachment 3: TFs between each mass output and the low or high gain outputs

- TFs between the mass signal and the low vel signals show the similar transfer functions between the channels.
- The high gain outputs show low or no transfer function with regard to the mass signals.
 

Attachment 1: Guralp_Raw_PSD.pdf  189 kB  | Show | Hide all | Show all
Attachment 2: low_vel_comparison.pdf  55 kB  | Hide | Hide all | Show all
low_vel_comparison.pdf
Attachment 3: Guralp_TF.pdf  144 kB  | Hide | Hide all | Show all
Guralp_TF.pdf
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