[SLS-OPT] ESA's comments on CNES O3K pink sheets
Geraldine.Artaud at cnes.fr
Mon Feb 22 11:32:37 UTC 2021
Thank you Nicolo for your comments.
I will try to prepare some inputs for the discussion tomorrow.
I wanted to upload a new version of the pink sheet on the cwe in the folder of the teleconference of 23/02/2020, but it seems that the ccsds website is experiencing some trouble this morning. I will try later in the day.
This new version includes modifications following the feedback we received from the OPT group and also from some industrials. They are mainly:
- Simplification of the slicer: no zero fill and no alignment of the slicer with the transfert frame. It comes from the will to reduce the complexity at the coding&synch layer. The link initialization and proper closure have to be handled by the transfer frame layer by beginning and closing a link with IDLE packets for example. For non deep-space applications, it is acceptable to have 1 second of idle packets transferred at the beginning and end of a link
- The LDPC chapter has be rewritten to make more comprehensive for non-coding experts. The steps to construct the matrix are now described, and the encoding process has also be added.
- Initialization sequence of the pseudorandomizer has been given to avoid misinterpretation
- The physical layer frame has been also modified. And it is a main update to improve the synchronization process. In the previous version, there was only one synchmarker per interleaved frame. This was a weakness since in case of loss of lock, the reacquisition time could be long. It is now proposed to insert a synchmarker at a constant spacing (defined as a managed parameter) to reduce the reacquisition time. The spacing can be set by the user to range from one codeword length (what is usually done in CCSDS standards) to a completed interleaved block (which is what I presented at the last telco). This new scheme appears to be much robust
The definitions of frame, subframe and idle fame are also more precisely written.
De : SLS-OPT <sls-opt-bounces at mailman.ccsds.org> De la part de Nicolo Mazzali (external)
Envoyé : mardi 16 février 2021 17:09
À : SLS-OPT at mailman.ccsds.org
Objet : [SLS-OPT] ESA's comments on CNES O3K pink sheets
In ESA we have spent some time to go through the O3K coding & sync proposal from CNES, and we find it very clear and comprehensive as it addresses the FEC coding, the channel interleaving, the VDR, and the framing in one single document.
We have reported our comments in the .doc file attached below: some are just clarifications, some others are meant to stimulate the discussion during the next meeting.
Modis for ESA - European Space Agency
Nicolò Mazzali, PhD
Communication Systems & Technologies Engineer
Telecommunications Section (TEC-ESC)
Radio Frequency Systems Division (TEC-ES)
Directorate of Technology, Engineering & Quality (D/TEC)
Keplerlaan 1, PO Box 299
NL-2200 AG Noordwijk, The Netherlands
nicolo.mazzali at esa.int<mailto:nicolo.mazzali at esa.int> | www.esa.int<http://www.esa.int/>
T +31 71 56 53215
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