shape truncation

Stefan Berger (BERGER@ps1515.chemie.uni-marburg.de)
Tue, 16 Aug 1994 08:41:26 MDT

working with gradient enhanced spectroscopy one likes to calibrate
the field strength of the the gradient pulses.

For normal work, usually sine shaped field gradients are used, which
are defined with the gradshapes program (UXNMR). By doing this, one
is asked for a truncation level which cuts e.g. at the BOTTOM of the
sine function the first 1%.

Calibration is usually performed with the block function. If, for
analogy reasons, one inserts a 1% truncation level, this leads to a
cut off at the TOP of the block function, which means that 99% of
the block ar cut off. Of course, this is by no means more comparable
to a sine function with 1% cutoff at the BOTTOM.

We have not found any hint in the manuals about this. Although in
pure mathematical terms perhaps logically, the average user might not
be aware of it. Thus, if you want a full block function, use a
truncation of 100%; this is indeed gradient enhanced....

stb