Reducing data

The program has a few different options for discarding unwanted parts of the spectrum, such as excess baseline at the edges.

SH - Shrink

This can be thought of as the inverse of zero-filling.  By default, the right-hand half of the data is discarded.  

It is possible to specify the number of points to be discarded, by either specifying number of points or a percentage of the data.

sh n - discards n points from the right end of the data.  

sh % n - the number of points discarded is n percent of the data points.  

XT or Extract 

This command discards an equal number of points from each end of the spectrum, rather than just from the right end.  The amount can be specified as a percentage; as number of data points, Hz or ppm; or using the current zoom limits.

xt (or xt 1D) - Discards all data points outside the current zoom limits.

xt n m (or xt 1D n m) - Extract the first dimension data between data points n and m

xt ppm n m - Extract the spectrum between chemical shifts n and m, specified in ppm

xt hz n m - Extract the spectrum between frequency limits n and m, specified in Hz

xt % n - Discards n percent of the data points from each end

xt 2D - Discards all slices outside the current zoom limits.

xt 2D n m - Extract the second dimension data between slices n and m

This command is particularly handy for use with digitally filtered data, in which the data points at each end are distorted.  To make application of this command a bit simpler, the following options have been added:

xt JEOL - discards 5% of the data points from each end

xt Bruker - discards 2% of the data points from each end

Last updated: 2/16/08