1. Metis On-Board SW overview

2. OBSW overview Summary Metis OBSW structure Operative Modes
Acquisition Schemes
On-board data processing chains
MPPU & CPC
UV Detector
Visible Detector

3. OBSW main tasks
METIS functionalities are realized trough the OBSW exploiting the HW resources.
MPPU & CPC
Handle TM/TC communication with Solar Orbiter
Manage and control METIS detectors
Manage and control METIS IOM mechanisms
Manage thermal control of METIS
Monitor METIS status and handle FDIR
Execute scientific operational sequences
Perform scientific data processing and compression
UV Detector
Visible Detector

4. On Board Software Structure
METIS OBSW consists of two executable, both running on the MPPU CPU board, plus a set of HW procudures.
Main OBSW modules
The Boot Loader Software executable
stored on the PROM memory
loads the Instrument Management Software executable from MRAM (non volatile memory) to RAM memory
starts its execution
In case no SW image could be loaded in RAM, it enters the Software Maintenance Mode permitting SW patching and SW Images configuration.
The Instrument Management Software executable
stored in MRAM memory
loaded in RAM memory and started by the Boot-loader
implements all the instrument management functionalities necessary for the mission
HW implemented Software
(part of) Data processing
OBSW Executables
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5. Metis Operative Modes MODE Description OFF Metis unpowered POWER UP
entered whenever power is fed
BOOT
Check and load the SW image
SW Maintenance /
Boot SW Maintenance
dedicated to perform SW images patch and configuration, and memory management.
SAFE/STAND-BY
idle mode where METIS keeps its basic survival functionalities, delivers basic HK telemetry and waits for operations. It is also a SAFE mode where the instrument will fall as a consequence of FDIR intervention.
SETUP AND CONFIGURATION
intended for configuration of all operative parameters, diagnostics and preparation of observations.
DIAGNOSTIC
intended as troubleshooting mode
OPERATIONAL
normal mode of operations. Observation sessions takes place as driven by telecommands coming from the platform.

6. Metis Nominal Operations
Power Applied

7. Metis Nominal Operations
Power Applied
Successful Boot

8. Metis Nominal Operations
Power Applied
Successful Boot
Instrument in SAFE Mode

9. Metis Nominal Operations
Power Applied
Successful Boot
Instrument in SAFE Mode
Transition to SETUP
Subsystems power on
Instrument common configuration

10. Metis Nominal Operations
Power Applied
Successful Boot
Instrument in SAFE Mode
Transition to SETUP
Subsystems power on
Instrument common configuration
Transition to OPS
Configure Acquisition
Configure PMP
Configure Compression
START ACQUISITION

11. Metis Acquisition Schemes
The VL and UV channels can be operated in different modes, depending mainly by:
Different on board processing
Different sub-system operations
VLDA
Polarised
Acquisition
Polarised Brightness - pB
The different operations provide 6 nominal acquisition schemes, 3 for the VL and 3 for the UV channel.
Actually 3 more schemes exists:
VL-Temporal Noise
UV-Temporal Noise
UV Photon Counting – Test Mode
but these modes are not used in Nominal operations and are not described here.
Total Brightness - tB
Fixed Polarisation
UVDA
Photon
Counting
Photon List
Accumulation
Analog

12. VLDA Processing: Polarised Acquisition
CME monitoring
Spacecraft
light curve
Sun Disk Monitoring
data compression
VLDA
Read
Re-ordering
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization 1 3 2 4 5 8
Log Matrix
exposure
frames
corrected
frames
Every single frame will be Readout, Reordered.

13. VLDA Processing: Polarised Acquisition
CME monitoring
Spacecraft
light curve
Sun Disk Monitoring
data compression
VLDA
Read
Re-ordering
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization 1 3 2 4 5 8
Log Matrix
exposure
frames
corrected
frames
A Cosmic Ray Scrub will be applied to remove cosmic rays from METIS images;
The algorithm compares pixels having the same coordinates belonging to 2 images sequentially acquired in the same configuration. If the pixels show very different signals, the pixel having the maximum value is replaced by the pixel with the minimum value.
The pixels that have been modified are recorded into a Log Matrix.

14. VLDA Processing: Polarised Acquisition
CME monitoring
Spacecraft
light curve
Sun Disk Monitoring
data compression
VLDA
Read
Re-ordering
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization 1 3 2 4 5 8
Log Matrix
exposure
frames
corrected
frames
The CME detection algorithm operates on the VL frames. The implemented algorithm computes the running difference of consecutive images and looks for abrupt changes caused by possible arising of transient bright events.
METIS field of view is split in 8 sectors, the signal resulting by averaging the pixels belonging to each sector is then monitored looking for abrupt changes caused by possible arising of transient bright events.
The temporal series of the computed values is then sent to ground as a light curve.
The same algorithm is used to monitor if the Sun disk is entering into the Metis FOV.

15. VLDA Processing: Polarised Acquisition
CME monitoring
Spacecraft
light curve
Sun Disk Monitoring
data compression
VLDA
Read
Re-ordering
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization 1 3 2 4 5 8
Log Matrix
exposure
frames
corrected
frames
For VLDA measurements, every image is obtained by averaging in memory several frames acquired with the polarimeter in the same condition and using the same Detector Integration Time (DIT). s1 S s2 …
sNDIT
Detector Integration Time (DIT) 1 ÷ 600 s
NDIT within 1 ÷ 64
NDIT

16. VLDA Processing: Polarised Acquisition
CME monitoring
Spacecraft
light curve
Sun Disk Monitoring
data compression
VLDA
Read
Re-ordering
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization 1 3 2 4 5 8
Log Matrix
exposure
frames
corrected
frames
Each VL image provides a data quality hint supplying the pixels spatial variance and the average signal computed on a proper sub-array of the final (i.e. after co-adding) raw image. The info are gathered in the data header.
Noise computation areas

17. VLDA Processing: Polarised Acquisition
CME monitoring
Spacecraft
light curve
Sun Disk Monitoring
data compression
VLDA
Read
Re-ordering
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization 1 3 2 4 5 8
Log Matrix
exposure
frames
corrected
frames
Finally an algorithm based on CCSDS-123, optimized for solar corona images, is applied to maximize the scientific return.
Main characteristics:
lossless and lossy compression in one single package;
Re-mapping to produce a ‘radial’ image to exploit the geometry of solar corona enhancing compression
Radial binning
Uniform and radially variably binning possible
Prediction on previous images
Area 1
Area 2
Area 3
Area 4

18. Polarized Brightness Total Brightness

19. VLDA Processing: Fixed Polarization (FLUCTS)
Read
Re-ordering
Pre-filter …
Up to 64 images
Spacecraft
data compression
Radialization
Masking
Binning
Compression
TM Packetization
In this acquisition scheme the VL detector acquires continuously the commanded frames with a given detector integration time. This acquisition scheme has been created in order to perform acquisitions at high rate.
A minimum detector integration time of 1s can be set and a maximum number of 64 frames can be acquired. At 1s detector integration time and for 64 frames, the total acquisition time is of about 11 minutes, including processing time.
Every single frame will be Readout, Reordered. A possible pre-filter can be applied to each incoming frame in order to reduce the number of pixels to be stored on board. The pre-filter function can apply a uniform 2x2 binning or a radial masking.
All frames are acquired by keeping the polarisation angle at the same fixed position.
Eventually, the individual frames are compressed and delivered to ground.

20. VLDA Processing: Fixed Polarization (FLUCTS)
DIT ≥ 1s
Max expected duration < 11 minutes

21. UVDA Photon Counting Unit
The main tasks of the Photon Counting Unit :
Offset correction: the pixels values as acquired from the UVDA are corrected by subtracting an offset which depends on the x,y coordinates.
Through a proper system of delays, the system will generate 3x3 pixel windows that sweep dynamically the whole matrix at the pace of the pixel clock (12 MHz).
The processing system will perform the following tasks on each 3x3 window: 1 3 2 4 5 8
checking, according to appropriate discrimination, for the presence of a charge distribution representing a photon event;
computing the centroid coordinates;
computing the amplitude of the event, i.e. the integrated signal on the 3x3 window.
Photon
List
Spacecraft
Photon Counting Unit
UVDA
Offset Correction
Photon Detection
Photon List Generation
TM Packetization
Photons
Matrix
Accumulation Matrix
Compression
TM Packetization

22. Photon Counting: Photon list - Accumulation
The list of events are then handled differently for the 2 sub-cases:
Photon Counting – Photon List:
No processing on the list of events, the data stream is packetized and sent to the S/C
Photon Counting – Accumulation:
An 1k x 1k event matrix is built. The pixel of coordinates (x,y) contains the number of events registered for that position on the detector. An energy vector is also produced reporting the distribution energy of the set of the detected events.
Photon
List
Spacecraft
Photon Counting Unit
UVDA
Offset Correction
Photon Detection
Photon List Generation
TM Packetization
Photons
Matrix
Accumulation Matrix
Compression
TM Packetization

23. UVDA – Analog Mode Spacecraft Log Matrix
Every single frame is Readout. A first average is computed by the Pre-sum module.
A Cosmic Ray Scrub is applied to remove cosmic rays from METIS images; it provides also the Log Matrix of the pixels that have been modified
The final exposure is obtained by averaging in memory several acquisitions having the same Detector Integration Time (DIT).
As for the VL case, also the UV channel provides a data quality hint supplying the pixels spatial variance and the average signal computed on a proper sub-array of the final (i.e. after co-adding) raw image coded in the data header.
Finally a customized compression algorithm is applied to maximize the scientific return.
data compression
Spacecraft
UVDA
Read
PreSum
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization
Analog
Mode
acquisition
Corrected
acquisitions
exposure 1 3 2 4 5 8
frames
Log Matrix

24. Photon List Generation
CME monitoring
Spacecraft
Polarised
Acquisition scheme
Sun Disk Monitoring
light curve
Read
Re-ordering
C.Rays
& SEP
Co-adding
Statistics
data compression
Radialization
Masking
Binning
Compression
TM Packetization
VLDA
frame
corrected
frame 1 3 2 4 5 8
exposure
Read
Re-ordering
Pre-filter
VL-FP
Acquisition scheme …
data compression
Read
PreSum
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization
Analog
Mode
UVDA 1 3 2 4 5 8
Photon
List
frame
acquisition
exposure
Photon
Counting
Mode
Offset Correction
Photon Detection
Photon List Generation
TM Packetization
Photon Counting Unit
Photons
Matrix
Accumulation Matrix
Compression
TM Packetization

25. Photon List Generation
CME monitoring
Spacecraft
Polarised
Acquisition scheme
Sun Disk Monitoring
light curve
Read
Re-ordering
C.Rays
& SEP
Co-adding
Statistics
data compression
Radialization
Masking
Binning
Compression
TM Packetization
VLDA
frame
corrected
frame 1 3 2 4 5 8
exposure
Read
Re-ordering
Pre-filter
VL-FP
Acquisition scheme …
data compression
Read
PreSum
C.Rays
& SEP
Co-adding
Statistics
Radialization
Masking
Binning
Compression
TM Packetization
Analog
Mode
UVDA 1 3 2 4 5 8
Photon
List
frame
acquisition
exposure
Photon
Counting
Mode
Offset Correction
Photon Detection
Photon List Generation
TM Packetization
Photon Counting Unit
Photons
Matrix
Accumulation Matrix
Compression
TM Packetization

26. Metis On-Board SW overview