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SPECTRAL PARAMETERS


SPECW, OFFSET, UNIT, FREQ

These contexts describe the spectral widths (SPECW) of the spectrum and offset (OFFSET) of the right-most point of the current data-set, thus creating a frequency reference for the data-set. Values are in Hz. Frequencies are used by EM, GM, and changed by EXTRACT (but not CHSIZE, be careful.). The calib macro permits to set the offset in an interactive manner. When no information is available on the current data-set the OFFSET is set to 0 and the spectral widths to 2000*Pi.

The context FREQ holds the basic frequency of the spectrometer (in MHz). It is used to compute ppm from Hz. The context UNIT will tell other commands (POINT, PKLIST, etc...) to choose the unit used. UNIT can take the values INDEX (number of channel) HERTZ (based on SPECW and OFFSET), PPM (HERTZ divided by FREQ), and SECOND(based on SPECW). All other values are invalid.

size, list

These two macros permits examination of the current state of the data-set. size is a simple one-line text. list is a comprehensive output. (used to be commands).

EXTRACT

permits to extract a given part of a spectrum and thus becoming the new data-set. EXTRACT is used as ZOOM but is obviously not reversible.


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