Information relating to SCC calibration that effects
the accuracy of observation pointings (i.e. relevant data).
The following SCC Calibration Data is to be made available on an observation and revolution basis.
Regular/periodical calibrations:
- GYRO drift calibration
freq = daily
output = 4 bias values to be loaded on board (d1, d2, d3, d4)
the above values are used on board as follows:
Gyr(i)_corrected_output = sf(i)*Gyr(i) - d(i)
(where Gyr(i) is the "MACS bus" output (the one available in
TM), sf(i) are the GYRO scale factors: see below)
The results of the calibrations are available as ASCII file
containing for each record: time of generation of new data set as
result of the calibration, relevant calibrated values (4).
Note that the time of generation of the new data set (IPF) does not
correspond to the time of uplink on board of the values; since this
is a manual operation executed by the Spacon in the first available
time window after the end of the calibration, it is very difficult
for SCC to trace, via TC History the actual uplink time of each set
of data for all the revolutions (note also that the calibration is
not executed necessarily at a fixed time in the revolution).
- QSS/STR misalignment calibration
freq = daily
output = QDS quaternion
the above quaternion is used on ground to correct the target
quaternion before uplink of the pointing request commands
The results of the calibrations are available as ASCII file
containing for each record: time of start/end of the calibration,
time when the new QDS started to be applied, relevant calibrated
values (QDS quaternion) .
Non periodical calibrations:
- GYRO scale factor/misalignments calibration
freq = when required (once or twice per year)
output = 4 scale factor values (see above) and the GYRO projection
matrices (total of 36 coefficients) to be loaded on board
The results of the calibrations are available as ASCII file
containing for each record: time of generation of new data set as
result of the calibration, relevant calibrated values (4).
Note that the time of generation of the new data set (IPF) does not
correspond to the time of uplink on board of the values; it is not
difficult for SCC to provide also the times when the complete set of
new parameters has been uplinked on board.
- FSS (Fine Sun Sensor) misalignments calibration about Y-axis
freq =when required (once or twice per year)
output = 1 misalignment coefficient to be loaded on board (as part
of the FSS transfer function)
The results of the calibrations are available as ASCII file
containing for each record: time of generation of the coefficient,
relevant calibrated value (1). Note that the time of generation of the new
coefficient does not correspond to the time of uplink on board of the value;
it is not difficult for SCC to provide also the times when the new parameter
has been uplinked on board.
general info: the calibrated parameter has no relevance in the ISO
pointing accuracy : it is only used in "SLEW" mode to determine the
end of the slew when the FSS set-point (in this case the Sun Aspect
Angle) is met.
- FSS (Fine Sun Sensor) misalignments calibration about X-axis
freq = when required (once or twice per year)
output = 1 misalignment coefficient to be loaded on board (as part
of the FSS transfer function)
The results of the calibrations are available as ASCII file
containing for each record: time of generation of the coefficient,
relevant calibrated value (1).
Note that the time of generation of the new coefficient does not
correspond to the time of uplink on board of the value; it is not
difficult for SCC to provide also the times when the new parameter
has been uplinked on board.
general info: the calibrated parameter has relevance in the ISO
pointing accuracy (control of the roll angle, while in "POINTING"
sub-state is based on the FSS output).
- FSS (Fine Sun Sensor) misalignments calibration about Z-axis
freq = when required (once or twice per year)
output = 1 misalignment coefficient to be loaded on board (as part
of the FSS transfer function)
The results of the calibrations are available as ASCII file
containing for each record: time of generation of the coefficient,
relevant calibrated value (1). Note that the time of generation of
the new coefficient does not correspond to the time of uplink on
board of the value; it is not difficult for SCC to provide also the
times when the new parameter has been uplinked on board.
general info: the calibrated parameter has relevance in the ISO
pointing accuracy (control of the roll angle, while in "POINTING"
sub-state is based on the FSS output).
- STR (Star Tracker) misalignments calibration about X-axis
freq = when required (once or twice per year)
output = the misalignment angle about X-axis, which is then
transformed into two projection matrix coefficients (transformation
coefficient from STR reference frame to S/C reference frame); these
two last parameters are the ones to be actually loaded on board (as
SM-1/SM-2 coefficients)
The results of the calibrations are available as ASCII file
containing for each record: time of generation, STR misalignment
angle (1 value).
Note that the time of generation of the new coefficients does not
correspond to the time of uplink on board of the value; it is not
difficult for SCC to provide also the times when the new parameters
has been uplinked on board.
general info: the calibrated parameters have relevance in the ISO
pointing accuracy (while in "POINTING" sub-state the attitude
control about Y/Z axes is based on STR outputs).
- QSS bias/scale factor calibration
freq = executed only once during the mission in REV-10
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The following table gives the number of files, the average
file size, and the resulting total size in KB.
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| 1774 | 1.1 | 1825 |