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Up: 13 Calibration G Products
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Description Parameter: section 4.3.1
Processing Level: SPD
Usage in processing: section 7.2.2
File Type: Binary Fits Table
Number of Records: 8
File Names: PSELNDR
It has been observed that the first few readouts of each integration ramp
do not increase in a linear way but can stay flat for a while or can even
decrease. The disturbance is due to the preceding reset and is a switch-on
effect of the integrator which is independent of the reset voltage level.
This effect is not related to the voltage dependent non-linearity for which
the corrections are stored in the Cal G linearisation files
(section 13.5)). The best correction method so far is to
discard these readouts. The number of readouts that should be removed is
a function of the number of readouts per ramp. The optimum values have been
determined in flight.
In total there are 8 records, each record gives the number of readouts to be discarded for a given NDR value. The record ordering is as follows:
| Record | number of non- | Record | number of non- |
| number | destructive readouts | number | destructive readouts |
| 1 | 0 | 5 | 15 |
| 2 | 1 | 6 | 31 |
| 3 | 3 | 7 | 63 |
| 4 | 7 | 8 | 127 |
Binary FITS table with record length 32. The record fields are:
Field Offset Number Type Description PP1SNDR 0 1 I*4 NDRs to discard for PHT-P1 PP2SNDR 4 1 I*4 NDRs to discard for PHT-P2 PP3SNDR 8 1 I*4 NDRs to discard for PHT-P3 PFILSNDR 12 1 I*4 Filler PSSSNDR 16 1 I*4 NDRs to discard for PHT-SS PSLSNDR 20 1 I*4 NDRs to discard for PHT-SL PC1SNDR 24 1 I*4 NDRs to discard for PHT-C100 PC2SNDR 28 1 I*4 NDRs to discard for PHT-C200
ISOPHOT Data Users Manual, Version 4.1, SAI/95-220/Dc