Using a model SRF and fringes, we have investingated the effects of fringe position on SRF channel center position and width. The effects depend upon the channel frequency, so we have modelled two representative channels in the 1300 and 2300 cm-1 regions.
2300 cm-1
The 9 colored curves on the plots are for various depths of the fringes; from 2 to 18 percent deep peak-to-peak deep in transmittance. The x-axis is the distance (in percent) the fringe center is from the channel center. 0 and 100 precent are identical; the original fringe location has been exactly replaced by an adjacent fringe.
The top two plots show the effects of shifting fringe location on the apparent position of the channel center (top) and SRF peak (middle) frequency. The y-axis is in units of fraction of a FWHM.
The bottom plots shows the effect of shifting fringes on the channel width. Note that depending upon where the fringes fall, the apparent width can be narrower or wider than the true (fringeless) width.
1300 cm-1
Except for the channel frequency, this plot is identical to the plot above.