[Kst] [Bug 158887] New: LFI differencing plugin for sky and reference data
Andrew Walker
arwalker at sumusltd.com
Fri Mar 7 00:33:25 CET 2008
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http://bugs.kde.org/show_bug.cgi?id=158887
Summary: LFI differencing plugin for sky and reference data
Product: kst
Version: unspecified
Platform: Compiled Sources
OS/Version: Linux
Status: NEW
Severity: wishlist
Priority: NOR
Component: general
AssignedTo: kst kde org
ReportedBy: arwalker sumusltd com
Version: 1.6.0 (using KDE 3.5.9)
Installed from: Compiled From Sources
OS: Linux
The following was requested by the LFI team:
LFI reference loads are at a different temperature then the sky signal, therefore in order to reduce the 1/f noise it is necessary to include in the difference a scale factor r (sky - r * ref).
The default LFI differencing procedure is to take the mean of 1 hour of sky and ref, compute the r factor as mean_sky/mean_ref, and then produce the differenced timestream by computing sky - r * ref.
differencing plugin implementation
Inputs:
sampling_freq (the same for sky and ref)
sky datavector
ref datavector (of the same lenght and sampling rate)
timespan (hours) where to compute the r factor, default is 1, if empty the complete vectors are taken into account
Pseudocode:
totaltime = (number of samples) / sampling_freq
for i from 0 to totaltime/timespan:
data_range = [ i * timespan * sampling_freq : (i+1) * timespan * sampling_freq ]
mean_sky = mean(sky [data_range])
mean_ref = mean(ref [data_range])
r[i] = mean_sky/mean_ref
diff[data_range] = sky[data_range] - r[i] * ref[data_range]
output:
r (vector containing computed r for each timespan, dimension is the number of timespans in the sky and ref datavectors)
diff (datavector of the same dimensions of sky and ref)
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