AIPS HELP file for SPECR in 31DEC20
As of Tue Jul 7 3:06:58 2020
SPECR: Spectral regridding task for uv data
INNAME Input UV data (name)
INCLASS Input UV data (class)
INSEQ Input UV data (seq. #)
INDISK Input UV data disk #
OUTNAME Output uvdata name (name)
OUTCLASS Output uv data class
OUTDISK Output uvdata disk #
OUTSEQ -1.0 32000.0 Output seq. no.
NPOINTS 2.0 8192.0 # channels in output data
INTPARM Type of smoothing + parms
0 -> FFT (recommended)
BADDISK Disk #'s to avoid
Use: Spectral regridding of UV line data. The user specifies the
number of channels required in the output database and SPECR will
regrid the data to obtain that spectral resolution. It can either
increase or decrease the spectral resolution. Some care must be
taken by the user to avoid totally over-sampling the spectra.
Output is compressed if input is compressed.
NOTE: this task does NOT apply flagging or calibration tables
to the input UV data. Run SPLIT first if that operation is
INNAME.....Input UV data file (name). Standard defaults.
INCLASS....Input UV data file (class). Standard defaults.
INSEQ......Input UV data file (seq. #). 0 => highest.
INDISK.....Input UV data file disk #. 0 => any.
OUTNAME....Output UV data name (name). Standard defaults.
OUTCLASS...Output UV data file (class).
OUTDISK....The disk # of output data. 0 => highest with space.
OUTSEQ.....Output sequence number. 0 => new file.
NPOINTS....The number of spectral channels (per IF and polarization)
required in the output data file.
INTPARM....The input visibility spectra are interpolated to the
output under control of INTPARM: With a reasonable
number of spectral channels, FFT interpolation is
probably best. If the spectra are well sampled to begin
with, then more traditional interpolation methods may be
INTPARM(1) = type of interpolation (weighted smoothing)
0 => FFT (recommended under most circumstances)
1 => Hanning
2 => Gaussian
3 => Boxcar
4 => Sinc (i.e. sin(x)/x)
5 => Exponential
6 => Median window
7 => 2 point
INTPARM(2) = the "diameter" of the function, i.e. width
between first nulls of Hanning triangle and sinc
function, FWHM of Gaussian, Exponential, width of
Boxcar and median window. Defaults (if < 0.1) are 4, 2,
2, 3, 1.99, 4 channels for INTPARM(1) = 1 - 6.
(Exponential with width 2.00 is strangely slow.)
INTPARM(3) = the diameter over which the convolving
function has value - in channels. Defaults: 1, 3, 1,
4, 3, 1 times INTPARM(2) used when input INTPARM(3) <
INTPARM(2) (after application of defaults).
BADDISK....Disk #'s to avoid for scratch files