Content-type: text/html Manpage of uvdecor

uvdecor

Section: User Commands (1)
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NAME

uvdecor - Apply decorrelation correction to visibility file  

PERSON RESPONSIBLE

pjt  

CATEGORIES

uv analysis  

DESCRIPTION

UVDECOR acts similarly to UVCAT but applies a correction factor (>1) to the visibility amplitudes to account for the amplitude loss due to decorrelation. The integration time is divided by the square of the correction factor to reflect the increased noise. The correction factor is normally derived from the CARMAphase monitor data, which is scaled to the appropriate frequency, baseline, and elevation using a simple prescription for 3D Kolmogorov turbulence. This task should be used with caution, as the correction is only valid over long (>10 min) averaging intervals, and the assumption of 3D turbulence is unlikely to apply on long (>100m) baselines.

Another optional correction factor should be derived, again with caution, for CARMA data preceding 26-aug-2007 where decorrelation was present down to about 8000 ns in the delaylength difference between two antennas.  

PARAMETERS

vis
The names of the input uv data sets. Multiple names can be given, separated by commas. At least one name must be given.
select
The normal uv selection commands. One unusual aspect of this is that the "window" subcommand can be used to select which windows are copied to the output file (normally the "window" only has an effect for velocity line type). The default is to copy everything.
rmpmax
1 or 2 parameters. First, maximum acceptable value for rmspath in microns. Default=2000. Second, type of replacement for bad values: "zero" to set rmspath=0 (no correction), "extrap" to use previous value. Default="zero".
cormax
Maximum allowed correction factor for the visibility amplitude. If correction is not prevented by rmpmax, it can still be prevented at this stage. Default=100.
stokes
If a value is given, uvdecor converts the input into the required polarizations before writing to the output. Default is to copy across the polarizations present in the input files.
delaymax
If used, this will be the delay difference length (in nanosecs) at which the decorrellation would have been 0. If 0 is set, this option is not used. A good value for CARMA data prior to 26-nov-2007 is about 8500 (TBA).
options
This gives extra processing options. Several options can be given, each separated by commas. They may be abbreivated to the minimum needed to avoid ambiguity. Possible options are:
   'nocal'       Do not apply the gains file. By default, UVDECOR
                 applies the gains file in copying the data.
   'nopass'      Do not apply bandpass corrections. By default, UVDECOR
                 applies bandpass corrections if possible.
   'nopol'       Do not apply polarization correction. By
                 default UVDECOR corrects polarizations, if possible.
   'nowide'      Do not copy across wide-band channels.
   'nochannel'   Do not copy across spectral channels.
   'unflagged'   Copy only those records where there are some
                 unflagged visibilites.
out
The name of the output uv data set. No default.


 

Index

NAME
PERSON RESPONSIBLE
CATEGORIES
DESCRIPTION
PARAMETERS

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Time: 18:35:38 GMT, July 05, 2011