[SLS-CC] [EXTERNAL] Technical corrigendum for SCCC pseudo-randomizer

[Andrea Modenini]

HI all,
Please be informed that the corrigendum was sent for CESG approval.

Andrea

Ph.D. Andrea Modenini
TT&C Communications Systems Engineer
E2E systems communication Section (TEC-SET)
European Space Agency, ESTEC
Keplerlaan 1, PO Box 299
2201AZ Noordwijk, The Netherlands
andrea.modenini at esa.int<mailto:andrea.modenini at esa.int> | www.esa.int<http://www.esa.int/>
T +31 6 484 56 527

From: SLS-CC <sls-cc-bounces at mailman.ccsds.org> On Behalf Of Andrea Modenini via SLS-CC
Sent: 26 January 2026 08:52
To: kenneth.s.andrews <kenneth.s.andrews at jpl.nasa.gov>
Cc: sls-cc at mailman.ccsds.org
Subject: Re: [SLS-CC] [EXTERNAL] Technical corrigendum for SCCC pseudo-randomizer

Hi Ken,
Good point, I will add also 8.2.2 changes as you proposed.

For the 255-bit pseudo-randomizer, your assessment matches ours: the SCCC uses a PL randomizer, so the short randomizer is still acceptable.
The only point of interest that we saw in having the PN17 also for SCCC is for harmonization (e.g., we are developing in ESA a TT&C transponder, that does both standard TM and SCCC, and a single pseudo-randomizer simplifies the specification with the OBC and on-board Mass Memory)

In summary, for the time being  the 255-bit is fine for ESA, but we may propose in future to update to PN17 if the need better materializes,

Andrea
Ph.D. Andrea Modenini
TT&C Communications Systems Engineer
E2E systems communication Section (TEC-SET)
European Space Agency, ESTEC
Keplerlaan 1, PO Box 299
2201AZ Noordwijk, The Netherlands
andrea.modenini at esa.int<mailto:andrea.modenini at esa.int> | www.esa.int<http://www.esa.int/>
T +31 6 484 56 527

From: Andrews, Kenneth S (US 332B) <kenneth.s.andrews at jpl.nasa.gov<mailto:kenneth.s.andrews at jpl.nasa.gov>>
Sent: 24 January 2026 04:19
To: Andrea Modenini <Andrea.Modenini at esa.int<mailto:Andrea.Modenini at esa.int>>
Cc: sls-cc at mailman.ccsds.org<mailto:sls-cc at mailman.ccsds.org>
Subject: Re: [EXTERNAL] [SLS-CC] Technical corrigendum for SCCC pseudo-randomizer

Andrea, and all,

I agree that the corrigendum is necessary to preserve the meaning of the standard, so you have my support.

I notice that following paragraph 8.2.2, Note 1 says, “The method for ensuring sufficient transitions is to exclusive-OR each bit of the codeblock, codeword, or Transfer Frame with a standard pseudo-random sequence.”  It looks like this was copied from the 131.0-B book, but it is confusing here because only the Transfer Frame option is applicable.  I’ll suggest striking the other options so that it says, “The method for ensuring sufficient transitions is to exclusive-OR each bit of the Transfer Frame with a standard pseudo-random sequence.”  While submitting a corrigendum, it might be worth making this change as well.

Just thinking aloud, we should consider if the length-255 pseudo-randomizer is still appropriate in this standard, or if it should be updated to the 17-cell randomizer as well.  Since randomization is applied before encoding in this standard, and there’s a somewhat complicated interleaver involved, I think the short randomizer continues to be acceptable.

-Ken

On Jan 21, 2026, at 5:36 AM, Andrea Modenini via SLS-CC <sls-cc at mailman.ccsds.org<mailto:sls-cc at mailman.ccsds.org>> wrote:

Dear all,
Wing/NASA noticed that the SCCC 131.2-B is still linking the TF pseudo-randomizer to the one of the 131.0-B.
Since version 5 of 131.0-B this is no longer correct, since SCCC refers to the 255-bit TF randomizer, while 131.0-B recommends the PN17 and the 255-bit exclusively for legacy systems.

As such, I would like to propose the technical corrigendum in attachment to CESG/CMC.
Can you please take a look by Friday 23rd  against the Blue Book<https://urldefense.us/v3/__https://ccsds.org/wp-content/uploads/gravity_forms/5-448e85c647331d9cbaf66c096458bdd5/2025/01/131x2b2.pdf?gv-iframe=true__;!!PvBDto6Hs4WbVuu7!K_ZInXLx3vZD6Pv039ykX9rZ-tOTLE3OJnPNxBPIzgpbcFG27cdprqtSWvAQ5kPmt_3jBRhdeOBRVZEsrdwgSScZ-1Ik9GI$>?

It really takes 10 minutes, but if you think that deadline is too short, feel free to contact me for an extension.


Regards,
Andrea


Ph.D. Andrea Modenini
TT&C Communications Systems Engineer
E2E systems communication Section (TEC-SET)
European Space Agency, ESTEC
Keplerlaan 1, PO Box 299
2201AZ Noordwijk, The Netherlands
andrea.modenini at esa.int<mailto:andrea.modenini at esa.int> | www.esa.int<https://urldefense.us/v3/__http://www.esa.int/__;!!PvBDto6Hs4WbVuu7!K_ZInXLx3vZD6Pv039ykX9rZ-tOTLE3OJnPNxBPIzgpbcFG27cdprqtSWvAQ5kPmt_3jBRhdeOBRVZEsrdwgSScZb5kbH2c$>
T +31 6 484 56 527

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