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 70um 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.

Analysis

Five DCEs were collected at each of 3 Voffset settings, first at the 70um primary dark position, then at the secondary 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-126. For the A-side, readout 4,4 is always starting at 0, so I ignored it in this analysis and calculated minimum and median values for the other 15 readouts. 
                                          B-side     A-side
Filename                                 med  min   med  min   VoffsetA   B
SCANPOS 102:

MIPS.2.0006929920.0000.0000.01.mipl.fits 4375 1240  2992 1171    0xCA    0xA0
MIPS.2.0006929920.0000.0001.01.mipl.fits 4373 1253  3015 1168    0xCA    0xA0
MIPS.2.0006929920.0000.0002.01.mipl.fits 4351 1261  2927 1143    0xCA    0xA0
MIPS.2.0006929920.0000.0003.01.mipl.fits 4367  991  3007 1179    0xCA    0xA0
MIPS.2.0006929920.0000.0004.01.mipl.fits 4333 1279  2988 1157    0xCA    0xA0

MIPS.2.0006929920.0001.0000.01.mipl.fits  511    0  4255 2456    0xC0    0xBE
MIPS.2.0006929920.0001.0001.01.mipl.fits  507    0  4251 2464    0xC0    0xBE
MIPS.2.0006929920.0001.0002.01.mipl.fits  519    0  4267 2451    0xC0    0xBE
MIPS.2.0006929920.0001.0003.01.mipl.fits  471    0  4271 2451    0xC0    0xBE
MIPS.2.0006929920.0001.0004.01.mipl.fits  511    0  4275 2445    0xC0    0xBE

MIPS.2.0006929920.0002.0000.01.mipl.fits    0    0  1697    0    0xD4    0xD2
MIPS.2.0006929920.0002.0001.01.mipl.fits    0    0  1701    0    0xD4    0xD2
MIPS.2.0006929920.0002.0002.01.mipl.fits    0    0  1694    0    0xD4    0xD2
MIPS.2.0006929920.0002.0003.01.mipl.fits    0    0  1734    0    0xD4    0xD2
MIPS.2.0006929920.0002.0004.01.mipl.fits    0    0  1731    0    0xD4    0xD2

SCANPOS 103:

MIPS.2.0006929920.0003.0000.01.mipl.fits    0    0  1735    0    0xD4    0xD2
MIPS.2.0006929920.0003.0001.01.mipl.fits    0    0  1730    0    0xD4    0xD2
MIPS.2.0006929920.0003.0002.01.mipl.fits    0    0  1730    0    0xD4    0xD2
MIPS.2.0006929920.0003.0003.01.mipl.fits    0    0  1704    0    0xD4    0xD2
MIPS.2.0006929920.0003.0004.01.mipl.fits    0    0  1694    0    0xD4    0xD2

MIPS.2.0006929920.0004.0000.01.mipl.fits  543    0  4269 2457    0xC0    0xBE
MIPS.2.0006929920.0004.0001.01.mipl.fits  528    0  4282 2463    0xC0    0xBE
MIPS.2.0006929920.0004.0002.01.mipl.fits  559    0  4275 2459    0xC0    0xBE
MIPS.2.0006929920.0004.0003.01.mipl.fits  542    0  4293 2456    0xC0    0xBE
MIPS.2.0006929920.0004.0004.01.mipl.fits  442    0  4272 2462    0xC0    0xBE

MIPS.2.0006929920.0005.0000.01.mipl.fits    0    0  2978 1167    0xCA    0xC8
MIPS.2.0006929920.0005.0001.01.mipl.fits    0    0  2998 1171    0xCA    0xC8
MIPS.2.0006929920.0005.0002.01.mipl.fits    0    0  3004 1167    0xCA    0xC8
MIPS.2.0006929920.0005.0003.01.mipl.fits    0    0  3010 1172    0xCA    0xC8
MIPS.2.0006929920.0005.0004.01.mipl.fits    0    0  2990 1174    0xCA    0xC8

For the following 3 files, here are the pixel-by-pixel ramp starting points
for the lower left readout (7,7).
MIPS.2.0006929920.0000.0002.01.mipl.fits
MIPS.2.0006929920.0001.0002.01.mipl.fits
MIPS.2.0006929920.0002.0002.01.mipl.fits

         0xA0                    0xBE                     0xD2
 6695 2996 4352 2176     2848    0  576    0       305    0    0    0
 8488 3328 4741 1927     4609    0  907    0      2016    0    0    0
 6129 2880 4481 2315     2305    0  645    0         0    0    0    0
 9985 3607 4864 2293     6123    0  993    0      3597    0    0    0
 6131 2887 4391 2383     2289    0  515    0         0    0    0    0
 8101 3168 4451 1856     4185    0  593    0      1651    0    0    0
 6136 2592 4297 2091     2341    0  408    0         0    0    0    0
22073 6281 5376 2827    18260 2645 1335    0     15616    0    0    0
It is clear from these data that the gain in DN/DAC count is the same for each pixel in the readout, as expected. Visual inspection of the data shows that the other 15 readouts on side B of the array have offsets consistent with those of this readout. The gain for both the A-side and the B-side of the array is -128 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 were: median=2670+/-80, minimum=1910+/-130. The A-side measured values of median=3000, minimum = 1170 are noticeably different from what was expected based on five CTA measurements made with CE1 during ground testing.

Conclusions

The gain of the offset DAC is -128 DN/DAC count. The nominal offset DAC setting of 0xCA is fine for the A-side of the array. If the anomalous offset pattern problem persists on the B-side of the array, the offset DAC will need to be maintained at 0xA0 to ensure that all pixels are on-scale. Excluding the first pixel in the readout, the largest starting points for other pixels on the B-side of the array will be about 10000 DN, which is about 8000 DN above the lowest pixels. The consequence is a roughly 12% loss in dynamic range. The current A-side minimum starting point of 1170 DN is low enough that we need to look at data ramps and see if negative spikes are a common occurrence. If so, we might wish to change the offset to something lower than 0xCA to bring the array further on-scale.

Output and Deliverable Products

None

Actions Following Analysis

None