Thread: Fwd: printed comment in transfer command

Sheila,

Thanks for your note.

At various times, it appears there has been some "optional" scaling within
SAC. In a 1997 message from Peter Goldstein, "The default for scale is
off (i.e., we don't multiply by calib anymore)." I think your colleague's
memory may have been for versions of SAC2000 for which "calib" was used to
rescale data.

There is a header variable named SCALE that (like EVDP) "is not currently
used." At the moment, waveforms produced by RDSEED have a value for SCALE
that is "B058F04 Sensitivity:" in the RESP file but is not used in SAC, so
far as I can tell. in my SAC e-mail archives, I find a message from
George H in 1991 in which he talks about using the unused SCALE flag in
the SAC header for instrument-correction stuff we were working on at that
time. "I changed the CDSEIS code to include the digital sensitivity (aka
gain) of each component as the SCALE variable in the header. As far as I
can tell, SAC doesn't use the value, but it will preserve it in the
header. I've not changed the value of the normalization constant in the
poles and zeroes description, however. So, after you do your transfer
command to remove the instrument response, you can say 'mul &n,SCALE&' to
change the amplitude to some length unit."

On Mon, 25 Jul 2011, Sheila Peacock wrote:

My colleague adds that the current IRIS-released version, 101.4, also
behaves this way. S.

-------- Original Message --------
Subject: [SAC-HELP] Fwd: Re: Fwd: printed comment in transfer command
Date: Mon, 25 Jul 2011 08:31:54 +0100
From: Sheila Peacock <sheila<at>blacknest.gov.uk>
Organisation: AWE Blacknest
To: sac-help<at>iris.washington.edu <sac-help<at>iris.washington.edu>

Dear Arthur and All,

I got this from my colleague who has been using SAC for a
long time.

Sheila Peacock.

-------- Original Message --------
Subject: Re: Fwd: [SAC-HELP] printed comment in transfer command
Date: Mon, 25 Jul 2011 08:27:30 +0100


Sheila,

this has probably been answered already.

The value is not always "1.0000". On older versions of SAC, if you apply
"transfer" to multiple waveforms simultaneously, then all but the first
waveform are multiplied by the "scale" value in the sac header. I always
assumed this was a bug or half-implemented feature so I always tried to
avoid it!


Sheila Peacock wrote:

-------- Original Message --------
Subject: [SAC-HELP] printed comment in transfer command
Date: Wed, 6 Jul 2011 19:34:49 -0400 (EDT)
From: Arthur Snoke <snoke<at>vt.edu>
To: SAC-help Listserv <sac-help<at>iris.washington.edu>

For all transfer commands, there is a line printed to the screen:

Waveform multiplied by 1.000000 after deconvolution.

So far as I can tell it, this line serves no purpose. If any of you know
a reason to keep this printed output, please let me know.