There are some cases where one may have to change them afterwards. This makes only sense if those parameters have been set by apk or manual phase correction. Phase correction and window functions have to be defined before processing in edp . Important for T 1 or kinetic measurements. The larger lb , the broader the line.
Optimal value is lb natural line width in Hz.
Use commands em or ef gaussian apply gaussian multiplication, enhances resolution at cost of signal to noise. Use commands gm or gf . Important for truncated data like 2D files. This is the default for most 2D experiments. It is also controlled by the parameter ssb as described above.