The Suggested Number of Samples

If the Nyquist rate were desired (assuming the structure in the line spectrum were commensurate with the width of a resolution element), then the Sampling Interval would naturally be set to 2 to recover all information. Yet, in practice for LWS01 and LWS02, there is almost certainly structure in the line profiles that will never be resolved by the LWS. The suggestion is made to record four samples per resolution element because then there will be four (non-independent) samples of the line intensity from which to form a measuremet of the strength and perhaps the width. Were there only two samples per resolution element, and they differed, it would then be difficult to reach a consensus from the data.

Two samples per resolution element are suggested if and only if time savings are critical or if the line or continuum is not expected to vary appreciably across a resolution element.

This example will let you figure out how your samples will be arranged vs. wavelength and how many will be done for LWS02 and LWS04. Suppose the scan width is 3. There will be 3 resolution elements on either side of the central one:

        X   X   X   X   X   X   X   X

wavelength -->

If there are 4 samples per resolution element, 
these are filled in like this:


wavelength -->

Finally, the LWS02 and LWS04 algorithm leaves
the endpoints off:


wavelength -->