As of Thu Jan 18 18:40:02 2018

CLCAL: Task to manage SN and CL calibration tables


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 #
SOURCES                            Source list to calibrate
SOUCODE                            Source "Cal codes"
CALSOUR                            Cal sources for calibration
QUAL            -10.0              Source qualifier -1=>all
CALCODE                            Calibrator code '    '=>all
TIMERANG                           Time range to calibrate
SUBARRAY     -32000.0     1000.0   Subarray, 0=>all,
ANTENNAS                           Antennas selected, 0=> all
SELBAND                            Bandwidth to select (kHz)
SELFREQ                            Frequency to select (MHz)
FREQID                             Freq. ID to select.
OPCODE                             Operation 'MERG','CALI',
                                   'CALP'; ' ' => 'CALP' ****
INTERPOL                           Interpolation function,
                                   choices are: '2PT','SIMP',
                                   'SELN'; see HELP for details
CUTOFF                             Interpolation limit in
                                   time (min); 0=> no limit.
SAMPTYPE                           Smoothing function
BPARM                              Smoothing parameters
ICUT              0.0              Cutoff for functional forms
DOBLANK                            Blanked value interpolation
DOBTWEEN        -1.0         1.0   > 0 -> smooth all sources
                                   together; else separate them
SMOTYPE                            Data to smooth
SNVER                              Input SN table, 0=>all.
INVERS                             Upper SN table vers in a
                                   range.  0=>SNVER
GAINVER                            Input Cal table 0=>high
GAINUSE                            Output CAL table 0=>high+1
REFANT                             Reference antenna 0=>pick.
BADDISK           0.0     9999.0   Disks to avoid for scratch


Task:  Applies solutions from a set of SN tables to selected entries
       in one CL table and writes them into another CL table. The
       input CL table should be the one applied to the data when
       determining the solutions and the output CL table is the one to
       apply when calibrating the data. Other operations on SN tables
       are also performed.
          For OPCODE='MERG', the SN tables will be merged and
       re-referenced to a common reference antenna.  The result may
       then be smoothed.  This OPCODE may be used with single-source
       as well as multi-source files.
          For OPCODE='CALI' selected SN tables are merged into a
       temporary SN table, smoothed if requested, applied to a specified
       CL table and written to the specified output CL table.  This is
       for multi-source files only.  CL entries for sources not
       included by SOURCES are dropped from the output CL table.  This
       enables multiple executions of CLCAL, writing to the same CL
       table, to build that table back up to one containing all
       sources.  However, if that table is appled to the data set
       while not yet complete, the omitted sources will be flagged on
          OPCODE='CALP' is identical to 'CALI' except that uncalibrated
       data (CL entries for sources not in SOURCES) are passed through
       instead of being dropped.  This is now (2013-Feb-18) the
       default; previously the more dangerous 'CALI' was the default.

       Considerable care should be exercised in using this task with
       OPCODE 'CALI'.  If GAINUSE is not pre-existing, then the output
       file will contain data only for the specified range of adverbs
       (e.g. time-range, source list, etc).  The data from the SN
       table(s) will be interpolated and extrapolated as needed to
       cover this range.  They are then applied to the input CL values
       to produce the output CL values.
       If GAINUSE pre-exists, then the CL values for the range of
       adverbs is replaced by the data from the input CL tables times
       the data from the SN tables and the rest of the pre-existing CL
       table is unchanged.

       Note that setting GAINUSE=0 (or OPCODE 'CALP' with GAINUSE >
       the number of input versions), creates and fills a new CL table
       that then is "pre-existing" in the above sense.

       Normally, 'CALI' is run with GAINVER and GAINUSE set to
       specific values (> 0) and kept at those values, while the other
       adverbs are used to fill in all sources and times in the
       (fixed) output CL table over multiple executions of CLCAL.
       'CALP' is usually run with GAINUSE=GAINVER=0 even when multiple
       executions of CLCAL are needed to fill in the CL table
       properly.  This leads to a number of "extra" CL tables, but
       guarantees that the initial CL information (opacity, antenna
       gains, etc) is not lost.

       See the EXPLAIN CLCAL for additional information.

  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.
  SOURCES....List of sources whose CL table entries are to be
             updated.  '*' or blank = all; a "-" before a source
             name means all except ANY source named.
  SOUCODE....Sources may be selected on the basis of the
             calibrator code given in the SU table.
                  '    ' => any calibrator code selected
                  '*   ' => any non blank code (cal. only)
                  '-CAL' => blank codes only (no calibrators)
                  anything else = calibrator code to select.
             NB: The SOUCODE test is applied in addition to the
             other tests, i.e. SOURCES and QUAL, in the
             selection of sources to process.
  CALSOUR....List of calibrators to use for updating the CL
             table.  '*' or blank = all; a "-" before a
             calibrator name means all except ANY calibrator
  QUAL.......Only sources with a source qualifier number in the
             SU table matching QUAL will be used if QUAL is not
             -1.  QUAL affects the selection of both the list of
             sources and the list of calibrators.
  CALCODE....Calibrators may be selected on the basis of the
             calibrator code given in the SU table.
                  '    ' => any calibrator code selected
                  '*   ' => any non blank code (cal. only)
                  '-CAL' => blank codes only (no calibrators)
                  anything else = calibrator code to select.
             NB: The CALCODE test is applied in addition to the
             other tests, i.e. CALSOUR and QUAL, in the
             selection of sources to process.
             CALCODE affects only the selection of calibrators.
  TIMERANG...Time range of the data to be calibrated. In order:
             Start day, hour, min. sec,
             end day, hour, min. sec. Days relative to ref.
  SUBARRAY...Subarray number to calibrate. 0=>all.
             VLBI users may have a situation in which all AIPS subarrays
             actually contain the same antennas.  CLCAL may be used to
             combines the separate SN gain tables, writing a single
             output table for "subarray 0".  Later calibration routines
             will understand that this applies to all subarrays.
             Set SUBARRAY = -32000 to request this operation; it will be
             reset to 0 if the antennas files are not identical.
  ANTENNAS...A list of the antennas to be processed.  If any number is
             negative then all antennas listed  are NOT to be included.
             All 0 => use all.  Note: when processing subsets of
             antennas separately it is very important always to use the
             same reference antenna (REFANT).
  SELBAND....Bandwidth of data to be selected. If more than one IF is
             present SELBAND is the width of the first IF required.
             Units = kHz. For data which contain multiple
             bandwidths/frequencies the task will insist that some form
             of selection be made by frequency or bandwidth.
  SELFREQ....Frequency of data to be selected. If more than one IF is
             present SELFREQ is the frequency of the first IF required.
             Units = MHz.
  FREQID.....Frequency identifier to select (you may determine which is
             applicable from the OPTYPE='SCAN' listing produced by
             LISTR). If either SELBAND or SELFREQ are set, their values
             override that of FREQID.  However, setting SELBAND and
             SELFREQ may result in an ambiguity.  In that case, the task
             will request that you use FREQID.  NOTE: CLCAL should be
             run once per FREQID.
  OPCODE.....The desired operation:     (default is now CALP)
             'MERG' requests that all selected SN tables be merged and
             the phase-like parameters (phase, delay and rate)
             re-referenced to a common reference antenna.  The merged SN
             table will be smoothed if SAMPTYPE is not blank.  The
             output will be a new SN table one higher than the
             previous maximum.  Note that this concatenates the SN
             tables, it DOES NOT multiply, divide, or replace entries.
             It is intended to be used for SN tables with solutions
             for different time ranges or sources rather than
             incremental calibration of the same source(s).  If the
             tables have the significantly different solutions for
             the same (similar) time then you probably don't want to
             MERG them.

             'CALI' requests that the merge operation be done if
             necessary and the solutions be (optionally) smoothed and
             the selected CL table entries be updated from the
             smoothed SN table.

             'CALP' is identical to 'CALI' except that uncalibrated
             data is passed through instead of being discarded.

  INTERPOL...The type of interpolation to be applied to the SN table
             when computing the CL table entries (CALI, CALP only)
             All methods will extrapolate solutions if necessary.  All
             of them limit the degree of extrapolation to no more than
             1/2 of the time difference between the two calibrations
             being extrapolated after which the nearest calibration is
             used.  WARNING: The CUBE method cannot be limited in this
             way and should not be used when extrapolation is
             '2PT ' = linear vector interpolation - the default
             'SELF' = do 2PT but only using SN entries from the same
                      source.  (New mode starting 20 April 2004.)
             'SELN' = Use only SN solution from same source which
                      is closest in time.  (This mode was called SELF
                      before 20 April.)
             'SIMP' = Simple linear phase connection between SN phase
                      entries, assumes phase difference less than 180
             'AMBG' = Linear phase connection using rates to resolve
                      phase ambiguities.
             'CUBE' = As AMBG but fit third order polynomial to phases
                      and rates.
             'POLY' = Fit a polynomial to the SN rates and delays.
                      Use the integral of the rate polynomial for the
                      phases.  (CUTOFF sets the degree.)
  CUTOFF.....Interpolation limit in time (minutes). This specifies the
             maximum time interval over which SN records will be
             interpolated to calibrate a given CL record.  0 ->
             INTERPOL='POLY' does not use this limit.  Instead CUTOFF
             sets the degree of the polynomial <= 10.
  SAMPTYPE...The type of smoothing: ' ' => none
                'BOX ' = boxcar smoothing
                'MWF ' = Median window filter
                'GAUS' = Gaussian
                'EXP ' = Exponential
                'LINE' = Linear (1 - abs(t-t0)/sigma)
                '2PT ' = Two-point
                '2PTH' = Two-point + "Hanning"
  BPARM......Parameters for smoothing function.
             Function support full width in hours.
               (1) => support time for amplitudes,
               (2) => support time for phase,
               (3) => support time for rates
               (4) => support time for singleband delay
               (5) => support time for multiband delay
             Added parameter (FWHM) for GAUS, EXP, LINE in hours
               (6) => smoothing FWHM time for amplitudes,
               (7) => smoothing FWHM time for phase,
               (8) => smoothing FWHM time for rates
               (9) => smoothing FWHM time for singleband delay
              (10) => smoothing FWHM time for multiband delay
             In all cases, the substitution for blanked and good
             solutions is governed by DOBLANK (see below)
  ICUT.......Cutoff for GAUS, EXP, LINE.  The sum of the weighting
             function in the support region must exceed ICUT for the
             smoothed value to be regarded as valid.  Be careful, a
             value of 1.5 means that the sample itself must be good
             and the sum over other good samples in the support range
             must exceed 0.5.  < 1.e-6 => 1.e-6.
  DOBLANK....Blanked value interpolation:
             > 0: replace previously blanked values with smoothed
                  values, leave previously good values unchanged.
             = 0: replace previously blanked and previously good
                  values with smoothed values.
             < 0: replace previously good values with smoothed values,
                  leave previously blanked values blanked.
             Note that DOBLANK >= 0 requires a SMOTYPE that smooths
             both phase and amplitude, namely BOTH or FULL
             NOTE: >=0 Forces SMOTYPE = 'FULL' unless BOTH is
  DOBTWEEN...> 0 => smooth all SN values regardless of source.
             <= 0 => smooth only SN values from the same source.
             Well-separated calibrators may have different phases just
             because of different atmosphere, so one would not want to
             smooth them together.  This can be achieved via doing one
             source at a time, but DOBTWEEN allows one to do all
             sources at once - at least if the choice is a simple one.
  SMOTYPE....Specified the data to be smoothed. '    '=>'FULL'
             'AMPL' = amplitude smoothing only,
             'PHAS' = phase smoothing only,
             'BOTH' = amplitude and phase
             'VLBI' = delay and rate,
             'FULL' = amplitude, phase, delay and rate.
             SMOTYPE = 'FULL' forced if DOBLANK >= 0
  SNVER......First SN table to use.  0 -> 1.
  INVERS.....Last SN table to use.  0 -> SNVER  EXCEPT if both are
             <= 0 then use all SN tables.  This will concatenate the
             SN tables and then apply them.  It DOES NOT multiply,
             divide, or replace the entries in the SN tables.  It is
             intended to be used for SN tables with solutions for
             different time ranges or sources rather than incremental
             calibration of the same source(s).  If the SN tables
             have different solutions for the same/similar source/time
             then you probably don't want to do this.
  GAINVER....Specifies the input version of the (CL) table to which the
             SN tables will be applied.     0 => highest CL table
  GAINUSE....Version number of the output CL table. Old entries in the
             CL table will be replaced.  Note: modifying version 1 is
             disallowed.  0 => highest + 1 with the full GAINVER table
             copied to GAINUSE before the process begins.  Note that
             GAINUSE may be set to highest + 1 instead and advance
             copying is done only on OPCODE 'CALP'.
  REFANT.....Reference antenna to use.  All phase-like values in the
             combined SN table will be referenced to this antenna. 0=>
             use the one used in the most solutions.
  BADDISK....A list of disks on which scratch files are not to be
             placed.  This will not affect the output file.


The process of CLCAL consists of 3 steps:

   (1) The selected SN tables are merged.  Adverbs which control this
       step are
          SNVER - first SN to use
          INVERS - last SN to use
          REFANT - re-reference phases to this reference antenna
       Beginning on 19 May 2005 this merger process became more
       complete.  Previously, "merged" tables were simply concatenated
       tables sorted into proper order.  Thus, if one of the
       contributing SN tables had solutions for a subset of the IFs
       and polarizations and another SN table had the solutions for
       the other IFs and polarizations, the two sets of records would
       both appear in the merged SN table.  Half of the records would
       have flagged solutions for some of the data and the other half
       would have flagged solutions for the rest.  This mixture of
       failed solutions could be corrected by smoothing (with DOBLANK
       >= 0) but would otherwise complicate (disrupt) step 3 below.
       Now, if two records have the same time, antenna, etc., the
       solutions are truely merged with blanked solutions replaced by
       good values.

   (2) The merged SN table is smoothed in time.  Adverbs that control
       this process are
          SAMPTYPE - type of smoothing function ' ' => none
          BPARM - parameters of smoothing function - support size
                  (time over which function has value) and function
          ICUT  - function set to 0 when value < ICUT
          DOBLANK - which SN table entries are replaced by smoothed
                  values - blanked ones, good ones, or both
          DOBTWEEN - does smoothing go over all sources or is each
                  source smoothed individually
          SMOTYPE - which of amp, phase, etc are smoothed.

   (3) The merged and smoothed SN is applied to the output CL table,
       except for OPCODE 'MERG'.  This is a confusing step:
          a) If GAINUSE=0, GAINVER is copied in its entirety to a new
             CL table.  Otherwise GAINUSE version is used as is
             (including starting with an empty file).
          b) Data selection adverbs are used to delete the SELECTED
             data from GAINUSE leaving any unselected data.  Adverbs
          C) Data from GAINVER are calibrated by interpolating
             selected (merged and smoothed) SN entries to the times in
             the CL GAINVER and then written to the GAINUSE.
             Relevant adverbs for interpolation are
                INTERPOL - function used to interpolate SN to CL
                CUTOFF - max time allowed between an SN entry and the
                         CL entry to which it might apply
             And all of the above selection adverbs plus CALSOUR
             and CALCODE are also used.  OPCODE 'CALP' allows data in
             GAINUSE which are selected but for which no SN table
             entry exists to be passed through unchanged.  Otherwise
             they are omitted.