[SLS-CC] [EXTERNAL] Re: VCM technical corrigendum wording (AI_21_01)
Shames, Peter M (US 312B)
peter.m.shames at jpl.nasa.gov
Thu Aug 19 19:08:15 UTC 2021
Dear Andrea,
I do understand that the WG wishes to publish this document with an inaccurate “informative” diagram. I want to go on record that I believe firmly that this is a mistake. I also think that your statement could just as easily have read:
Concerning the technical conclusions: VCM blue book defines the modulations (PSK/APSK), filtering/shaping (SRRC). There is nothing that defines the transparent transmission of the bits as defined by ISO 7498 except for CCSDS 401 document. The remaining portions (frequency, phase noise tolerance, I/Q imbalance) in BlueBook 401 define the lowest sub- layer.
This could have been the conclusion of the WG, and we reached consensus as required by the CCSDS organization and processes YB.
Finally, I wish to remark that we're dealing just with notional, but inaccurate, informative diagram. The BB clearly will include that 401 shall be taken into account, hence, from pragmatic point of view the WG is choosing to publish an document with an known inaccurate diagram.
This is, in my technical opinion, an accurate statement of what you have chosen to do. From my pragmatic point of view I do not wish to spend any more of my time trying to convince you to do the right thing. So if you do not want to fix it, in accordance with CCSDS consensus process, I will stand aside and let you do the inaccurate thing.
Regards, Peter
________________________________________________________
Peter Shames
CCSDS Systems Engineering Area Director
Jet Propulsion Laboratory, MS 301-490
California Institute of Technology
Pasadena, CA 91109 USA
Telephone: +1 818 354-5740, Fax: +1 818 393-6871
Internet: Peter.M.Shames at jpl.nasa.gov
________________________________________________________
We must recognize the strong and undeniable influence that our language exerts on our ways of thinking and, in fact, delimits the abstract space in which we can formulate - give form to - our thoughts.
Niklaus Wirth
From: SLS-CC <sls-cc-bounces at mailman.ccsds.org> on behalf of "Andrea Modenini (external)" <Andrea.Modenini at esa.int>
Date: Thursday, August 19, 2021 at 6:49 AM
To: Space Link Coding & Synchronization Working Group <sls-cc at mailman.ccsds.org>
Cc: "Ignacio.Aguilar.Sanchez at esa.int" <Ignacio.Aguilar.Sanchez at esa.int>
Subject: Re: [SLS-CC] [EXTERNAL] Re: VCM technical corrigendum wording (AI_21_01)
Dear Colleagues,
regarding the VCM technical corrigendum, I did not get additional comments.
In view of the WG consensus, I kindly ask SLS AD to raise a resolution for publication (copy in attachment)
Kind Regards
HE Space Operations for ESA - European Space Agency
Ph.D. Andrea Modenini
Communication Systems & Technologies Engineer
TT&C and PDT Systems & Techniques Section (TEC-EST)
RF Systems Division
ESTEC
Keplerlaan 1, PO Box 299
NL-2200 AG Noordwijk, The Netherlands
andrea.modenini at esa.int | www.esa.int<https://urldefense.us/v3/__http:/www.esa.int/__;!!PvBDto6Hs4WbVuu7!dlWTyv111tTsX17d85u5I5r6V_MZo9fqQxMO5GtJ3x6wC0UwPLcyddXcIs3IOS46VCtc8WVO$>
T +31 71 56 53439, M +31 6 484 56 527
From: Andrea Modenini/estec/ESA
To: "Shames, Peter M (US 312B)" <peter.m.shames at jpl.nasa.gov>
Cc: "Lee, Dennis K (US 332G)" <dennis.k.lee at jpl.nasa.gov>, "Enrico Vassallo/esoc/ESA" <Enrico.Vassallo at esa.int>, "EXTERNAL-Pietras, John V (US 332C-Affiliate)" <john.pietras at gst.com>, "Hamkins, Jon (US 3300)" <jon.hamkins at jpl.nasa.gov>, "Andrews, Kenneth S (US 332B)" <kenneth.s.andrews at jpl.nasa.gov>, "Space Link Coding & Synchronization Working Group" <sls-cc at mailman.ccsds.org>, Ignacio Aguilar Sanchez/estec/ESA at ESA, "Gilles Moury" <Gilles.Moury at cnes.fr>
Date: 28-07-21 16:42
Subject: Re: [EXTERNAL] Re: [SLS-CC] VCM technical corrigendum wording (AI_21_01)
________________________________
Dear Peter,
thanks for your feedback. Sorry again for taking some time in replying, but I am still working 20% of the time.
Concerning the involvement of the RFM working group in the VCM technical corrigendum, we had the joint RFM/C&S for which edits were agreed, representative was always involved, and we never got negative feedback.
Additionally, this will be also crosschecked at SLS AD level before going to SLS resolution.
Concerning the technical conclusions: VCM blue book defines the modulations (PSK/APSK), filtering/shaping (SRRC). There is nothing that prevents to define the transparent transmission of the bits as defined by ISO 7498. The remaining portions (frequency, phase noise tolerance, I/Q imbalance) in BlueBook 401 appear rather small for being an actual layer.
This was the conclusion of the WG, and we reached consensus as required by the CCSDS organization and processes YB.
Finally, I wish to remark that we're dealing just with notional informative diagram. The BB clearly will include that 401 shall be taken into account, hence, from pragmatic point of view, I don't see any mistake in the WG assessment.
Kind Regards
HE Space Operations for ESA - European Space Agency
Ph.D. Andrea Modenini
Communication Systems & Technologies Engineer
TT&C and PDT Systems & Techniques Section (TEC-EST)
RF Systems Division
ESTEC
Keplerlaan 1, PO Box 299
NL-2200 AG Noordwijk, The Netherlands
andrea.modenini at esa.int | www.esa.int<https://urldefense.us/v3/__http:/www.esa.int/__;!!PvBDto6Hs4WbVuu7!dlWTyv111tTsX17d85u5I5r6V_MZo9fqQxMO5GtJ3x6wC0UwPLcyddXcIs3IOS46VCtc8WVO$>
T +31 71 56 53439, M +31 6 484 56 527
From: "Shames, Peter M (US 312B)" <peter.m.shames at jpl.nasa.gov>
To: "Andrea Modenini (external)" <Andrea.Modenini at esa.int>
Cc: "Space Link Coding & Synchronization Working Group" <sls-cc at mailman.ccsds.org>, "Enrico Vassallo/esoc/ESA" <Enrico.Vassallo at esa.int>, "Lee, Dennis K (US 332G)" <dennis.k.lee at jpl.nasa.gov>, "Andrews, Kenneth S (US 332B)" <kenneth.s.andrews at jpl.nasa.gov>, "Hamkins, Jon (US 3300)" <jon.hamkins at jpl.nasa.gov>, "EXTERNAL-Pietras, John V (US 332C-Affiliate)" <john.pietras at gst.com>
Date: 26-07-21 23:14
Subject: Re: [EXTERNAL] Re: [SLS-CC] VCM technical corrigendum wording (AI_21_01)
________________________________
Hi Andrea,
Thanks for this feedback. I have heard about this topic from both Ken Andrews and John Pietras. I must say, in all honesty, that I am both not surprised and also disappointed by the choice that the SLS CC WG has made. I also wonder if the RFM WG would agree with your characterization that the “RFM Blue Book 401 rather provides a set of requirements to be fulfilled when transmitting at Radio Frequency, but not a function.”
In fact, that “pseudo protocol stack” diagram from 431, and also 131.0, .1, .2 makes direct reference to “Relationship to OSI Layers”. This is not “functions”, per se, but “OSI layers”. The text above this figure, in 431.0-B, says:
“The synchronization and channel coding sublayer provides methods of synchronization and channel coding for transferring Transfer Frames over a space link while the Physical Layer provides the RF and modulation methods for transferring a stream of bits over a space link in a single direction.
This Recommended Standard covers functions in both the Synchronization and Channel Coding Sublayer and the Physical Layer. “
I think that we would all have to agree that the “functions” in the OSI Layer 1 relative to RF transmission include all of the physical layer aspects required to apply modulation, and to do filtering, signal shaping, and actual radiation of the RF signal. For VCM we can add “physical layer signaling” to that set of functions. All of these, as far as I can tell, are “functions” of Layer 1.
I could quote all of the relevant section of the BRM, ISO 7498, but I suspect you are familiar with them. I will quote the most relevant parts:
7.7.3.3. Physical Connections
7.7.3.3.1 The Physical Layer provides for the transparent transmission of bit streams between data-link-entities across physical-connections.
7.7.3.3.2 A data-circuit is a communication path in the physical media for OSI among two or more physical-entities, together with the facilities necessary in the Physical Layer for the transmission of bits on it.
I think we all know that the BRM does not expressly cover RF communications, nor does it cover optical comms. That said, it does use sufficiently broad language that it is, in my opinion, still an extremely useful reference. In this case “facilities necessary in the Physical Layer for the transmission of bits” equates, in my mind, exactly to “modulation, filtering, signal shaping, and actual radiation of the RF signal”. Whether the term of art is “facilities” or “functions” is a terminology distinction that does not feel like it is worth arguing about. The BRM uses both “function” and “facility” and seems to mean more or less the same thing in both instances.
The last point I will make about this figure 2-1 is that it clearly states that the “VCM Protocol” covers all of the “Physical Layer”, which seems to mean all of OSI Layer 1. I do believe that the VCM includes some physical layer functions, like a selection of modulations and pilot signals, but not all of them, so I continue to believe that this figure, on the surface of it, is both mis-leading and inaccurate. I also believe that in the absence of the functions, features, and facilities defined in the CCSDS 401.0-B that you would be lacking the required definitions for several key functions and / or facilities for RF signal radiation, and constraints thereon, that are only documented in CCSDS 401.0-B.
My conclusion, therefore, is that if the CCSDS stack does not include, explicitly, CCSDS 401.0-B, there is no complete guidance for RF radiation, and therefore Layer 1 is incomplete.
I really wish that you guys would just fix these figures so that this ambiguity is removed. The corresponding figure and text in TM Synch and channel coding, CCSDS 131.0-B, contains no such ambiguity.
Thanks, Peter
From: "Andrea Modenini (external)" <Andrea.Modenini at esa.int>
Date: Monday, July 26, 2021 at 12:58 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov>
Cc: Space Link Coding & Synchronization Working Group <sls-cc at mailman.ccsds.org>
Subject: Re: [EXTERNAL] Re: [SLS-CC] VCM technical corrigendum wording (AI_21_01)
Dear Peter,
sorry for the late reply, I have been hold by other activities, and I am also in a personal leave.
Regarding the stack, in our opinion the VCM Blue Book defines also the physical layer function, since it fully specifies the modulations and constellations to be implemented.
In this respect, the RFM Blue Book 401 rather provides a set of requirements to be fulfilled when transmitting at Radio Frequency, but not a function.
Hence, our preference as WG is to insert the sentences as indicated in my previous email, but to not modify the stack.
Please let us know your opinion, so that we could possible proceed with the WG resolution.
Regards
HE Space Operations for ESA - European Space Agency
Ph.D. Andrea Modenini
Communication Systems & Technologies Engineer
TT&C and PDT Systems & Techniques Section (TEC-EST)
RF Systems Division
ESTEC
Keplerlaan 1, PO Box 299
NL-2200 AG Noordwijk, The Netherlands
andrea.modenini at esa.int | www.esa.int<https://urldefense.us/v3/__http:/www.esa.int/__;!!PvBDto6Hs4WbVuu7!d5Sq5RR5u3CiQHi0pPU9SNMfwjuy8mRQK2_zDmvs_G35TZ11GNTO6MRtZEi46MbTmcjuyrPF$>
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From: "Shames, Peter M (US 312B)" <peter.m.shames at jpl.nasa.gov>
To: "Andrea Modenini (external)" <Andrea.Modenini at esa.int>, "Space Link Coding & Synchronization Working Group" <sls-cc at mailman.ccsds.org>
Date: 07-07-21 21:05
Subject: Re: [EXTERNAL] Re: [SLS-CC] VCM technical corrigendum wording (AI_21_01)
________________________________
Dear Andrea & S&CC WG members,
I fully support the idea of aligning all three of the “VCM suite” coding and synch standards. As we have tried to make clear in the updates we are making to the SCCS-ARD, our analysis shows that all three of these approaches are very nearly identical technically, with only what appear to be modest differences in how they are designed. I do not wish to get into the whole discussion of how we arrived at this situation, only to point out that this is where we are, and that this is how we view the technical details.
In the attached slides I have included, as pgs 2 & 3, the way that we are approaching the description of what we are calling the “VCM Suite” and how we plan to document these relative to the rest of the S&CC specs as well as how they relate to the several link layer protocols. We reviewed these diagrams during the “SCCS Coordination” meeting that involved SLS, SIS, CSS, and SEA WG and Area leads. And we just discussed these during the follow up SAWG meeting that Gilles was present at. We agreed to ask your WG for feedback, so I am taking this opportunity to do this.
I have also included, on pg 1, a proposed markup of your text and Fig 2-1 from the 431.1 document. We think it will be clearer if this figure, and the associated text, for the 431.1 (and the others in the VCM Suite) all use the identical figure, and that this figure, and the related text, clearly states that these standards only address the upper part (modulation sub-layer) of the Physical Layer and not the lower sub-layer where the 401.0 document addresses the RF frequency bands, bandwidth limitations, etc.
Please review this feedback and see if you can agree to it. Also, it would be very useful to us if your WG would review the VCM Suite diagrams I have sent and make sure that they are technically correct.
Very best regards, Peter
From: SLS-CC <sls-cc-bounces at mailman.ccsds.org> on behalf of "Andrea Modenini (external)" <Andrea.Modenini at esa.int>
Date: Wednesday, July 7, 2021 at 9:30 AM
To: Space Link Coding & Synchronization Working Group <sls-cc at mailman.ccsds.org>
Subject: [EXTERNAL] Re: [SLS-CC] VCM technical corrigendum wording (AI_21_01)
Dear all,
I did not receive any comment about the VCM BB from the WG.
However, considering the outcome of the DVB-S2 BB review we had today, I have myself a comment.
We aligned the SCCC and DVB-S2 BBs for having a sentence that states the need to consider CCSDS 401 BB.
On the same line, I would propose to modify Section 2 as provided below (italic part highlights the addition).
You can find in attachment also the word file in tracking-changes mode for your convenience.
Please let me know if there is any objection, or additional point to consider, no later than 12th July EOB.
I will afterward request an Area Resolution for having the technical corrigendum.
Kind Regards,
Andrea
-------------
This Recommended Standard covers functions in both the Synchronization and Channel Coding Sublayer and the Physical Layer, the latter for what concerns the modulation schemes. CCSDS 401.0-B [5] covers additional features of the Physical Layer like frequency bands, polarizations, etc. that are not described or referenced here.
HE Space Operations for ESA - European Space Agency
Ph.D. Andrea Modenini
Communication Systems & Technologies Engineer
TT&C and PDT Systems & Techniques Section (TEC-EST)
RF Systems Division
ESTEC
Keplerlaan 1, PO Box 299
NL-2200 AG Noordwijk, The Netherlands
andrea.modenini at esa.int | www.esa.int<https://urldefense.us/v3/__http:/www.esa.int/__;!!PvBDto6Hs4WbVuu7!ZprtUS7KJ1pZpltt-3sln6BkmB--RAe2fXWcA3tewDmnD-hvb2k5FJtUbftvY77dWfg0GNDT$>
T +31 71 56 53439
From: Andrea Modenini/estec/ESA
To: "Space Link Coding & Synchronization Working Group" <sls-cc at mailman.ccsds.org>
Date: 10-06-21 17:28
Subject: [SLS-CC] VCM technical corrigendum wording (AI_21_01)
________________________________
Dear colleagues,
please find enclosed the proposed changes by Jon to the VCM BB discussed during the joint C&S/RFM meeting. Please send your comments before 1st July 2021 (if any) directly to John with CC Enrico and I, and C&S mailing list.
Regards
Andrea
HE Space Operations for ESA - European Space Agency
Ph.D. Andrea Modenini
Communication Systems & Technologies Engineer
TT&C and PDT Systems & Techniques Section (TEC-EST)
RF Systems Division
ESTEC
Keplerlaan 1, PO Box 299
NL-2200 AG Noordwijk, The Netherlands
andrea.modenini at esa.int | www.esa.int<https://urldefense.us/v3/__http:/www.esa.int/__;!!PvBDto6Hs4WbVuu7!ZprtUS7KJ1pZpltt-3sln6BkmB--RAe2fXWcA3tewDmnD-hvb2k5FJtUbftvY77dWfg0GNDT$>
T +31 71 56 53439
----- Forwarded by Andrea Modenini/estec/ESA on 10-06-21 17:25 -----
From: "Jon Hamkins" <Jon.Hamkins at jpl.caltech.edu>
To: "Andrea Modenini (external)" <Andrea.Modenini at esa.int>, "Enrico.Vassallo at esa.int" <Enrico.Vassallo at esa.int>
Date: 09-06-21 18:48
Subject: VCM technical corrigendum wording (AI_21_01)
________________________________
Andrea, Enrico,
Attached is a draft VCM technical corrigendum in response to AI_21_01 from the C&S WG. I completed this in consultation with Ken Andrews and John Pietras.
The main changes are in two places: Section 3.2.3 and Section 3.3.2.3 to 3.3.2.4. In summary, with the new wording the randomization is determined by VCM type:
* Type 1 (SCCC-like) VCM will randomize the Transfer Frames as the SCCC standard does, using the TM randomizer.
* Type 2 (DVB-S2-like) VCM will randomize the sliced encoder-inputs as the DVB-S2 standard does, using the ETSI DVB-S2 baseband scrambler.
This will make the CCSDS VCM standard consistent with the 131.2-B-1 and 131.3-B-1 books (SCCC and DVB-S2), with respect to randomization.
These changes are not related to randomization that occurs after encoding. The VCM protocol standard already applies post-encoding randomization, at the physical layer.
Can you forward this message to the RFM and C&S mailing lists along with your guidance on how/when to respond with comments? I believe we agreed to resolve this action by email.
----Jon
--
Jon Hamkins
Chief Technologist, Communications, Tracking, and Radar Division
O 818-354-4764 (preferred) | M 626-658-6220 (does not work at home)
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