[ Basic Info | User Guide ]

Basic Information on tvclip

Task: tvclip
Purpose: Interactive editing of a UV data set on a TV device.
Categories: calibration, uv-data, tv, plotting, display

      program tvclip
      TVCLIP is a MIRIAD task which allows interactive baseline
      editing of a UV data set.  The user should make sure,
      if the display device is capable of creating menus that
      the menu program has been loaded ``before'' running this
      routine (eg. xpanel for the XMTV) - see the User's Guide
      or Cookbook under TV Devices for details.
      When this program is run, each baseline is displayed,
      one at a time, with the x-axis representing channel
      number (increasing to the right), the y-axis representing
      the change in time (increasing upward), and the color
      intensity representing the amplitude or phase (depending
      on the value of the keyword ``mode'') of the visibility.
      The current antenna that constitute the baseline are
      labeled at the bottom of the plot (if room permits).
      In addition, if room permits, a color wedge is displayed
      to the right side of the visibility data and is the sum
      of the data over all displayed channels.  Also, a wedge
      of the sum of the data over all displayed times will
      appear above (or below) the data as room permits.
      The user may edit the data in one of two ways: 1) By
      entering commands at the keyboard; or 2) by selecting
      commands from the listed menu items.  Which method is
      determined by the presence of a menu program (such as
      ``XPANEL'' for the Sun systems).
      If no menu program is currently active, then a message
      is issued to the user and all commands are prompted from
      the keyboard.  Commands are entered followed by a carriage
      return (<CR>).  Single letter abbreviations are used for
      all commands.  The current command list, each corresponding
      abbreviation, and a brief description of each command is
      available by entering a question mark (``?'') as a command.
      Commands requiring further interaction (eg. ``select'' and
      ``value'') will prompt the user when they are invoked.
      If a menu program is active, then TVCLIP will attempt
      to construct an assortment of menu buttons and other
      items that will perform the equivalent of entering commands
      at the keyboard.  Certain commands (eg. ``select'' and
      ``value'') require further cursor input and will prompt
      the user for a particular action (for example: ``select''
      will request the user to select the region to box for
      further flagging commands).
      The current technique of editing is to load the baseline
      to be edited, zoom and pan to the desired location, and
      then, select the region to be edited followed by an
      editing command.  To identify a region to edit, chose
      the ``select'' command (or ``channel'' or ``time'' select
      options) and then use the cursor to box the desired points.
      To select a desired region, move the cursor (mouse) to a
      corner of the region to select; identify, to the program,
      the corner (usually by pushing and holding the left mouse
      button); move the pointer to the other corner (by dragging
      the mouse), and then identify, again to the program, the
      other corner (usually by releasing the left mouse button).
      After the region to edit has been identified, the selected
      region may be flagged as good or bad using the appropriate
      editting command (or button).  If data is flagged improperly,
      the ``undo'' command will reverse the last editing operation.
      NOTE:  If the device does not support this type of ``rubber-
      band'' selection (Eg. XMTV does; MXAS does not), then the
      user will be asked to use the cursor to identify two opposite
      corners to delimit the selected region.
      To save the editing done to a particular baseline, use
      the ``exit'' command (or select the ``exit'' button).
      The flagging changes will be immediately applied to the
      data.  To NOT save the changes made to a particular
      baseline, use the ``quit'' command (or button).  After
      a ``quit'' or ``exit'' operation, the data for the next
      baseline is loaded onto the display and the user may continue
      editing.  Selecting the ``abort'' command (button) at any
      time will perform the same operation as ``quit'', but
      will also terminate the program.
      You can use the 'batch-mode' of tvclip if you have a lot of
      similar flagging to do. Use tvclip in interactive mode to
      determine a good clip level and a sequence of DIFF and CLIP
      commands that is appropriate for your data. Then set the
      clip level and enter the commands in the 'commands' keyword.
      You can then either watch the automatic flagging on the tv,
      or switch off the display (options=notv) to speed things up.

Key: vis
      The name of the input UV data set.  A visibility file name
      must be supplied.  Only one file may be edited at a time.

Key: server
      Standard keyword server. See the help on server for more information.

Key: tvchan
      An integer specifying which TV channel the data is
      displayed.  The default is channel 1.

Key: range
      The minimum and maximum range used in scaling the data
      on the TV.  Default is to autoscale to the first image.
      If this keyword is used, TWO parameters must be input.

Key: tvcorn
      The integer device coordinate of the lower left corner
      of the image.  The default is to center the image on the
      display.  If this keyword is used and only the x coordinate
      value is input, the y coordinate value is set to the x value.

Key: line
      Standard keyword line. See the help on line for more information.
      NOTE: Here ``type'' must be `channel' or ``wide'' and the maximum
      of  both ``width'' and ``step'' must be 1.  The default is
      to display all channels.

Key: mode
      Display ``amplitude'', ``phase'', ``real'', ``imaginary''.
      By default, ``amplitude'' is selected. For mode=phase, the
      phase is in degrees.

Key: taver
      The length of time (in minutes) used to average the data when
      determining the running mean. This is used with the "DIFF"
      command, where the running mean of the data are subtraced off.
      Two values can be given for taver, being TTOT and TGAP
      respectively. If the time interval between any
      two successive data points is greater than TGAP, or if the
      total time between the first data point in an average
      and any succeeding data point exceeds TTOT, then a new
      average is started.  The default for TTOT is 5 minutes, whereas
      the default TGAP is the value of TTOT.

Key: clip
      The clip level (in average absolute deviations, a parameter
      similar to rms, but less sensitive to outliers)
      This is used with the "CLIP" command. All data more than clip
      times the av. abs. dev. from the median will be clipped.
      This clip operation is repeated until no more points are clipped.
      Common values are 4,5,6. Flagging on stokes V data with clip=4
      usually gets rid of most interference. The default is 5.

Key: options
      Extra processing options. Several are possible:
        'nochannel', 'notime' and 'nopixel' are clip options.
                By default the "CLIP" command will flag channels, times
                and individual pixels with an rms that is too far from
                the median.  These options allow you to exclude some
                forms of clipping.
        'notv'  display option, do not show anything on the tv.
                Speeds up non-interactive clipping.  This can only be
                used if you also fill in the commands keyword.  Because
                with 'notv' the data does not have to fit on the screen,
                less time averaging is needed.  Usually the data will be
                flagged at full time resolution.
        'nosrc' Do not cause a break in the display when the source
                changes. Normally TVFLAG puts a gap in the display
                whenever the source changes.

Key: commands
      This allows non-interactive flagging using the "CLIP" command.
      Use this to specify a sequence of flagging commands to be applied
      for each baseline, e.g., commands=diff,clip.
      The "EXIT" command is implicitly added at the end of the list.
      You will not be able to interact with tvclip using mouse or
      keyboard if "commands" is set.

Key: select
      Standard keyword select. See the help on select for more information.
      NOTE: The default is to use all visibilities.
Revision: 1.13, 2021/06/02 04:45:09 UTC

Generated by miriad@atnf.csiro.au on 02 Jun 2021