Space engineering
Adoption Notice of CCSDS 732.0-B-4, AOS Space Data Link Protocol
Foreword
This Adoption Notice is one document of the series of ECSS Standards intended to be applied together for the management, engineering, product assurance and sustainability in space projects and applications. ECSS is a cooperative effort of the European Space Agency, national space agencies and European industry associations for the purpose of developing and maintaining common standards. Requirements in this Standard are defined in terms of what shall be accomplished, rather than in terms of how to organize and perform the necessary work. This allows existing organizational structures and methods to be applied where they are effective, and for the structures and methods to evolve as necessary without rewriting the standards.
This Adoption Notice has been prepared by the ECSS Space Communications Working Group, reviewed by the ECSS Executive Secretariat and approved by the ECSS Technical Authority.
Disclaimer
ECSS does not provide any warranty whatsoever, whether expressed, implied, or statutory, including, but not limited to, any warranty of merchantability or fitness for a particular purpose or any warranty that the contents of the item are error-free. In no respect shall ECSS incur any liability for any damages, including, but not limited to, direct, indirect, special, or consequential damages arising out of, resulting from, or in any way connected to the use of this document, whether or not based upon warranty, business agreement, tort, or otherwise; whether or not injury was sustained by persons or property or otherwise; and whether or not loss was sustained from, or arose out of, the results of, the item, or any services that may be provided by ECSS.
Published by: ESA Requirements and Standards Section ESTEC, P.O. Box 299, 2200 AG Noordwijk The Copyright: 2023© by the European Space Agency for the members of ECSS## Change log
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ECSS-E-AS-50-23C Rev.1
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First issue
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ECSS-E-AS-50-23C Rev.1
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First issue, Revision 1
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Scope
This document identifies the clauses and requirements modified with respect to the standard CCSDS 732.0-B-4, AOS Space Data Link Protocol, Issue 4, October 2021 for application in ECSS.
Context information
In the standard CCSDS 732.0-B-4 “AOS Space Data Link Protocol” CCSDS specifies a data link layer protocol for the efficient transfer of space application data of various types and characteristics over space links. The protocol specified in CCSDS 732.0-B-4 “AOS Space Data Link Protocol” has a similar purpose as CCSDS 132.0-B-3 “TM Space Data Link Protocol” and supports some features not available in the TM Space Data Link Protocol.
With this Adoption Notice ECSS is adopting and applying CCSDS 732.0-B-4 with a minimum set of modifications, identified in the present document, to allow for reference and for a consistent integration in the ECSS system of standards.
ECSS-E-ST-50-03C Space data links – Telemetry transfer frame protocol (31 July 2008) is superseded by the following two Adoption Notices: ECSS-E-AS-50-22 and ECSS-E-AS-50-23 (latest versions). The ECSS standard ECSS-E-ST-50-03 was limited to the TM Transfer Frame: it did not include the AOS Transfer Frame.
Mapping of superseded ECSS-E-50-xx Standards w.r.t. ECSS Adoption Notice versus CCSDS Standards.
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Superseded ECSS
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ECSS Adopted Notice
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Based on CCSDS
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ECSS-E-ST-50-01C
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ECSS-E-AS-50-21
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CCSDS 131.0-B-x
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ECSS-E-ST-50-03C
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ECSS-E-AS-50-22
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CCSDS 132.0-B-x
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ECSS-E-AS-50-23
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CCSDS 732.0-B-x
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ECSS-E-ST-50-04C
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ECSS-E-AS-50-24
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CCSDS 231.0-B-x
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ECSS-E-AS-50-25
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CCSDS 232.0-B-x
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ECSS-E-AS-50-26
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CCSDS 232.1-B-x
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NOTE: The applicable CCSDS Standard referred to by the ECSS Adoption Notice is stated per latest version of the ECSS Adoption Notice.
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Abbreviated terms
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Abbreviation
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Meaning
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AOS
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Advanced Orbiting Systems
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SDLS
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Space Data Link Security
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Application requirements
ECSS-E-AS-50-23_1540001CCSDS 732.0-B-4, AOS Space Data Link Protocol, Issue 4, October 2021 shall apply with the following amendments listed in Table 41.
ECSS-E-AS-50-23_1540002Table 41: Applicability table for CCSDS 732.0-B-4
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Clause or requirement number
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Applicability
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Applicable text for ECSS
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Comments
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Text as in the original CCSDS document
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4.1.2.5.2
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Modified
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The Replay Flag shall be set to ‘0’.
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CCSDS requirement modified restricted use of the Replay Flag. Sentence “Recognizing the need to store Transfer Frames during periods when the space link is unavailable, and to retrieve them for subsequent replay when the link is restored, this flag shall alert the receiver of the Transfer Frames with respect to its ‘realtime’ or ‘replay’ status. Its main purpose is to discriminate between realtime and replay Transfer Frames when they both may use the same Virtual Channel.”
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Recognizing the need to store Transfer Frames during periods when the space link is unavailable, and to retrieve them for subsequent replay when the link is restored, this flag shall alert the receiver of the Transfer Frames with respect to its ‘realtime’ or ‘replay’ status. Its main purpose is to discriminate between realtime and replay Transfer Frames when they both may use the same Virtual Channel.
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4.1.2.5.2
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New NOTE
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NOTE – When the Replay Flag is ‘0’ it indicates a Realtime Transfer Frame. CCSDS allows also the value ‘1’ for this flag to indicate Replay Transfer Frames. ECSS does not allow this as there are alternative means of replaying Frames and there is an increase of complexity for processing at Receiving End.
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New NOTE added.
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4.1.2.5.3
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Deleted requirement
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CCSDS requirement deleted.
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The Replay Flag is interpreted as follows:a) ‘0’ = Realtime Transfer Frame;b) ‘1’ = Replay Transfer Frame.
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4.1.2.5.3
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Deleted NOTES
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CCSDS NOTES deleted.
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NOTES1 Owing to the wide spectrum of onboard storage and retrieval technology options, the exact interpretation of this Flag is necessarily the subject of negotiation between projects and cross-support organizations. For instance, it may be interpreted to indicate that the value of the Virtual Channel Frame Count field on the replayed VC decreases, rather than increases, as a function of reverse playback.2 If Transfer Frames are stored after encoding by the Channel Coding Sublayer, they must be re-encoded if the status of the Replay Flag is altered after retrieval.
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4.1.2.6.1
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Modified
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NOTE 1
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CCSDS NOTES modified: existing NOTE is given a number – the content of the NOTE is unchanged
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NOTE
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4.1.2.6.1
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New NOTE
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NOTE 2 – The use of the Frame Header Error Control may be restricted to Physical Channels where the AOS Transfer Frames are not protected by an error-correcting code in the Synchronization and Channel Coding Sublayer. For example, if the frames are protected by e.g. a Reed-Solomon code, the use of the Frame Header Error Control brings no benefit and is strongly discouraged.
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New NOTE added.
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Bibliography
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ECSS-E-AS-50-21C Rev.1
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Space engineering - Adoption Notice of CCSDS 131.0-B-4, TM Synchronization and Channel Coding
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ECSS-E-AS-50-22C Rev.1
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Space engineering - Adoption Notice of CCSDS 132.0-B-3, TM Space Data Link Protocol
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ECSS-E-AS-50-23C Rev.1
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Space engineering -Adoption Notice of CCSDS 732.0-B-4, AOS Space Data Link Protocol
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ECSS-E-AS-50-24C Rev.1
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Space engineering - Adoption Notice of CCSDS 231.0-B-4, TC Synchronization and Channel Coding
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ECSS-E-AS-50-25C Rev.1
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Space engineering - Adoption Notice of CCSDS 232.0-B-4, TC Space Data Link Protocol
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ECSS-E-AS-50-26C
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Space engineering - Adoption Notice of CCSDS 232.1-B-2, Communications Operation Procedure-1
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ECSS-E-ST-50-01C
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Space engineering - Space data links - Telemetry synchronization and channel coding
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ECSS-E-ST-50-03C
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Space engineering - Space data links - Telemetry transfer frame protocol
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ECSS-E-ST-50-04C
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Space engineering - Space data links - Telecommand protocols synchronization and channel coding
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CCDSD 132.0-B-3
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TM Space Data Link Protocol – Blue Book, Issue 3, October 2021
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