Contact Stansberry - "; echo " there is a problem w/ your write-up.\n"; return ; } $row = mysql_fetch_array($result); $title = $row["title"]; $princ = $row["principal"]; $deputy= $row["deputy"]; $campn0 = $row["campn0"]; $aorkeys = $row["aorkeys"]; // get real name of principal, deputies $princ = ioc_get_person($princ); $princ = $princ[0]; $deps = explode(",",$deputy); foreach ($deps as $depty) { $depty = trim($depty); $depty = ioc_get_person($depty); $depty = $depty[0]; $depty = explode(",",$depty); $depty = $depty[0]; // last names only $deplist[] = $depty; } $deplist = implode(", ", $deplist); $caid = sprintf("%03d",$caid); $file = "mips-".$caid.$campn.".analysis.php"; // END PHP. ?> <? echo "MIPS-$caid, Campaign $campn IOC/SV Analysis"; ?>

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Task Outcome Summary

Abstract

The goal of this task was to determine the optimal Voffset value for the 160um array. The criteria are to provide the largest possible dynamic range without ever starting any of the data ramps at the bottom rail of the A-D converter. An error was made in the IER such that the Voffset values were left at a DAC setting of 0xD2. This did not bring any of the pixels off-scale, so no harm was done to the subsequent 160um tests in this campaign. However, the 70um Voffsets were set to 0xC8, which differs from the nominal 0xCA for side A (260 DN) and 0xA0 for Side B (5160 DN). This resulted in most of the pixels on side B of the 70um array being off-scale by a large margin for the rest of the campaign.

Analysis

Five DCEs were collected at each of 3 Voffset settings at the 160um dark position. For each DCE, the median and minimum ramp starting points were determined. The results are discussed below.

Results

The following are the median and minimum starting points for each of the DCEs collected in the task MIPS-127. Readout 3 always read zero so I ignored it when determining the minimum value on the A-side of the array. 
                                          A-side     B-side
Filename                                 med  min   med  min   VoffsetA   B
SCANPOS 104:

MIPS.3.0007137536.0000.0000.01.mipl.fits 4159 2986  4500 2726    0xC8    0xC8
MIPS.3.0007137536.0000.0001.01.mipl.fits 4144 2950  4492 2699    0xC8    0xC8
MIPS.3.0007137536.0000.0002.01.mipl.fits 4138 2930  4479 2766    0xC8    0xC8
MIPS.3.0007137536.0000.0003.01.mipl.fits 4118 2916  4508 2699    0xC8    0xC8
MIPS.3.0007137536.0000.0004.01.mipl.fits 4093 2952  4576 2719    0xC8    0xC8

MIPS.3.0007137536.0001.0000.01.mipl.fits 5457 4223  5790 4040    0xBE    0xBE
MIPS.3.0007137536.0001.0001.01.mipl.fits 5437 4218  5759 4002    0xBE    0xBE
MIPS.3.0007137536.0001.0002.01.mipl.fits 5407 4170  5871 3973    0xBE    0xBE
MIPS.3.0007137536.0001.0003.01.mipl.fits 5443 4351  5778 4000    0xBE    0xBE
MIPS.3.0007137536.0001.0004.01.mipl.fits 5416 4207  5759 3965    0xBE    0xBE

MIPS.2.0007137536.0002.0000.01.mipl.fits 2819 1704  3326 1407    0xD2    0xD2
MIPS.3.0007137536.0002.0001.01.mipl.fits 2891 1642  3231 1353    0xD2    0xD2
MIPS.3.0007137536.0002.0002.01.mipl.fits 2840 1684  3196 1431    0xD2    0xD2
MIPS.3.0007137536.0002.0003.01.mipl.fits 2856 1661  3180 1480    0xD2    0xD2
MIPS.3.0007137536.0002.0004.01.mipl.fits 2842 1654  3184 1431    0xD2    0xD2

The gain for both the A-side and the B-side of the array is -129 +/- 1 DN/DAC count.

Ground testing indicated a gain of roughly -130 DN/DAC count, fully consistent with these results. The expected values for the ramp starting points for Voffset = 0xC8 were: median=4050+/-50, minimum=2600+/-100. The values measured in this campaign were: median=4320, minimum = 2720. These starting points are within the range of values seen in ground testing.


Conclusions

The gain of the offset DAC is -129 DN/DAC count. The nominal offset DAC setting of 0xC8 gives a 2700 DN cushion to prevent pixels from going off-scale. This is sufficient to prevent problems from negative crosstalk spikes, which have maximum observed amplitudes of 2000 DN, and post-saturation recovery dips, which have maximum observed amplitudes of 1000 DN. Readout 3 is far enough off-scale that there is no point in adjusting offset voltages to try to recover it.

Output and Deliverable Products

None

Actions Following Analysis

None