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<DIV dir=ltr align=left><SPAN class=125051206-13042009></SPAN><STRONG><FONT
face="Courier New">H<SPAN
class=125051206-13042009>ello,</SPAN></FONT></STRONG></DIV>
<DIV><STRONG><FONT face="Courier New"><SPAN
class=125051206-13042009></SPAN></FONT></STRONG> </DIV>
<DIV><STRONG><FONT face="Courier New"><SPAN class=125051206-13042009>Reftek 130
has 24 bit digitizer. and the min and max count values are +-2^(24-1) =
6291456 count for +- 20V </SPAN></FONT></STRONG></DIV>
<DIV><STRONG><FONT face="Courier New"><SPAN
class=125051206-13042009>20/(2*6291456) =
1.5895microVolt/count.</SPAN></FONT></STRONG></DIV>
<DIV><STRONG><FONT face="Courier New"><SPAN
class=125051206-13042009></SPAN></FONT></STRONG> </DIV>
<DIV><STRONG><FONT face="Courier New"><SPAN class=125051206-13042009>We use
ref2segy and seg2sac programs to convert the files.</SPAN></FONT></STRONG></DIV>
<DIV><STRONG><FONT face="Courier New"><SPAN class=125051206-13042009>segy2sac
(without -g parameter) removes the Reftek gain and its output is in Volts.
</SPAN></FONT></STRONG></DIV>
<DIV><STRONG><FONT face="Courier New"></FONT></STRONG><STRONG><FONT
face="Courier New"></FONT></STRONG> </DIV>
<DIV><STRONG><FONT face="Courier New"></FONT></STRONG> </DIV>
<DIV><SPAN class=125051206-13042009><FONT face="Courier New"><STRONG>best
regars</STRONG></FONT></SPAN></DIV>
<DIV><SPAN class=125051206-13042009><STRONG><FONT
face="Courier New">Onur</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=125051206-13042009></SPAN> </DIV>
<DIV><SPAN class=125051206-13042009></SPAN><SPAN class=125051206-13042009><FONT
size=2> Dr. Onur TAN
|------------------------------------------------------------<BR> -------------
|<BR>| TÜBİTAK Marmara Araştırma Merkezi | TUBITAK Marmara Research
Center |<BR>| Yer ve Deniz Bilimleri
Enstitüsü | Earth and Marine Sciences Institute |<BR>| Gebze -
Kocaeli
| Gebze - Kocaeli -
TURKEY
|<BR> --------------------------------------------------------------------------</FONT>
</DIV></SPAN>
<DIV dir=ltr align=left><BR></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> sac-help-bounces@iris.washington.edu
[mailto:sac-help-bounces@iris.washington.edu] <B>On Behalf Of </B>Chad
Trabant<BR><B>Sent:</B> Friday, April 10, 2009 5:19 AM<BR><B>To:</B>
sac-help@iris.washington.edu<BR><B>Subject:</B> Re: [SAC-HELP] Calculating the
CONSTANT to use to remove instument response<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV><STRONG><FONT face="Courier New"></FONT></STRONG><BR></DIV>
<DIV>Melaku,</DIV>
<DIV><BR></DIV>
<DIV>I can't help you verify the RefTek gain value. If the equipment is
from the IRIS PASSCAL Instrument Center perhaps you can ask them for more
details of the digitizer. If the data was processed by PASSCAL you might
also have the data in SEED format in which case you can use the rdseed program
to create the SAC poles and zeroes file for you. If you have a manual or
any documentation for the digitizer it might be in there as well.</DIV>
<DIV><BR></DIV>
<DIV>Chad</DIV><BR>
<DIV>
<DIV>On Apr 9, 2009, at 5:46 PM, Melaku Ayenew wrote:</DIV><BR
class=Apple-interchange-newline>
<BLOCKQUOTE type="cite">Hi Chad,<BR>Thank you so much! It help me a
lot!<BR>One thing I am not sure about is the digitizer gain, I got this value
from IRIS, PASCAL, High Resolution Acquisition systems, under <BR>
<H3 style="FONT-WEIGHT: normal">Reftek R130 , 24 bit, 3 channel digitizer bit
weight 1.589e-6 volts @ X1<BR></H3>
<H3 style="FONT-WEIGHT: normal">gain.</H3>Thank you once
again.<BR><BR>Melaku<BR><BR>
<DIV class=gmail_quote>On Thu, Apr 9, 2009 at 5:28 PM, Chad <SPAN
dir=ltr><<A
href="mailto:chad@iris.washington.edu">chad@iris.washington.edu</A>></SPAN>
wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">
<DIV>
<DIV><BR></DIV>
<DIV>Hello Melaku,</DIV>
<DIV><BR></DIV>
<DIV>I am forwarding this to the sac-help list in the hopes that it may
garner the attention of more expertise.</DIV>
<DIV><BR></DIV>
<DIV>Your calculation of CONSTANT looks generally correct with the exception
of the 2*pi, it should not be included.</DIV>
<DIV><BR></DIV>
<DIV>A standard gain STS-2 should be nominally 1500 Volts/meters/second,
which needs to be scaled if you want nanometers. I have no idea what
the digitizer gain for a RefTek 130 is, but lets assume your
number is correct for now.</DIV>
<DIV><BR></DIV>
<DIV>CONSTANT = A0 * SensorGain * Digitizer Gain</DIV>
<DIV><BR></DIV>
<DIV>CONSTANT = 5.92e+07 * 1500 / 1.589e-06 = 5.588e+16 (so it
looks like 2*pi is not in there after all).</DIV>
<DIV><BR></DIV>
<DIV>That CONSTANT results in units of meters. So scale it by a factor
of 1e9 for nanometers = 5.588e25</DIV>
<DIV><BR></DIV>
<DIV>Hopefully someone more knowledgeable will correct any mistakes I've
made.</DIV>
<DIV><BR></DIV>
<DIV>On a slight related note, the poles and zeros you are using are the
"truncated"/"simplified" STS-2 response and not the STS-2 nominal responses
(you can access the nominal responses for each of 3 generations of STS-2
here: <A
href="http://www.iris.edu/NRL/sensors/streckeisen/streckeisen_sts2_sensors.html%29"
target=_blank>http://www.iris.edu/NRL/sensors/streckeisen/streckeisen_sts2_sensors.html)</A>.
This is not a critical problem unless you are working with high
frequency data, I have heard that it's not important below 35 Hz.</DIV>
<DIV><BR></DIV><FONT color=#888888>
<DIV>Chad</DIV></FONT>
<DIV>
<DIV></DIV>
<DIV class=h5>
<DIV><BR></DIV>
<DIV>
<DIV>On Apr 9, 2009, at 3:11 PM, Melaku Ayenew wrote:</DIV><BR>
<BLOCKQUOTE type="cite">Hello Chad,<BR>Thank you for your response <BR>I
am just starting to learn sac for my research, I was trying to remove
STS-2 broadband instrument and convolute the Wood-Anderson response. This
is the STS2.pz file I came up with would you check it for me
please<BR><BR>ZEROS 2 (rad/sec)<BR>0.000
0.000<BR>0.000 0.000<BR><BR>POLES 5
(rad/sec)<BR><BR>-0.03701
0.03701<BR>-0.03701
-0.03701<BR>-251.3
0.0000<BR>-131.0
467.30<BR>-131.0
-467.30<BR><BR>CONSTANT 5.5884E+16<BR><BR>This is how I calculate
the the Constant <BR>CONSTANT=A0 X SensorGain X Digitizer Gain X
2*pi<BR>Where A0 is normalization factor =5.92 E+07<BR>The digitizer is
REF TEC 130 data logger with bit weight 1.589E-06volts which I figure the
digitizer gain would be 1/1.589 E-06 ( I am not sure about this
step)<BR><BR>And from SAC>transfer from polezero subtype STS2.pz to
WA<BR><BR>when I plot this I got a waveform with amplitude in the
order of 10E-4 nm (transfer returns values in nm)<BR><BR>I really
appreciate your help.<BR>Thank you in advance.!!<BR><BR><BR><BR>Melaku
Bogale<BR>New Mexico State University<BR>Department of Physics<BR>Las
Cruces NM 88003-8001<BR><BR><BR> <BR><BR>
<DIV class=gmail_quote>On Wed, Apr 8, 2009 at 10:13 PM, Chad Trabant <SPAN
dir=ltr><<A href="mailto:chad@iris.washington.edu"
target=_blank>chad@iris.washington.edu</A>></SPAN> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid"><BR>Hello
Melaku Bogale,<BR><BR>You need to know the total sensitivity of the
digitizer, this is the value which relates digital counts to ground
units. The poles and zeros only represent the sensor. The
CONSTANT in the SAC poles and zeros file should be the total sensitivity
multiplied by the normalization factor for the poles and zeroes.
The value for CONSTANT depends on the units desired
also.<BR><BR>Chad<BR>IRIS DMC
<DIV>
<DIV></DIV>
<DIV><BR><BR>On Apr 8, 2009, at 3:50 PM, Melaku Ayenew
wrote:<BR><BR></DIV></DIV>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">
<DIV>
<DIV></DIV>
<DIV>Hi All,<BR>I am trying to remove instrument responses from STS_2,
CMG3T. CMG_ES broadband instruments. I got the poles and zeros from
IRIS Pascal Instrumentation. But I have difficulty figuring out what
constant I should use in the *.pz file that has to read by the SAC
TRANSFER command. For example, I was trying to synthesis a WA
seismogram by removing the STS_2 response and convoulating the WA
response. I used a constant of 1 in this calcultion. The synthesis
seismogrm looks good but the displacemnt values don't make sense (they
are several hunderd meters). I understand it is because of the
CONSTANT=1 I put. My Question is How can I calculate the correct
CONSTANT that I need to put with the zeros and poles in the SAC *.pz
file. The IRIS PASCAL instrumentation page gives the zeros and poles
and a normalization factor.<BR>I greatly appreciate your help in this
matter.<BR><BR>Melaku Bogale<BR>New Mexico State
University<BR>Department of Physics<BR>Las Cruces NM
88003-8001<BR></DIV></DIV>_______________________________________________<BR>sac-help
mailing list<BR><A href="mailto:sac-help@iris.washington.edu"
target=_blank>sac-help@iris.washington.edu</A><BR><A
href="http://www.iris.washington.edu/mailman/listinfo/sac-help"
target=_blank>http://www.iris.washington.edu/mailman/listinfo/sac-help</A><BR></BLOCKQUOTE><BR></BLOCKQUOTE></DIV><BR></BLOCKQUOTE></DIV><BR></DIV></DIV></DIV></BLOCKQUOTE></DIV><BR></BLOCKQUOTE></DIV><BR></BODY></HTML>