<span style=" font-size:10pt;font-family:sans-serif">The approach proposed
by Greg is also consistent with the CRC specification in the the various
books for Space Data Link Protocols.</span>
<br><span style=" font-size:10pt;font-family:sans-serif">Also the CRC diagrams
- presenting "possible" implementations - are always called in
NOTES and they are then non normative while the polynomials are called
in normative clauses..</span>
<br><span style=" font-size:10pt;font-family:sans-serif">Being non normative,
in the OID Frames case there is no problem is showing TWO possible implementations
instead of a single one.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Regards</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Gian Paolo</span>
<br>
<br>
<br>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">From:
</span><span style=" font-size:9pt;font-family:sans-serif">"Kazz,
Greg J\(US 312B\) via SLS-SLP" <sls-slp@mailman.ccsds.org></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">To:
</span><span style=" font-size:9pt;font-family:sans-serif">"Sank,
Victor J. (GSFC-567.0)[SCIENCE SYSTEMS AND APPLICATIONS INC]" <victor.j.sank@nasa.gov>,
"Andrews, Kenneth S (US 332B)" <kenneth.s.andrews@jpl.nasa.gov></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Cc:
</span><span style=" font-size:9pt;font-family:sans-serif">"Kazz,
Greg J\(US 312B\) via SLS-SLP" <sls-slp@mailman.ccsds.org>,
"Fong, Wai H.\(GSFC-5670\)" <wai.h.fong@nasa.gov>, "Rodriguez,
Shannon\(GSFC-5670\)" <shannon.rodriguez-1@nasa.gov>, "Lee,
Wing-tsz\(GSFC-5670\)" <wing-tsz.lee-1@nasa.gov></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Date:
</span><span style=" font-size:9pt;font-family:sans-serif">01-06-21
15:16</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Subject:
</span><span style=" font-size:9pt;font-family:sans-serif">Re:
[Sls-slp] [EXTERNAL] Re: Your LFSR OID frame RIDs affecting USLP, TM, AOS
SDLPs</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Sent
by: </span><span style=" font-size:9pt;font-family:sans-serif">"SLS-SLP"
<sls-slp-bounces@mailman.ccsds.org></span>
<br>
<hr noshade>
<br>
<br>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Hi
Victor,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">The
resolution to adding the LFSR in TM, AOS, and USLP was to state the requirements
in the book, but then add <b>both</b> representations (Galois and Fibonacci)
into a new “non-normative” annex, since SLP WG blue books can’t provide
normative info about coding in our SLP blue books. “King Solomon approach”</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">In
the normative text in Chapter 4, the requirements are:</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<br><span style=" font-size:10pt;font-family:sans-serif">1.
</span><span style=" font-size:11pt;font-family:Calibri">The
TFDZ of an OID Transfer Frame shall be generated by use of a 32-cell Linear
Feedback Shift Register (LFSR) with polynomial 1 + D + D<sup>2</sup> +
D<sup>22</sup> +D<sup>32</sup>.</span>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">NOTE
– See Annex H which contain diagrams describing the LFSR.</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<br><span style=" font-size:10pt;font-family:sans-serif">2.
</span><span style=" font-size:11pt;font-family:Calibri">The
LFSR shall be initialized at device start-up with an all-one seed and shall
not be restarted. This requirement pertains exclusively to figure H-1 in
Annex H.</span>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">NOTE
– The first 10 bytes of the OID data pattern, in hexadecimal, are: FF
FF FF FF 6D B6 D8 61 45 1F ....</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">So
here are the diagrams that would go into a non-normative Annex in TM, AOS,
and USLP:</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><img src=cid:_4_0ECE70D40ECE6CC4004C40DDC12586E7 width=600 height=800 style="border:0px solid;"></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"><b>From:
</b>SLS-SLP <sls-slp-bounces@mailman.ccsds.org> on behalf of "Sank,
Victor J. (GSFC-567.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] via SLS-SLP"
<sls-slp@mailman.ccsds.org><b><br>
Reply-To: </b>"Sank, Victor J. (GSFC-567.0)[SCIENCE SYSTEMS AND APPLICATIONS
INC]" <victor.j.sank@nasa.gov><b><br>
Date: </b>Monday, May 31, 2021 at 7:10 PM<b><br>
To: </b>"Andrews, Kenneth S (US 332B)" <kenneth.s.andrews@jpl.nasa.gov><b><br>
Cc: </b>"Kazz, Greg J (US 312B)" <greg.j.kazz@jpl.nasa.gov>,
"Kazz, Greg J (US 312B) via SLS-SLP" <sls-slp@mailman.ccsds.org>,
"Fong, Wai H. (GSFC-5670)" <wai.h.fong@nasa.gov>, "Rodriguez,
Shannon (GSFC-5670)" <shannon.rodriguez-1@nasa.gov>, "Lee,
Wing-tsz (GSFC-5670)" <wing-tsz.lee-1@nasa.gov><b><br>
Subject: </b>[EXTERNAL] Re: [Sls-slp] Your LFSR OID frame RIDs affecting
USLP, TM, AOS SDLPs</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Ken,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
Did you have any comment about
the use of Fibonacci vs Galois for maximal pattern randomizers? If
so I think I missed it. As I remember Greg asked you to explain the
difference in the seeds for the two representations and said that both
representations would be shown in his book. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">My
question is general CCSDS standards. I would like to see a standard,
MatLab, IEEE, or whatever. For coding like BCH, that uses a polynomial
that is not irreducible (only 4 terms and it is “reducible”, g(x) = x^7+x^6
+ x^2 + 1 can be factored into (x + 1)(x^6 + x + 1)), I do not know if
a Fibonacci equivalent can generate the parity. Can it? If
it can, then for the following reason, I suggest that for any future CCSDS
book, we use Fibonacci for all shift registers diagrams.</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">A
maximal pattern register diagram can be either in the Fibonacci or Galois
type representation, as you have submitted for the long randomizer. I
am recommending Fibonacci be used in CCSDS books at least where maximal
and Gold codes are covered, since the output pattern is easily seen based
on the register contents. Since CCSDS does not recommend implementation,
the user is free to use Galois for implementation if that is their preference.
It would be nice if we can help the understanding of engineers
in the field that are not PhDs. The fact that you were asked to explain
why the seeds for the Fibonacci and Galois are different is telling.
</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
I do not agree with the comment
made by Enrico? or was it GP?, that since the BCH or other code in the
book used a Galois type format, that the maximal or Gold code representation
used should therefore be in Galois format. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
I would love to hear your comments.
(and can the BCH be shown in a Fibonacci format?) </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Thanks,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Victor
</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"><b>From:</b>
Sank, Victor J. (GSFC-567.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] <b><br>
Sent:</b> Monday, May 17, 2021 1:16 PM<b><br>
To:</b> Andrews, Kenneth S (JPL-332B)[JPL Employee] <kenneth.s.andrews@jpl.nasa.gov><b><br>
Cc:</b> Kazz, Greg J (US 312B) via SLS-SLP <sls-slp@mailman.ccsds.org>;
Kazz, Greg J (US 312B) <greg.j.kazz@jpl.nasa.gov><b><br>
Subject:</b> RE: Your LFSR OID frame RIDs affecting USLP, TM, AOS SDLPs</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Ken,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
Maximal pattern shift registers.
LFSR</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
CCSDS is not supposed to make
recommendations about implementation. For implementing I understand
that the Galois shift register is sometimes preferred over the Fibonacci
form. However, for understanding and for setting an initial seed,
Fibonacci has tremendous advantage because WYSIWYG, if you remember that
phrase from the early Apple computers, what you see is what you get.</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
You might also remember that
we had a recent go-around in the code and synch WG about how to show these
shift registers and we (GSFC) were recommending Fibonacci with particular
labeling of the cells so that the polynomial is directly related to the
cells that are tapped. Yes, I realize that this can also be done
for the Galois form. Another value of the Fibonacci with the particular
cell numbering is that it is what MatLab uses. So when people are
doing simulations, no conversion is needed. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
As you might remember there is
an ambiguity between the associated polynomial and the shift register labeling.
A particular pattern can be generated in one direction or the reverse.
We had a particular proposal and it turned out that MatLab used the
same convention. Our proposal was discarded since it would
be too much editing to get all the books to follow the same convention,
and maybe other reasons. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
But in any case, seems better
from an understanding point of view to use Fibonacci. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Victor</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"><b>From:</b>
Kazz, Greg J (US 312B) <</span><a href=mailto:greg.j.kazz@jpl.nasa.gov><span style=" font-size:11pt;color:#0082bf;font-family:Calibri"><u>greg.j.kazz@jpl.nasa.gov</u></span></a><span style=" font-size:11pt;font-family:Calibri">>
<b><br>
Sent:</b> Monday, May 17, 2021 12:31 PM<b><br>
To:</b> Andrews, Kenneth S (JPL-332B)[JPL Employee] <</span><a href=mailto:kenneth.s.andrews@jpl.nasa.gov><span style=" font-size:11pt;color:#0082bf;font-family:Calibri"><u>kenneth.s.andrews@jpl.nasa.gov</u></span></a><span style=" font-size:11pt;font-family:Calibri">><b><br>
Cc:</b> Sank, Victor J. (GSFC-567.0)[SCIENCE SYSTEMS AND APPLICATIONS INC]
<</span><a href=mailto:victor.j.sank@nasa.gov><span style=" font-size:11pt;color:#0082bf;font-family:Calibri"><u>victor.j.sank@nasa.gov</u></span></a><span style=" font-size:11pt;font-family:Calibri">>;
Kazz, Greg J (US 312B) via SLS-SLP <</span><a href="mailto:sls-slp@mailman.ccsds.org"><span style=" font-size:11pt;color:#0082bf;font-family:Calibri"><u>sls-slp@mailman.ccsds.org</u></span></a><span style=" font-size:11pt;font-family:Calibri">><b><br>
Subject:</b> Your LFSR OID frame RIDs affecting USLP, TM, AOS SDLPs</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Hi
Ken,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">The
SLP WG decided to put both of your diagrams into a new non-normative annex
in USLP, TM, and AOS.</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">The
text in the normative part of the link layer books will state:</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<div><span style=" font-size:12pt;font-family:Times New Roman">The TFDZ
of an OID Transfer Frame shall be generated by use of a 32-cell Linear
Feedback Shift Register (LFSR) with polynomial 1 + D + D<sup>2</sup> +
D<sup>22</sup> +D<sup>32</sup></span><span style=" font-size:12pt;font-family:Courier New">,
see Annex X.</span>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Where
Annex X is TBD and will be added by me to the document.</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">We
have some questions and requests for you:</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<br><span style=" font-size:10pt;font-family:sans-serif">1.
</span><span style=" font-size:10pt;font-family:Arial">Why
does the initialization data differ from one figure to the other one?</span><span style=" font-size:14pt">
</span>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:10pt;font-family:sans-serif">2.
</span><span style=" font-size:12pt;font-family:Calibri">The
‘1’ in the figures are misleading to some WG members, please replace
‘1’ with D sub zero i.e., D<sup>0</sup> in the figures.</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:10pt;font-family:sans-serif">3.
</span><span style=" font-size:12pt;font-family:Calibri">Consensus
of WG was to specify the initialization vector </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Thanks!</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Greg</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Greg
Kazz</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Principal
Engineer</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Technical
Group Supervisor,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">PSSE/EEISE/PPSE
(312B)</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Jet
Propulsion Laboratory</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">4800
Oak Grove Dr., M/S 301-490</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Pasadena,
CA 91109</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">1+(818)393
6529(voice)</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">1+(818)393
6871(fax)</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">email:
</span><a href=mailto:greg.j.kazz@jpl.nasa.gov><span style=" font-size:11pt;color:#0082bf;font-family:Calibri"><u>greg.j.kazz@jpl.nasa.gov</u></span></a><span style=" font-size:11pt;font-family:Calibri">
</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span><tt><span style=" font-size:10pt">_______________________________________________<br>
SLS-SLP mailing list<br>
SLS-SLP@mailman.ccsds.org<br>
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</span></tt></p>
<p style="margin-top:0px;margin-Bottom:0px"></p>
<p style="margin-top:0px;margin-Bottom:0px"></p></div>
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