FREQ limits breaking in AIPS
When creating nominal ANTAB files within
antab_editor.py I noticed that (at least) for some cases the frequency range written in FREQ doesn't fully cover the observed frequency range that AIPS expects.
For example, in RG012E (see generated ANTAB in jop83:/jop83_0/pipe/in/marcote/rg012e/rg012e.antab), for CM it wrote:
FREQ = 4958.49, 5022.49
which are the reference frequencies for the edge channels in the vix file:
def 4958.49MHz2x64MHz; * mode = 1 stations =Cm:Da:De:Kn:Pi sample_rate = 128.000 Ms/sec; * (2bits/sample) chan_def = : 4958.49 MHz : U : 64.00 MHz : &CH01 : &BBC01 : &NoCal; *Rcp chan_def = : 4958.49 MHz : U : 64.00 MHz : &CH02 : &BBC09 : &NoCal; *Lcp enddef;
In principle this should be OK. But AIPS breaks saying that the last IF is not covered. The actual freq. limit for it is the same but I wonder if AIPS still considers an overhead related to the spectral channel width (0.5 MHz). Adding this quantity fixes the issue.
Could you thus add an extra 1 MHz (for example) on the frequency limits there? This should make these cases to work properly. In any case this would not create any extra issue.
Looking at the experiment you mentioned I noticed that stations that did provide an ANTAB file extended their frequency coverage by half a BBC sideband at both sides of the range. So I added that to the nominal ANTAB file too in version 0.12.0. If this is too much, let me know.
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