>> We are looking to apply a digital filtering approach to a stage of our smurf based ORAC-DR pipeline, as this has proven advantageous in related experiments with IDL. We're wondering if there are one dimensional convolution routines available in Starlink that do not use FFT. If so, any documentation and examples would be most helpful.
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> Are you looking for a library or an actual application? And what kind of filter do you have in mind?
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> There are boxcar and tophat filters in smurf/libsmf. In terms of applications there are BLOCK and GAUSMOOTH in KAPPA for example.
Our main goals are baseline removal, and background atmospheric noise reduction in FTS based interferograms.
The IDL CONVOLV function has proven to be very effective in removing the baseline of the interferograms in the FTS pipeline, by flattening their low frequency curvatures. It also effectively reduces background noise.
Other methods were also tried, including curve fitting, average value subtraction, but none worked nearly as well as convolving, so we are looking for a Starlink equivalent that can be used as a new step in our data reduction pipeline between initialization and phase correction.
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