[SAC-HELP] question about rdseed and transfer command.

[Sheila Peacock]

Dear Yueling Jing,

You do not need to worry about the messages from SAC, I think.
RDSEED has scaled the "constant" of your poles-and-zeros to
incorporate the "sensitivity" into it, so you do not need
a separate calibration factor ("calib"),  i.e.

constant, 6.941478e17 is equal to

A0 normalisation factor 5.71508e8 x sensitivity 1.21459e9 m/s/digital count

and the A0 normalisation factor was calculated on the
assumption that the calibration period (calper) was one second
(I have checked this with my program that finds the ratio of the
polynomials).

You can check that the calibration period really is one second
by sending for the data sheet for the seismometer from Guralp.
Send an email to caldoc at guralp.com with the serial number
of the seismometer in the header.  You should receive the data
sheet as a Microsoft Word document automatically.

The calibration factor "calib", in case you need it for other
purposes, is given by 1/(sensitivity in m/s * 2pi), but in
metres/count (so multiply by 10^9 if you need it in nanometres/count).
I make yours 1.310359e-10 metres/count.  If you want to check
that the value is correct, you need to get the digitiser data
sheet as well as the seismometer data sheet.  If it is a Guralp
digitiser then you can obtain this from caldoc at guralp.com
by putting the serial number of the digitiser on to the subject
line of the email (but beware that the resulting Microsoft Word
file will not display the values properly in OpenOffice, only in
genuine Microsoft Word).

Guralp seismometer data sheets give poles and zeros in terms of
hertz not radians, and in terms of velocity not displacement,
so you will find that there are only two zeros, not three, in
the data sheet for the seismometer, and
the poles need to be multiplied by 2pi/calper to match the
ones reported by rdseed.

Regards,
Sheila Peacock.

On 11/21/2011 07:52 AM, Yueling Jing wrote:

> Hi,
>
> Recently, I transferred velociy record SEED file to SAC file by rdseed,
>
> First, I use the command:
>
> "rdseed -f 200805120628045.SC.SEED -R -d -o -p 1"
>
> so the Poles and Zeros file are outputed,
>
> such as: SAC_PZs_SC_ZJG_BHZ_00_2007.182.00.00.00.0000_2009.182.24.60.60.99999
>
> *Can I specify the file name without the last part of number?* such as “SAC_PZs_SC_ZJG_BHZ_” .
> Second, I need to remove the instrument response of the data.
> *Can I use the transfer command as:*
> "r 2008*ZJG*BHZ*SAC"
>
> "Transfer from polezero subtype SAC_PZs_SC_ZJG_BHZ_00_2007.182.00.00.00.0000_2009.182.24.60.60.99999 to VEL"
>
> As a result, the output on the terminal is :
> **********************************
>
> Extracting polezero response for ZJG, BHZ...
>
> Station (ZJG), Channel (BHZ)
>
> Calper is not available. Cannot tell if response is normalized, so transfer function will be used without scaling.
>
> Calib is not available. Cannot tell if scale factor has been applied on input, so transfer function will be used without scaling.
>
> Waveform multiplied by 1.000000 after deconvolution.
>
> **********************************
>
> The details of SAC_PZs_SC_ZJG_BHZ_00_2007.182.00.00.00.0000_2009.182.24.60.60.99999 is as follow:
>
> * **********************************
>
> * NETWORK(KNETWK): SC
>
> * STATION(KSTNM): ZJG
>
> * LOCATION(KHOLE): 00
>
> * CHANNEL(KCMPNM): BHZ
>
> * CREATED: 2011-11-21T06:54:02
>
> * START: 2007-07-01T00:00:00
>
> * END: 2009-07-02T01:01:00
>
> * DESCRIPTION: Jiangyouzhongjiagou,Sichuan Province
>
> * LATITUDE: 31.792500
>
> * LONGITUDE: 104.672900
>
> * ELEVATION: 612.0
>
> * DEPTH: 0.0
>
> * DIP: 0.0
>
> * AZIMUTH: 0.0
>
> * SAMPLE RATE: 100.0
>
> * INPUT UNIT: M
>
> * OUTPUT UNIT: COUNTS
>
> * INSTTYPE: Guralp CMG-3ESPC Seismometer
>
> * INSTGAIN: 1.929980e+03 (M/S)
>
> * COMMENT: N/A
>
> * SENSITIVITY: 1.214590e+09 (M/S)
>
> * A0: 5.715080e+08
>
> * **********************************
>
> ZEROS3
>
> +0.000000e+00+0.000000e+00
>
> +0.000000e+00+0.000000e+00
>
> +0.000000e+00+0.000000e+00
>
> POLES5
>
> -7.397840e-02+7.397840e-02
>
> -7.397840e-02-7.397840e-02
>
> -1.004800e+03+0.000000e+00
>
> -5.024000e+02+0.000000e+00
>
> -1.130400e+03+0.000000e+00
>
> CONSTANT+6.941478e+17
> Thanks.
> Yueling
>
>
>
> _______________________________________________
> sac-help mailing list
> sac-help at iris.washington.edu
> http://www.iris.washington.edu/mailman/listinfo/sac-help