Thread: overall sensivity computation

Started: 2021-06-24 12:28:25
Last activity: 2021-07-06 09:58:49
Topics: PDCC
laure.duboeuf@realtimeseismic.com
2021-06-24 12:28:25
Dear Sir or Madam,



I currently work on removing instrument response on a 1s seismometer.

I generate a dataless using PDCC software.



The overall sensitivity is of 468170 000.

However, the seismometer gain is of 400 and the digitizer of 1677720.

According to the definition given in the resp file manual, the overall
sensitivity is the product of all gains.

Here, 400 * 1677720 = 671 088 000



671 088 000 / 468 170 000 = ~1.43

So I have a ~1.43 factor (sqrt(2) between the overall sensitivity given by
PDCC and the sensitivity obtained from the product of all gains.



Do you have any idea to explain this factor?



My best



Laure Duboeuf



--------------------------------------------------------------------------

Dr. Laure Duboeuf, Senior Geophysicist

Microseismicity
RealTimeSeismic (RTS)

Phone: +33 (0)6 33 20 14 59



http://www.realtimeseismic.com/ www.realtimeseismic.com

Technopole Hélioparc

2, avenue du Président Pierre Angot
CS 8011 64053 PAU
FRANCE





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Attachments
  • Mary Templeton
    2021-07-06 09:58:49
    Good morning Laure,

    Thank you for your email.

    Each stage gain is associated with a specific frequency in the amplitude-frequency
    curve. Each individual stage can specify its gain at a different frequency and PDCC
    calculates the overall sensitivity (stage 0 in dataless SEED) at the sensitivity of the ADC
    stage (stage 3) by default. This value is typically 0.05 Hz, which is great for a broadband
    seismometer, but is not within the passband of a 1 Hz sensor. To get adjust the response
    for short-period stations in PDCC, you’ll need to:

    1) edit the stage 0 Frequency of Sensitivity to equal that of your sensor stage
    2) select your channel in the left menu bar
    3) Select "Recalculate Sensitivity" from the Tools pulldown menu, and
    4) select “Launch”

    Calculating the sensitivity in the passband of the sensor (as well as the datalogger)
    should fix the discrepancy.

    cheers,
    Mary

    On Jun 30, 2021, at 4:56 PM, laure.duboeuf<at>realtimeseismic.com (via IRIS) <pdcc-bounce<at>lists.ds.iris.edu> wrote:

    Dear Sir or Madam,

    I currently work on removing instrument response on a 1s seismometer.
    I generate a dataless using PDCC software.

    The overall sensitivity is of 468170 000.
    However, the seismometer gain is of 400 and the digitizer of 1677720.
    According to the definition given in the resp file manual, the overall sensitivity is the product of all gains.
    Here, 400 * 1677720 = 671 088 000

    671 088 000 / 468 170 000 = ~1.43
    So I have a ~1.43 factor (sqrt(2) between the overall sensitivity given by PDCC and the sensitivity obtained from the product of all gains.

    Do you have any idea to explain this factor?

    My best

    Laure Duboeuf

    --------------------------------------------------------------------------
    Dr. Laure Duboeuf, Senior Geophysicist
    Microseismicity
    RealTimeSeismic (RTS)
    Phone: +33 (0)6 33 20 14 59
    <image001.png>
    www.realtimeseismic.com
    Technopole Hélioparc
    2, avenue du Président Pierre Angot
    CS 8011 64053 PAU
    FRANCE


    Garanti sans virus. www.avast.com

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