Thread: GDSN (BB) FREQLIMITS in TRANSFER command

Started: 2015-05-07 21:48:22
Last activity: 2015-05-08 02:49:24
Topics: SAC Help
E. Tsakiroudi
2015-05-07 21:48:22
Hi there!
For GDSN BH? and LH? data, which are the best values for 'freqlimits' f1, f2, f3, f4 in the TRANSFER command, in order to safely remove the instrument?
Do these frequency values represent the flat part of the instrument's response?
Are these values different for each instrument of the GDSN network?
Which values would you suggest to be used for all GDSN instruments together?


  • Milton Plasencia
    2015-05-08 02:49:24
    Hi,

    see inline,

    M.

    On May 7, 2015, at 16:48, Eva Tsakiroudi <evatsakir<at>yahoo.com> wrote:

    Hi there!

    For GDSN BH? and LH? data, which are the best values for 'freqlimits' f1, f2, f3, f4 in the TRANSFER command, in order to safely remove the instrument?
    Depend of instrument band frequency and also the sample rate, in this case BH (frequency are from >=10 to <80 Hz) if BH=20 sps you can filtering up to
    Nyquist frequency, so 10 Hz maximum in high frequency (low pass filter), for low frequency depend of the corner frequency of the sensor (high pass filter).
    In short f1 and f2 correspond to the hp filter and f3 and f4 to the lp filter.

    Do these frequency values represent the flat part of the instrument's response?
    Yes, but i suggest flat from f2 up to f3. See the transfer help command in particular the FREQLIMITS part.

    Are these values different for each instrument of the GDSN network?
    Yes, depend of sensor and digitizers.

    Which values would you suggest to be used for all GDSN instruments together?
    I think you can take the lower band of the all instruments, so you are always for in flat part, but perhaps if you have short period and
    long period instruments you can lost important information.



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