[Homer-users] HOMer version 3.1 official release

[David Boas]

Ted,
You only need to keep the I and Q for the low pass filter.  Once you perform
the low pass filter you can then just work with the amplitude.

What I don't remember is whether or not the low pass filter is performed
before or after the logarithm.  If before, then you take the low-pass
filter, convert from I and Q to amplitude, and then proceed. If you take the
logarithm before the low-pass filter, then maybe we should consider taking
the logarithm after the low-pass filter.  I can't see any obvious problems
with that.

I just checked the code and it seems the log is done before the low-pass
filter.  I don't see any problem with moving the log to after the low-pass.

David






> -----Original Message-----
> From: homer-users-bounces at nmr.mgh.harvard.edu [mailto:homer-users-
> bounces at nmr.mgh.harvard.edu] On Behalf Of Ted Huppert
> Sent: Wednesday, March 17, 2004 5:10 PM
> To: Maria Angela Franceschini
> Cc: Homer-users at nmr.mgh.harvard.edu; sdiamond at nmr.mgh.harvard.edu;
> jstott at nmr.mgh.harvard.edu
> Subject: Re: [Homer-users] HOMer version 3.1 official release
> 
> AGHHHH!  That's totally my fault.  I had made the I and Q "fix" to HOMer
> to preserve the imaginary component in the processing up until displaying
> the data as suggested by Jon-  Stupidly, I took the absolute value to
> make it all real right before displaying.  Its a
> real easy fix that I post tonight (just fixed it on mine and it y'all look
> in the code its obvious -in the HOMerFilt.m file under pushbutton_
> update_callback   - the last few lines or so-  )
> 
> How can I find the magnitude of a complex number and preserve the sign?  I
> guess I can just say "real()" but that won't pick up the phase info (so I
> might as well not had it as a complex number).
> 
> how about:  sign(real(x))*abs(x)   -or does that screw up the sign of the
> phase correction???
> 
> BTW- that chnge was made in the code just last week- all older versions
> are fine.
> 
> Sorry about that-
> 
> Ted
> 
> 
> 
> 
> On Wed, 17 Mar 2004, Maria Angela Franceschini wrote:
> 
> > Hi all,
> > I was trying the new version of homer, and there is an error (probably
> > trivial). The DOD is calculated from an absolute value instead of been
> > normalized to zero. I went back to homer version 2 (before Marge) and
> things
> > are fine.
> > mari
> >
> 
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