Interactive Channel/Baseline Flagging - TVFLAG

The task tvflag is akin to the AIPS SPFLG: it displays, on a TV device, one baseline at a time, the amplitude or phase (or amplitude or phase difference from a running average computed over some time). Task tvflag will cycle over the set of baselines present, displaying each one, and giving you the opportunity to flag each baseline.

Task tvflag is the last useful remnant of the ``TV'' suite of software (an old package of display software within Miriad), which uses two X-windows based tools, xmtv and xpanel, for displaying. You will need to start up these tools before using tvflag. To start these, use commands

     % xmtv &
     % xpanel &
in a terminal window of your local workstation (which need not be the machine that you are running tvflag on). To use these, you first have to ensure that you are correctly setup to use X-windows programs - see Chapter 3 for more information on using X-windows. Using xmtv and xpanel is simple enough when you can run them on your local workstation. If you have to run xmtv and xpanel from a compute server (e.g. the situation in Narrabri, when using kaputar via an NT workstation), then there can be problems arising from multiple users attempting to allocate a given TCP/IP port. See Appendix E for more information.

The input parameters to tvflag are pretty straightforward. We mention only the more useful ones:

Typical inputs are:

vis=vela.line Specify visibility dataset
server=xmtv@lupus Specify TV server
mode=amp Display amplitude
tvchan Unset is channel 1 else specify
range Unset for intensity auto-scale
tvcorn Unset to centre the image
line Unset for all channels
taver Controls the computation of the
  running mean for the DIFF command.

After invoking tvflag, a control panel will pop up and a baseline of data will be displayed on the TV. The display shows channels along the x-direction and time along the y-direction. A gap in time in the data is shown by a dark gap. A wedge is displayed both above and to the right of the data. The top wedge is the data averaged over time, whereas the wedge to the right is the data averaged over the channels.

You now perform flagging operations by pressing ``buttons'' on the control panel. We review the meaning of some of the buttons:

There are other buttons on the control panel - but we do not suggest that you use these. They reproduce (rather crudely) buttons on the TV display window. The useful buttons on the TV display are:

One shortcoming of tvflag is that it averages the data in time so that it will fit on the display. Unfortunately full time resolution display cannot be recovered. To display the data at full time resolution, you may need to select the data in chunks (with select=time()).

Miriad manager