Logged on 07/20/2009 10:09:40 PM
The runtime options should pop up but before you click 'simulate MS' we'll open a viewer to examine the bandpass.
Cancel the runtime options window and expand the tree from the root nodes. Referring to the screen grab below will help.
Find the sink corresponding to baseline 0:1 and keep expanding it. You should be able to see the visibility generated by this baseline for source SSSC25 furthest down (or up) this branch of the tree, and see the hierarchy of operations, in this case the simulated B- and G-Jones antenna-based corruptions.
A nice feature of MeqTrees is that you can visualise any node in the tree. You might have read how to do this elsewhere but here it is again:
We want to examine the bandpass so right click the B:0 node and select publish. You should see a little newspaper-type icon appear next to it. Right click again and select 'new display with' and then 'results plotter' from the sub menu.
A blank viewer should spring up, ready to be filled with the values as they come in when the tree is executed. The Meqbrowser is intelligent here in that it examines the structure of the node and generates a suitable plot without you having to think about it.
Press the 'TDL Exec' switch again, make sure the 'output column' is set to 'DATA' and click 'simulate MS'.
You should then see a plot resembling the one in the screen grab below. A couple of things to note:
1) What we've done is put a simple gain slope across the bandpass. If you're short of something to do then you could try calibrating this using the B-Jones option in the WSRT Calico scripts. Remember we're omnipotent for the open challenges and we know for certain that we have a spectrally flat 10 Jy point source at the phase centre.
2) You can see from the tree that the B- and G-Jones are antenna based. Note how the conjugate point has B and G operations corresponding to the second antenna index in the baseline pair. You could re-write the bandpass TDL code if you wanted to simulate a different bandpass for each receiver.
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