AIPS HELP file for REIFS in 31DEC22
As of Tue May 30 11:11:43 2023
REIFS: Makes more IFs with fewer channels across IF boundaries
INNAME Input UV file name (name)
INCLASS Input UV file name (class)
INSEQ 0.0 9999.0 Input UV file name (seq. #)
INDISK 0.0 9.0 Input UV file disk unit #
BCHAN 0.0 First channel included
SPECIAL COUNTING RULES APPLY
ECHAN 0.0 Last channel included
SPECIAL COUNTING RULES APPLY
NIF 1.0 90.0 Break into NIF IFs
OUTNAME Output UV file name (name)
OUTCLASS Output UV file name (class)
OUTSEQ -1.0 9999.0 Output UV file name (seq. #)
OUTDISK 0.0 9.0 Output UV file disk unit #.
FQCENTER >= 0 -> center frequency axis
Task: This task is designed to change a data set with multiple
spectral windows each having multiple spectral channels into a
data set with NIF spectral windows ("IFs") each with
appropriately fewer spectral channels. Some calibrations and
normalizations are done on an IF basis (e.g., CALIB solutions,
BPASS normalizations) and this task allows those to be done
over a smaller range of frequency or spectral channel number.
** NOTE however that REIFS allows you to combine more than one
input IF into one output IF. The averaging of IF-dependent
calibration numbers in such cases is at best problematical. **
Task NOIFS may be used to reduce all IFs to a single one. This
causes a loss of information for on-line tables with
IF-dependent columns such as the SysPower and CalDevice
tables. This was then followed by MORIF to break into small
IFs in order to handle spectral index variations better. This
task combines the two, taking an appropriate average of the
table data should a new spectral window contain portions of
more than one old spectral window.
REIFS requires the input IFs to cover the frequency range
fully, without overlap and with the channel separations in each
IF being the same. MORIF does not have these restrictions.
If you want NIF out = 1, NOIFS can handle cases involving gaps
and overlaps in the spectral windows although all inncrements
must be the same.
INNAME.....Input UV file name (name). Standard defaults.
INCLASS....Input UV file name (class). Standard defaults.
INSEQ......Input UV file name (seq. #). 0 => highest.
INDISK.....Disk drive # of input UV file. 0 => any.
BCHAN......Lowest channel included where channels are counted from 1
in the lowest IF to Nchan * Nif in the highest IF.
ECHAN......Highest channel included in this same special counting
NIF........Number of output spectral windows (IFs). The total
number of included channels (ECHAN - BCHAN + 1) must be
an integer multiple of NIF. If ECHAN is too high to meet
this requirement, the highest numbered channels will be
omitted (with a suitable warning message).
OUTNAME....Output UV file name (name). Standard defaults.
OUTCLASS...Output UV file name (class). Standard defaults.
OUTSEQ.....Output UV file name (seq. #). 0 => highest unique
OUTDISK....Disk drive # of output UV file. 0 => highest with
space for the file.
FQCENTER,..> 0 => Change frequency axis reference pixel to
Nchan / 2 + 1 (where Ncahn is the new number
of channels in an IF)
else => do not change reference pixel