As of Fri Jul 19 9:01:15 2024

ALVAR: Plots the Allan Variance of a UV data


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 name
QUAL            -10.0              Calibrator qualifier -1=>all
CALCODE                            Calibrator code '    '=>all
STOKES                             Stokes of output
TIMERANG                           Time range to use
SELBAND                            Bandwidth to select (kHz)
SELFREQ                            Frequency to select (MHz)
FREQID                             Freq. ID to select.
SUBARRAY          0.0     1000.0   Sub-array, 0=>all
BIF                                Low IF number to do
EIF                                Highest IF number to do
BCHAN             0.0              First channel included
ECHAN             0.0              last channel included
ANTENNAS                           Antennas to include
BASELINE                           Baselines with ANTENNAS
DOCALIB          -1.0      101.0   > 0 calibrate data & weights
                                   > 99 do NOT calibrate weights
GAINUSE                            CL (or SN) table to apply
DOPOL            -1.0       10.0   If >0.5 correct polarization.
PDVER                              PD table to apply (DOPOL>0)
BLVER                              BL table to apply.
FLAGVER                            Flag table version
DOBAND           -1.0       10.0   If >0.5 apply bandpass cal.
                                   Method used depends on value
                                   of DOBAND (see HELP file).
BPVER                              Bandpass table version
SMOOTH                             Smoothing function. See
                                   HELP SMOOTH for details.
SOLINT            0.0              Basic integration time in the
                                   UV data
DOPLOT            0.0       4.0    Selects which parameter is
                                   plotted (1-4 see help)
NPLOTS           -1.0              Number of plots per page
                                   -1 -> plot average over all
FUNCTYPE                           'LG' log in Y, linear in X
                                   'L2' log in X and in Y
DOEBAR         -1.0         1.0    > 0 => plot error bars
FACTOR                             Scale symbols by FACTOR
SYMBOL          0.0        24.0    Plot symbol number: 1 - 24
                                   0 -> 3 (circle)
LTYPE        -410.0       410.0    Type of labeling: 1 border,
                                   2 no ticks, 3 - 6 standard,
                                   7 - 10 only tick labels
                                   <0 -> no date/time
PIXRANGE                           PIXR(2)>PIXR(1) -> fixed
                                   y-axis range
DOTV           -1.0         1.0    > 0 Do plot on the TV, else
                                   make a plot file
GRCHAN          0.0         8.0    Graphics channel 0 => 1.
XYRATIO         0.0                X/Y ratio 0 -> fit TV or 1 PL
BADDISK                            Disks to avoid for scratch


Task:  This task computes the vector average of the included spectral
       channels and IFs making a grid of data at intervals of SOLINT
       in time.  It then computes the Allan Variance at each possible
       integration time "tau = i * SOLINT".  If AV(j) is the average
       at a particular tau, the Allan Variance is given by
         sigma^2(tau) = < (AV(j+2) - 2AV(j+1) + AV(j))^2 > / (2 tau)
       The task then plots sigma^2 as a function of tau for all
       possible values of tau.

       The input data must be in time order.  The task is able to
       handle gaps (in time) should they arise but the computation is
       made more complex and less reliable by such gaps.  One long
       scan would really be best.

       It prints the mean, rms, robust mean, and robust rms for
       each baseline and IF.  Spectral channels BCHAN-ECHAN are
       averaged within the SOLINT and tau == SOLINT.

       The display is in 2 groups of 4 columns, one row per baseline,
       Stokes, and IF.  The first 2 columns are the mean square Allan
       variance of vector difference (IM2- 2*IM1 + IM0)**2 +
       (RE2 - 2*RE1 + RE0)**2 where (RE2,IM2) is the amplitude
       normalized vis at point n+2, (RE1,IM1) is the normalized vis at
       n+1, etc.  plus the rms of means square variance.  The second
       pair of columns is Allan variance in phase (PH2 - 2*PH1 +
       PH0)**2 with minimization of 2 pi amibiguities.  The second
       group of four columns are the same, but with the mean square
       variance and rms computed by robust means.  Note that phases
       are in radians.
  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....Source to be copied.   '  '=> all; if any starts with a
             '-' then all except ANY source named.
  QUAL.......Qualifier of source to be copied. -1 => all.
  CALCODE....Calibrator code of sources to copy. ' '=> all.
  STOKES.....Specifies which STOKES parameters are written in the
             output data set:  ' ' => 'FULL'
               'I','Q','U','V', 'IV', 'IQU', 'IQUV'
               'RR','LL', 'RL', 'LR', 'RRLL', 'RLLR', 'RLRL'
               'VV','HH', 'VH', 'HV', 'VVHH', 'VHHV', 'VHVH'
             'HALF', 'CROS', and 'FULL' have sensible interpretations
             depending on the Stokes present in the data.  The last in
             each of the 3 rows above == 'FULL'.  Note that many
             combinations of polarizations in the input and values
             above are not supported.
  TIMERANG...Time range of the data to be copied. In order: Start day,
             hour, min. sec, end day, hour, min. sec. Days relative to
             ref. date.
  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.
  SUBARRAY...Sub-array number to copy. 0=>all.
  BIF........First IF to include.  0 -> 1.
  EIF........Last IF to include.   0 -> max.
  BCHAN......First channel in spectral average. 0=>all.
  ECHAN......Highest channel in average. 0=>all higher than BCHAN
  DOCALIB....If true (>0), calibrate the data using information in the
             specified Cal (CL) table for multi-source or SN table for
             single-source data.  Also calibrate the weights unless
             DOCALIB > 99 (use this for old non-physical weights).
  GAINUSE....version number of the CL table to apply to multi-source
             files or the SN table for single source files.
             0 => highest.
  DOPOL......If > 0 then correct data for instrumental polarization as
             represented in the AN or PD table.  This correction is
             only useful if PCAL has been run or feed polarization
             parameters have been otherwise obtained.  See HELP DOPOL
             for available correction modes: 1 is normal, 2 and 3 are
             for VLBI.  1-3 use a PD table if available; 6, 7, 8 are
             the same but use the AN (continuum solution) even if a PD
             table is present.
  PDVER......PD table to apply if PCAL was run with SPECTRAL true and
             0 < DOPOL < 6.  <= 0 => highest.
  BLVER......Version number of the baseline based calibration (BL) table
             to apply. <0 => apply no BL table, 0 => highest.
  FLAGVER....specifies the version of the flagging table to be applied.
              0 => highest numbered table.
             <0 => no flagging to be applied.
  DOBAND.....If true (>0) then correct the data for the shape of the
             antenna bandpasses using the BP table specified by BPVER.
             The correction has five modes:
             (a) if DOBAND=1 all entries for an antenna in the table
             are averaged together before correcting the data.
             (b) if DOBAND=2 the entry nearest in time (including
             solution weights) is used to correct the data.
             (c) if DOBAND=3 the table entries are interpolated in
             time (using solution weights) and the data are then
             (d) if DOBAND=4 the entry nearest in time (ignoring
             solution weights) is used to correct the data.
             (e) if DOBAND=5 the table entries are interpolated in
             time (ignoring solution weights) and the data are then
             IMAGR uses DOBAND as the nearest integer; 0.1 is therefore
  BPVER......Specifies the version of the BP table to be applied
                0 => highest numbered table.
               <0 => no bandpass correction to be applied.
  SMOOTH.....Specifies the type of spectral smoothing to be applied to
             a uv database . The default is not to apply any smoothing.
             The elements of SMOOTH are as follows:
             SMOOTH(1) = type of smoothing to apply: 0 => no smoothing
               To smooth before applying bandpass calibration
                 1 => Hanning, 2 => Gaussian, 3 => Boxcar, 4 => Sinc
               To smooth after applying bandpass calibration
                 5 => Hanning, 6 => Gaussian, 7 => Boxcar, 8 => Sinc
             SMOOTH(2) = the "diameter" of the function, i.e. width
               between first nulls of Hanning triangle and sinc
               function, FWHM of Gaussian, width of Boxcar. Defaults
               (if < 0.1) are 4, 2, 2 and 3 channels for SMOOTH(1) =
               1 - 4 and 5 - 8, resp.
             SMOOTH(3) = the diameter over which the convolving
               function has value - in channels.  Defaults: 1,3,1,4
               times SMOOTH(2) used when input SMOOTH(3) < net
  SOLINT.....Pre-averaging time in seconds.  0 -> 10.
  DOPLOT.....The task computes 4 different Allan variances
             (1) Mean of vector amplitude of normalized visibilities.
             (2) Mean of phase adjusted to minimize 2*pi ambiguities
             (3) Median of vector amplitude of normalized visibilities.
             (4) Median of phase adjusted to minimize 2*pi ambiguities
             DOPLOT selects which one is plotted with 0 => 3.
  NPLOTS.....Number of panels per plotted page.  0 -> 2
             -1 => plot the average over all included baselines
  FUNCTYPE...'L2' log in both X axis (tau) and Y axis (Allan variance)
             'LG' log in Y axis, linear in X axis
             else linear in both
  DOEBAR.....> 0 => Plot error bars (+- 1 rms)
  FACTOR.....Scale plot symbols by FACTOR     0 -> 1.
             If FACTOR < 0, draw lines between the points and use
             abs(FACTOR) to scale the points plotted.
  SYMBOL.....Choices are:
              1: Plus sign           13: Star of David
              2: Cross (X)           14: Seven-pointed star
              3: Circle              15: Eight-pointed star
              4: Box                 16: Nine-pointed star
              5: Triangle            17: Ten-pointed star
              6: Diamond             18: 11-pointed star
              7: Pentagon            19: 12-pointed star
              8: Hexagon             20: 13-pointed star
              9: Septagon            21: 14-pointed star
              10: Octagon            22: Plus (+) with gap
              11: Nine-gon           23: Cross (X) with gap
              12: Five pointed star  24: Vertical line
             0 -> 3
  LTYPE......Labelling type, see HELP LTYPE for details:
             1 = border, 2 = no ticks, 3 or 7 = standard, 4 or 8 =
             relative to ref. pixel, 5 or 9 = relative to subimage
             (BLC, TRC) center, 6 or 10 = pixels.  7-10 all labels
             other than tick numbers and axis type are omitted.
             Less than 0 is the same except that the plot file
             version number and create time are omitted.
             Add n * 100 to alter the metric scaling.
  PIXRANGE...Plot Y axis with this range.  Note that on L2 and LG this
             adverb is in logarithm base 10.
  DOTV.......> 0 -> use the TV; else make plot file(s)
  GRCHAN.....Limit plot to one graphics channel; 0 -> use channels 1
             (labels), 2 connecting line, and 4 (symbols and error
  XYRATIO....X/Y plot ratio, 0 -> 1 for plot files, TV dimensions for
             DOTV true.
  BADDISK....The disk numbers to avoid for scratch files (sorting
             tables mostly).