This technique reduces the probability of

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Unformatted text preview: ly eliminate the possibility of retransmission, but the probability of retransmission can be made very small by using this technique. At the receiving end, COP-1 can deliver the SDUs (user data) contained in the received sequence of Transfer Frames to the receiving user in sequence and without duplication using the standard procedure of COP-1, even though the sequence of Transfer Frames has been transmitted multiple times. 5.5 CAN COP-1 BE APPLIED TO BLIND COMMANDING? Yes. It is sometimes necessary to transmit commands when telemetry is not available. In such cases, the Expedited Service of COP-1 (see 4.4.2.3) should be used because the Sequence-Controlled Service requires a feedback loop via the telemetry link for proper operations. If the Expedited Service is used, however, there is no guarantee that all transmitted data is delivered to the receiving user. Since transmitted Transfer Frames are always protected by the error correction/detection capability of the Synchronization and Channel Coding Sublayer, data delivered to the receiving user has a very high probability that it is error-free, but there may be gaps in the data because Transfer Frames containing errors not correctable by the Synchronization and Channel Coding Sublayer are discarded and not retransmitted. CCSDS 130.2-G-1 Page 5-2 December 2007 CCSDS REPORT CONCERNING THE SPACE DATA LINK PROTOCOLS ANNEX A ACRONYMS This annex lists the acronyms and abbreviations used in this Report. AOS Advanced Orbiting Systems ARQ Automatic Repeat Request CCSDS Consultative Committee for Space Data Systems CLCW Communications Link Control Word FARM Frame Acceptance and Reporting Mechanism FOP Frame Operation Procedure GVCID Global Virtual Channel Identifier HDLC High-Level Data Link Control ID Identifier IP Internet Protocol MAP ID Multiplexer Access Point Identifier MAP Multiplexer Access Point MAPA Multiplexer Access Point Access MAPP Multiplexer Access Point Packet MC Master Channel MC_FSH Master Channel Frame Secondary Header MC_OCF Master Channel Operational Control Field MCID Master Channel Identifier MCF Master Channel Frame PVN Packet Version Number QoS Quality of Service SAP Service Access Point CCSDS 130.2-G-1 Page A-1 December 2007 CCSDS REPORT CONCERNING THE SPACE DATA LINK PROTOCOLS SCI Service Control Information SCID Spacecraft Identifier SDLP Space Data Link Protocol SDU Service Data Unit SLE Space Link Extension TC Telecommand TFVN Transfer Frame Version Number TM Telemetry VC Virtual Channel VC_FSH Virtual Channel Frame Secondary Header VC_OCF Virtual Channel Operational Control Field VCA Virtual Channel Access VCID Virtual Channel Identifier VCF Virtual Channel Frame VCP Virtual Channel Packet CCSDS 130.2-G-1 Page A-2 December 2007 CCSDS REPORT CONCERNING THE SPACE DATA LINK PROTOCOLS ANNEX B SUMMARY OF SERVICES This annex shows, in a schematic way, the services provided by each of the Space Data Link Protocols and how these services can be multiplexed onto a space link. The diagrams in th...
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