Документ взят из кэша поисковой машины. Адрес оригинального документа : http://xmm.vilspa.esa.es/calibration/documentation/epic_cal_meetings/200502/ek_pntimingmode.pdf Дата изменения: Fri May 16 13:28:53 2014 Дата индексирования: Wed Apr 13 13:30:25 2016 Кодировка:

pn Timing mode: - what causes the brighter line?

Eckhard Kendziorra, Marcus Kirsch 01.02.2005


image of point source in RAWX, RAWY

bright line, why?


Zoom of feature ? Shows up only for bright point sources ? Problem in offset map? no common mode? no integration time? yes

RAWY ~ 19


Timing sequence measured with engineering model at IAAT ? QM boards of master sequencer, SECOM and CPU used ? on board (PROM) S/W for EPEA V5.14 - but no changes in mode set-up since ? command sequence to set up Timing mode copied from flight procedures ? only one CCD (200 x 64 pixel) - same as in flight


Screen shot from oscilloscope
Start of frame

PHI-Pulse

New line (INIT)

TIMING


CCD readout in Timing Mode (M.K.)
CAMEX CAMEX CAMEX
Line 20 - 39 Line 0 - 19

1st readout 2nd readout

10th readout

Pseudo (macro) CCD:

64 x 200 macro pixel, contains information from 10 real CCD readouts

Line 180- 199


Result of hiccup
? First ,,macroline" contains only ONE CCD line, set to BAD anyhow ? ,,Integration time" during readout of second macroline is (29 + 23) µs integration time for point source at RAWY = 189 is factor 1.8 longer than for all other macrolines macroline no. 19 gets factor 1.8 higher flux from point source


Corrective actions
None, ? error cannot be corrected on board, ? no need for S/W modification on ground


Effect on science None, as long as integration time for spectra and light curves = 5.9 ms Possibly for pulse phase spectroscopy with bin sizes below 5.9 ms, but only if pulse period = beat frequency of frame time - leave as is, - mention feature in Users Hand Book


How the back contact voltage is monitored

HV converter 280 kO 1 mV 280 kO
ADC

to CCD

~1V

CCD

8 bit ADC 5.6 kO

EPCE average of 4 readings