<span style=" font-size:10pt;font-family:sans-serif">Dear all,</span>
<br><span style=" font-size:10pt;font-family:sans-serif"> JPL and
GSFC brought to my attention that CCSDS 732, Section 4.1.2.6, specifies
a shortened RS code that was originally meant for uncoded or convolutional
only coded telemetry links.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">However (see Victor's
email below) it was found that this specification was often misused, just
becoming an additional overhead for the link. Additionally, the specification
itself appears incomplete, leaving ambiguities to its actual implementation.</span>
<br><span style=" font-size:10pt;font-family:sans-serif">For this reason,
JPL and GSFC are proposing to eliminate it.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Could you please
pool your Agencies, and let me know your position <u>no later than 1st
October 2021</u>? </span>
<br><span style=" font-size:10pt;font-family:sans-serif">So that C&S
WG can then formalise its position to SLP before next Fall Meeting.</span>
<br><span style=" font-size:10pt;font-family:sans-serif"> </span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Kind Regards</span>
<br>
<br>
<br><span style=" font-size:8pt;color:#808080;font-family:Verdana"><b>ESA
- European Space Agency</b></span>
<br><span style=" font-size:8pt;color:#00a1e0;font-family:Verdana"><b>Ph.D.
Andrea Modenini</b></span><span style=" font-size:8pt;color:#808080;font-family:Verdana"><b><br>
TT&C Communications Systems Engineer</b></span><span style=" font-size:12pt;font-family:Tms Rmn"><b>
</b></span><span style=" font-size:8pt;color:#808080;font-family:Verdana"><br>
TT&C and PDT Systems & Techniques Section (TEC-EST)<br>
RF Systems Division<b><br>
ESTEC</b><br>
Keplerlaan 1, PO Box 299<br>
NL-2200 AG Noordwijk, The Netherlands</span><span style=" font-size:8pt;color:blue;font-family:Verdana"><u><br>
</u></span><span style=" font-size:8pt;color:#808080;font-family:Verdana">andrea.modenini@esa.int
| </span><a href=http://www.esa.int/><span style=" font-size:8pt;color:#8f8f8f;font-family:Verdana"><u>www.esa.int</u></span></a><span style=" font-size:8pt;color:#808080;font-family:Verdana"><br>
T +31 71 56 53439, M +31 6 484 56 527</span>
<br><span style=" font-size:9pt;color:#800080;font-family:sans-serif">-----
Forwarded by Andrea Modenini/estec/ESA on 17-09-21 10:35 -----</span>
<br>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">From:
</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></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">To:
</span><span style=" font-size:9pt;font-family:sans-serif">"Andrea.Modenini@esa.int"
<Andrea.Modenini@esa.int></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Cc:
</span><span style=" font-size:9pt;font-family:sans-serif">"Rodriguez,
Shannon (GSFC-5670)" <shannon.rodriguez-1@nasa.gov>, "Kazz,
Greg J (JPL-312B)[JPL Employee]" <greg.j.kazz@jpl.nasa.gov>,
"Fong, Wai H. (GSFC-5670)" <wai.h.fong@nasa.gov>, "Andrews,
Kenneth S (JPL-332B)[JPL Employee]" <kenneth.s.andrews@jpl.nasa.gov>,
"Hamkins, Jon (JPL-3300)[JPL Employee]" <jon.hamkins@jpl.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">15-09-21
21:09</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Subject:
</span><span style=" font-size:9pt;font-family:sans-serif">CCSDS
732 section 4.1.2.6 Header Error Control</span>
<br>
<hr noshade>
<br>
<br>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Andrea,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
There is a shortened 15,11 RS
code (q = 1 so shortened to 14,10) in the CCSDS 732.0-B-3 book section
4.1.2.6 that is specified for use in the transfer frame header that we
believe is a hang over from the days before the popular use of RS or other
more powerful block codes that get applied to the entire transfer frame.
It is intended for the case of convolution only code or the case
of no error correction code. We have had a few missions miss use
this code and were wondering if CCSDS should remove it from the 732 book.
You can see from the email from Greg below that JPL has no missions
that use this code and over the last approximately 20 years, GSFC is only
aware of it being used where it was not intended. It is also odd
that this code is only specified in the 732 book and not the 131 books.
</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
Being a shortened code, I find
the specification incomplete. As a shortened code it is necessary
to specify where the virtual fill should go, at the beginning or at the
end (or else ware). In addition, it is not specified what value the
virtual fill nibble (4 bits) should be. Most common would be all
zeros, but it needs to be specified. Without these additional details,
a ground station receiver vendor would have to make these parameters user
selectable. The protection leaves out the VCID count, it only covers
the MCID, VCID and Signaling Field. Seems to me an error in the VCID
counter can make the frame useless. Using this header code makes
the primary header 8 bytes long which I do not think is specified any where
else. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
Your thoughts please and if you
agree, can you ask each C&S WG member to poll their respective agency
so at the next meeting we can discuss the possibility of eliminating it
from the 732.0 blue book? </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>
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> Tuesday, September 14, 2021 11:41 AM<b><br>
To:</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">><b><br>
Subject:</b> Re: [EXTERNAL] Re: Minor wording in CCSDS 732 section 4.1.2.6
Header Error Control</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">At
least at JPL, no mission uses the AOS transfer frame header error control.
It would be worthwhile if you ask Andrea that each C&S WG member poll
their respective agency to see if at the next meeting we could see if it
could be eliminated from the 732.0 blue book. </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">Greg</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
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