[Sls-rfm] CCSDS RFM WG AI_20-01 (PN register convention)

[Enrico.Vassallo at esa.int]

Dear All,

please find my response as both ESA representative in RFM WG and as RFM WG 
chair to the action item:

AI_20-01        Report about the PN register proposal in CS_20-03, the 
possible need to have a similar standard representation and, in case, the 
preferred way forward

Input paper CS_20-03 recommends changes to the following RFM WG books: 

1) 415.1-B-1, dated 2011

2) 415.1-G-1, dated 2013

3) 401.1-B REC 2.5.7B-white

Document CS_20-03 proposes to adopt the Matlab convention. 
Main differences between what's in documents 1-3 and the proposal in 
CS_20-03 is the fact that in the pictures the output register is numbered 
N in 1-3 as opposed to 0 in the proposal; additionally, the first register 
is numbered 1 (zero is not used in 1-3).

Documents 1-2-3 are consistent. 
Document 2 (green book) provides in page 3-3 a detailed explanation of the 
convention used, addresses different conventions in literature, and links 
the drawing of the picture with resulting equations and polynomials. This 
info is in sections 3.4 to 3.8.
Document 1 (blue book) provides some explanation of the convention used in 
section 1.6.2.
Document 3 has two pictures in Annex A with no explanation while the 
polynomials are in the main body of the recommendation. 

Documents 1-2 were mainly NASA's (GFSC) inputs aimed at extending the SNIP 
agreement (latest version from 1998) between ESA, NASA and NASDA (now 
JAXA) for which the latest version dates November 1998 to encompass more 
CCSDS agencies.

The change request in CS_20-03 would entail editing the following number 
of pictures: 5 (doc 1) + 10 (doc 2) + 2 doc (3) = 17 in addition to 
adjusting the related text.

Given that documents 1 and 2 have been used for almost a decade with no 
report of implementation mistakes by ESA equipment developers, and the 
changes in CS_20-03 would result in full disagreement with the SNIP 
document, it is proposed NOT to adopt the Matlab convention for the RFM WG 
books. However, concerning the draft DDOR recommendation 2.5.7B under 
development, some explanation could be added as done in 1 (or even in 2.)

It is possible that other WGs of the SLS area may prefer a different 
approach for their books but as long as the recommendations of the same WG 
are consistent, I do not see this as an issue.

Best Regards, Enrico 


This message is intended only for the recipient(s) named above. It may contain proprietary information and/or
protected content. Any unauthorised disclosure, use, retention or dissemination is prohibited. If you have received
this e-mail in error, please notify the sender immediately. ESA applies appropriate organisational measures to protect
personal data, in case of data privacy queries, please contact the ESA Data Protection Officer (dpo at esa.int).

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.ccsds.org/pipermail/sls-rfm/attachments/20200622/40cba921/attachment.htm>