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CLIC\TABLE Name [OLD|NEW] [/COMPRESS tmax uvmax]
[/RESAMPLE nc ref val inc code shape width] [/FFT]
[/FREQUENCY name rest-freq] [/DROP n1 n2]
This command will create an UV data Table from the current index. is
not given, the most recently created table will be extended. Next argu-
ment may be OLD (default value if not specified) to extend and existing
table, or NEW to create a new table.
The bands and subbands used must have been given by the command SET SE-
LECTION. The weighting mode can be modified by the command SET WEIGHTS.
TABLE /RESAMPLE nc ref val inc code [shape width /FFT]
Option /RESAMPLE enables to resample data on a new spectral grid
(for line data). 'nc' is the output number of channels, 'ref' the
reference channel, 'val' the value of velocity or frequency offset
(with respect to the rest frequency) at the reference channel, 'inc'
the resolution, 'code' is "V" if the value 'val' and the resolution
'inc' are in velocity units, "F" for frequency units.
The reference channel thus corresponds to the given 'val' velocity,
or to the offset 'val' in MHz from the rest frequency present in the
header or modified by option /FREQUENCY.
Resampling is done by default through linear interpolation of input
channel data. Resampling may also be done (using option /FFT) in
Fourier space by cut-off or extrapolation (by zeroes) of the Fourier
components, after deconvolution by the channel response of the cor-
relator (due to on-line apodization), and followed by reconvolution
to produce frequency channels of the given 'shape' and 'width'. Al-
lowed shapes are:
TBox = a box in delay space (unapodized correlator)
Ppar = a parabola in delay space (apodized correlator) (the de-
FBox = a box in frequency space (square filter)
FTri = a triangle in frequency space (Hanning smoothed square fil-
The width is the channel width in units of channel separation (de-
Option /FFT is not recommended when joining together several sub-
bands to produce a single spectrum, with a limited number of broad
channels. In those cases using the FFT could produce a spectrum
with "holes" at the points between subbands with limited overlap.
TABLE /FREQUENCY name rest-freq
Option /FREQUENCY is used to redefine the rest frequency (in MHz)
and line name for the output table. The velocity scale is computed
accordingly. This rest frequency will correspond to the reference
channel in option RESAMPLE.
TABLE /NOCHECK [SOURCE|POINTING|PHASE|EPOCH]
When processing each scan, CLIC checks whether a number of position
parameters are consistent with those defined in the table header.
Option /NOCHECK allows to switch off this checking. Arguments can
be given to switch off only part of the parameters (SOURCE name,
POINTING direction, PHASE center, EPOCH of coordinates). This option
is intended for building tables with inconsistent parameters (typi-
cal exemple is a different source name...). It is potentially dan-
gerous and is to be used with caution.
TABLE /DROP n1 n2 --- THIS OPTION IS OBSOLETE
Option /DROP enables to drop the first 'n1' and last 'n2' channels
in each subband of the OLD spectral correlator. For the NEW spectral
correlator (data taken since summer 1992), it is replaced by the
commands SET GIBBS and SET DROP.
TABLE /COMPRESS tmax uvmax
Option /COMPRESS is used to compress the data before writing the
table. This works like the COMPRESS command, but no intermediate
file is written. Very seldom used.