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TGBT15A_915_137 - VPM Scale and Filter Tests
Test smaller fftshift values with 950 MHz IF module filter
Find better vegas.scale value for c0800x0512 coherent search
Incoherent modes: 0x555557ff, 0xaaaaabff, 0x555555ff, 0xaaaaaabf, 0x5555555f
Coherent modes: 0x55555fff, 0xaaaaafff
Verify Ray's patch for frequency precision in shared memory
Test Luke's new BOF file i0800x2048 mode
Session begins at 13:30
Editing vegas.conf with new i0800x2048 bof file
SB at 13:40 running i0800x2048 to test new BOF file
Didn't pick up new BOF file. Restarting VEGAS
Resubmitting at 13:47
Scan is #1
Scan successful, no obvious issues with BOF file.
Will move on to testing fftshift values. Going to stick with this mode. First will try 0x555557ff
Submitted SB at 13:58
Scan is #1
Levels are too low. Maybe I went in the wrong direction with the fftshift value?
Will try 0x55555555
Submitted at 14:02, scan #3
Data are maxing out as expected. Will lower vegas.scale to 5000 (50% reduction)
Submitted at 14:04, scan #4
No obvious effect. Lowering by 50% again to 2500
Submitted at 14:08, scan #5
Still too high, but not maxing out now. No sign of overflow artifacts. Will decrease scale by 50% again to 1250
Submitted at 14:13, scan #6
Data seem mostly OK, but will decrease scale by 70% to 875 to see how that looks.
Submitted at 14:18, scan #7
This looks pretty reasonable, but I'm curious to see what it looks like with an fftshift of 0xaaaaaaaa
Changed vegas.conf and dropping vegas.scale to 10
Submitted SB at 14:30, scan #8
Not enough power. Will increase vegas.scale to 100
Submitted SB at 14:32, scan #9
Still too low. Increasing back to 875, scan #10
Submitted SB at 14:34
Levels were OK but I think we are seeing the overflow artifacts again. Going back to 0x55555555
Will try some other incoherent 800 MHz modes.
Scans #11--16 will be i0800x0128 -- i0800x4096, with vegas.scale values of 875 or 437.5
Submitted SB at 14:43
Levels look OK on scans #11, 13, 15, with no obvious overflow artifacts
Levels too low on scans #12 (i0800x0256), 14 (i0800x1024), 16 (i0800x4096)
Obvious overflow in i0800x1024
Need to look at these data more carefully, but want to move on to the scale setting for the c0800x0512 mode.
SB for a c0800x0512 scan with vegas.scale = 400. No change to fftshift at this time.
SB submitted at 14:58, scan #18
Levels were still a bit low. Increase scale factor to 800
SB submitted at 15:14, scan #18
Levels look OK, but will compare with GUPPI
Still a bit low compared to GUPPI. Will increase scale to 1015
SB submitted for scan #19
This looks good.
Taking cal scan with this vegas.scale setting to see if it is also OK
In agreement with GUPPI
Ended a little early instead of trying to squeeze in the coherent mode fftshift tests. Restored vegas.conf to original settings and asked Ray or Joe to commit it.
Session ended at 15:50
The i0800x2048 BOF file seemed to be OK
The lower incoherent mode fftshift values seem usable, but more work is needed to understand why some modes show lots of overflow artifacts while others seem to show none.
The search-mode coherent mode scale for c0800x0512 now looks good. I need to do this exercise for other modes but should be able to use past tests as a guide.
Didn't get to test the coherent mode fftshift values.
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Topic revision: r3 - 2018-03-16,
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