[daip] SPECR + UVFRE: Combining VLA datasets with different frequency axes.

[Eric Greisen]

On 06/22/2017 03:40 PM, Nissim Kanekar wrote:
>
> Hi Eric,
>
> I've run into a problem with combining two VLA datasets with different
> frequency axes, using SPECR and UVFRE in 31DEC17. One dataset is from
> the VLA and has a bandwidth of 3.125 MHz and 128 channels (i.e. channel
> resolution of 24.41 kHz), while the other is from the JVLA and has a
> bandwidth of 4 MHz and 256 channels (i.e. channel resolution of 24.41
> kHz). The bands are also centred at different frequencies.
>
> I first used SPECR with NPOINTS 160 to convert the JVLA dataset to a
> channel resolution of 25 kHz, and then SPECR with NPOINTS 125 to convert
> the VLA dataset to the same resolution. The VLA.SPECR dataset has a
> frequency of 1418.4974 MHz at channel 63 and 125 channels. I then SPLIT
> the JVLA.SPECR dataset to produce a dataset with 125 channels and 25 kHz
> resolution, and with a central frequency of 1418.8454 MHz (within half a
> channel of the value in the VLA dataset). And then ran UVFRE to regrid
> the JVLA.SPECR dataset to the VLA.SPECR dataset. The JVLA.UVFRE file now
> appears to have the same frequency structure as the VLA.SPECR dataset,
> i.e. 125 channels, with a frequency of 1418.4974 MHz at channel 63, and
> a channel resolution of 25 kHz. However, when I next run DBCON to
> combine the two files (keeping the VLA.SPECR file first and the
> JVLA.UVFRE file second), I get the following error message:
>
> JEEVES> DBCON1: Copied WX file from vol/cno/vers  1    8   1 to  1   11   1
> JEEVES> DBCON1: Copied OF file from vol/cno/vers  1    8   1 to  1   11   1
> JEEVES> DBCON1: Copied FO file from vol/cno/vers  1    8   1 to  1   11   1
> JEEVES> DBCON1: TABINI: KEY COUNTS     51     51 OR COLS     13     11
> DON'T MAT
> JEEVES>         CH
> JEEVES> DBCON1: DBCAPP: ERROR    1 OPENING INPUT TABLE
> JEEVES> DBCON1: Appears to have ended successfully
> JEEVES> DBCON1: jeeves 31DEC17 TST: Cpu=     14.5  Real=     15  IO=
> 12065
>
>
> The DBCON output file now only contains the first datafile (the VLA
> dataset), when plotted with VPLOT.
>
> If I try changing the order in DBCON, with the JVLA.UVFRE file first and
> the VLA.SPECR dataset second, I get a different error:
>
>
> JEEVES> DBCON1: Task DBCON  (release of 31DEC17) begins
> JEEVES> DBCON1: WARNING: COMBINING VISIBILITY DATA WITH DATAOF UNKNOWN TYPE
> JEEVES> DBCON1: RA does not match, will shift second
> JEEVES> DBCON1: DEC does not match, will shift second
> JEEVES> DBCON1: Create ESO 461-36  .DBCON .   1 (UV)  on disk  1  cno   11
> JEEVES> DBCON1: Copied AN file from vol/cno/vers  1    7   1 to  1   11   1
> JEEVES> DBCON1: Copied AN file from vol/cno/vers  1    4   1 to  1   11   2
> JEEVES> DBCON1: DBMNGL: at output record     50000
> .....
> JEEVES> DBCON1: DBMNGL: at output record   2050000
> JEEVES> DBCON1: Copied WX file from vol/cno/vers  1    7   1 to  1   11   1
> JEEVES> DBCON1: DBCAPP: INPUT TABLES DO NOT MATCH
> JEEVES> DBCON1: Appears to have ended successfully
>
> This time, the DBCON output appears to contain only the JVLA.UVFRE data
> (when plotted with VPLOT).
>
> I'm not sure whether I'm making a mistake when combining the two files,
> or if there's some sort of a bug in UVFRE. Do you happen to know what's
> going on?
>
Maybe you are making a mistake with VPLOT - do you have two subarrays? 
(Two AN tables on the output).  VPLOT will only display 1 subarray at a 
time usually number 1.  I don't have time to chase these errors right 
now but I am not surprised if EVLA and old VLA tables do not match entirely.

Eric Greisen