<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Andrew,<div><br></div><div>What you are seeing is correct.</div><div><br></div><div>In previous versions of SAC, 101.3 and earlier:</div><div>If the station name (kstnm) is not defined, it would default to "sta"</div><div>If the channel name (kcmpnm) is not defined, it would default to "Q"</div><div>The stations and channel names were only changed on read. </div><div>It was added a long while ago to "Disallow undefined kstnm and kcmpnm".</div><div><br></div><div>We removed this in 101.4. It was considered to be confusing behavior.</div><div><div>From the HISTORY file:</div><div> * BUG FIX: Stations no longer named 'sta' and channels 'Q' by default</div></div><div><br></div><div>If you need this, or have scripts/programs that rely on it, you can change the header values to a something you expect.</div><div>SAC> ch kcmpnm Q</div><div>or if you know they are radial transverse, you could use</div><div>SAC> ch kcmpnm BHR </div><div><br></div><div>For your processing:</div><div>On the initial read, the fields kcmpnm for both files are probably set to BHN and BHE </div><div>The ROTATE command sets the kcmpnm fileds to undefined (-12345.0)</div><div>You write the files out. The kcmpnm is still set as "-12345.0"</div><div>You read the files back in. On this read the kcmpnm is set to "Q" as 101.3 did not allow a undefined kcmpnm field.</div><div><br></div><div><div>If this change caused havoc, we apologize.</div></div><div><br></div><div>I hope this helps.</div><div><br></div><div>Brian Savage</div><div><a href="mailto:savage@uri.edu">savage@uri.edu</a></div><div><br></div><div>Example run using 101.4:</div><div><br></div><div><div>SAC> fg seismo</div><div>SAC> ch cmpinc 90</div><div>SAC> ch cmpaz 0</div><div>SAC> ch kcmpnm BHN</div><div>SAC> w tmp.n</div><div>SAC> ch cmpaz 90</div><div>SAC> ch kcmpnm BHE</div><div>SAC> w tmp.e</div></div><div>SAC> read tmp.n tmp.e</div><div><div>SAC> lh cmpaz cmpinc az baz kcmpnm columns 2</div><div> </div><div> </div><div> FILE: tmp.n - 1</div><div> -----------</div><div><br></div><div> cmpaz = 0.000000e+00 cmpinc = 9.000000e+01</div><div> az = 8.814721e+01 baz = 2.718528e+02</div><div> kcmpnm = BHN</div><div> </div><div> FILE: tmp.e - 2</div><div> -----------</div><div><br></div><div> cmpaz = 9.000000e+01 cmpinc = 9.000000e+01</div><div> az = 8.814721e+01 baz = 2.718528e+02</div><div> kcmpnm = BHE</div><div>SAC> rotate</div><div>SAC> lh cmpaz cmpinc az baz kcmpnm columns 2</div><div> </div><div> </div><div> FILE: tmp.n - 1</div><div> -----------</div><div><br></div><div> cmpaz = 9.185278e+01 cmpinc = 9.000000e+01</div><div> az = 8.814721e+01 baz = 2.718528e+02</div><div> </div><div> FILE: tmp.e - 2</div><div> -----------</div><div><br></div><div> cmpaz = 1.818528e+02 cmpinc = 9.000000e+01</div><div> az = 8.814721e+01 baz = 2.718528e+02</div></div><div><div>SAC> evaluate ( ( &1,baz + 180 ) - &1,cmpaz )</div><div> 3.6000000e+02</div></div><div><br></div><div><br></div><div>On Jul 6, 2011, at 10:19 AM, Andrew Schaeffer wrote:</div><div><div><br class="Apple-interchange-newline"><blockquote type="cite">Hello,<div><br></div><div>I am trying to resolve a difference between the SAC versions 101.3b and 101.4.</div><div><br></div><div><u>In 101.3b</u>:</div><div>I am performing "rotate to gcp" on a north and east component seismogram, and writing out the radial and transverse components:</div>
<div><font class="Apple-style-span" face="'courier new', monospace">r s1.dn <a href="http://s1.de/">s1.de</a></font></div><div><font class="Apple-style-span" face="'courier new', monospace">rotate to gcp</font></div>
<div> ->If I list the header (lh) at this point, the KCMPNM header value is now empty (ie doesn't show up).</div><div><font class="Apple-style-span" face="'courier new', monospace">write s1.dr s1.dt</font></div>
<div><font class="Apple-style-span" face="'courier new', monospace">quit</font></div><div><br></div><div>If I start sac again, and read in the dr and dt components, they now have the KCMPNM header value, with "Q" for both components.</div>
<div><br></div><div>If I repeat the same procedure in 101.4, the KCMPNM header value remains empty, even after writing the seismograms and reloading them.</div><div>Can anyone confirm whether this is the expected behaviour (ie the difference between the two versions), or what their version is doing?</div>
<div><br></div><div>many thanks,</div><div>Andrew</div>
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