Bug 86659

Summary:	command line option, supress low frequency signal/noise
Product:	[Applications] kst	Reporter:	William Jones <wcjones>
Component:	general	Assignee:	kst
Status:	RESOLVED INTENTIONAL
Severity:	wishlist
Priority:	NOR
Version:	1.x
Target Milestone:	---
Platform:	Debian testing
OS:	Linux
Latest Commit:		Version Fixed In:

Description William Jones 2004-08-05 21:54:55 UTC

Version:           0.82 (using KDE 2.2.2)
Installed from:    Debian Package 4:2.2.2-13.woody.6 (3.0)
Compiler:          gcc version 2.95.4 20011002 (Debian prerelease)
OS:                Linux (i686) release 2.4.19-lac3

It would be really nice if there was a way to suppress low frequency noise (or signal, if one is so lucky) from a data vector.  This would be very helpful for visualizing small signals riding on large low frequency noise fluctuations. When viewing PSDs of real data, this option would obviate the frequent autoscaling problem, in which the interesting part of the spectrum is dwarfed by the noise at low frequencies.  

A command line option to implement the "Low Frequency Interference" subtraction would be very convenient.  The argument of the option could be the highpass edge in, say, units of the resolution element, or in Hz (if the sample rate is supplied as well).  For instance, the command line of this sort

kst -lfi 2 -r 200

would specify the sample rate (200 Hz), and the highpass edge of the filter required to overcome the low frequency noise in the data (2 Hz).

Thanks,

Bill

Comment 1 George Staikos 2004-08-05 22:00:13 UTC

On Thursday 05 August 2004 15:54, William Jones wrote:
> Version:           0.82 (using KDE 2.2.2)

   Wow that's old.  Time to upgrade your Kst. :)  
http://extragear.kde.org/apps/kst.php

> It would be really nice if there was a way to suppress low frequency noise
> (or signal, if one is so lucky) from a data vector.  This would be very
> helpful for visualizing small signals riding on large low frequency noise
> fluctuations. When viewing PSDs of real data, this option would obviate the
> frequent autoscaling problem, in which the interesting part of the spectrum
> is dwarfed by the noise at low frequencies.
>
> A command line option to implement the "Low Frequency Interference"
> subtraction would be very convenient.  The argument of the option could be
> the highpass edge in, say, units of the resolution element, or in Hz (if
> the sample rate is supplied as well).  For instance, the command line of
> this sort
>
> kst -lfi 2 -r 200
>
> would specify the sample rate (200 Hz), and the highpass edge of the filter
> required to overcome the low frequency noise in the data (2 Hz).

   Could this be done with a plugin?  Recent Kst releases support plugins 
written in C.  You can't quite reference them from the commandline, but they 
should be able to provide this functionality I think.

Comment 2 Andrew Walker 2004-08-10 01:14:06 UTC

You can do this (though not from the command line) by using one of the 
Butterworth filter plugins. They came in several variations (high, low, band, 
and notch).

Comment 3 Netterfield 2004-08-10 16:20:46 UTC

Do we need a command line interface for filters?

Comment 4 Netterfield 2004-10-19 18:15:12 UTC

The feature, as requested, will not be implemented, as it is too special case.

But, a new bug allowing command line implementation of plugins could be opened if a good UI could be come up with.