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Frames

At NPOI, a fringe frame is a two-dimensional array of count rates, whereby one dimension corresponds to the 8 or 64 phase bins across the fringe, and the other dimension corresponds to the channel axis. A frame is recorded every 2 ms. The frames are stored in bincounts, which can have dimensions, in this order, of the number of spectrometers, number of bins, number of channels, and the number of frames. This structure is the same whether or not one is using the 3 or 6 way beam combiners. All COBRA functions are guaranteed to work if a single spectrometer is selected; only a few accept frame or visibility variables with a spectrometer index, as noted specifically below. Therefore, the default is that the bincounts array does not have a spectrometer index.

displayframe, c

Display frames on the TV. Any index selections in the different dimensions can be displayed, provided all phase bins are always selected. Examples: displayframe,bincounts(0,*,*,0), displayframe,bincounts(0,*,0,0:99).
rotateframe(c, l, a, g)
Function. Apply rotation by group delay $d$ and airpath $a$ to fringe frame $c$ and return rotated frame.
fringeframe(a, g, l, v, n[, /poisson])
Function. Return a simulated fringe frame for a given path in air, $a$, delay tracking offset (group delay), $g$, wavelength grid, $l$, visibility amplitude, $v$, and photonrate, $n$. Optionally include Poisson noise. $a$ and $g$ can be arrays, as well as $v$ and $n$. The number of bins is inferred from the genconfig.numbin variable. The default number of bins is 8.


next up previous contents
Next: Visibilities Up: Introduction Previous: Reading raw HDS scan   Contents
Christian Hummel 2009-10-20