ISO 22642:2015 pdf download

ISO 22642:2015 pdf download.Space data and information transfer systems — TC synchronization and channel coding
1.3 APPLICABILITY
This Recommended Standard applies to the creation of Agency standards and to the future data communications over space links between CCSDS Agencies in cross-support situations. This Recommended Standard includes comprehensive specification of the data formats and procedures for inter-Agency cross support. It is neither a specification of, nor a design for, real systems that may be implemented for existing or future missions. The Recommended Standard specified in this document is to be invoked through the normal standards programs of each CCSDS Agency, and is applicable to those missions for which cross support, based on capabilities described in this Recommended Standard, is anticipated. Where mandatory capabilities are clearly indicated in sections of this Recommended Standard, they must be implemented when this document is used as a basis for cross support. Where options are allowed or implied, implementation of these options is subject to specific bilateral cross support agreements between the Agencies involved.
2 OVERVIEW
2.1 ARCHITECTURE
Figure 2-1 illustrates the relationship of this Recommended Standard to the Open Systems Interconnection (OSI) reference model (reference [2]). Two sublayers of the Data Link Layer are defined for CCSDS space link protocols. The TC Space Data Link Protocols specified in reference [1] corresponds to the Data Link Protocol Sublayer, and provides functions for transferring data using the protocol data unit called the Transfer Frame. The Synchronization and Channel Coding Sublayer provides additional functions necessary for transferring Transfer Frames over a space link. These functions are error-control coding/decoding, delimiting/synchronizing codeblocks, and bit transition generation/removal.
2.2.2 ERROR-CONTROL CODING
This Recommended Standard specifies an error-control coding method using a modified BCH code. This is described in section 3. The modified BCH code specified in this Recommended Standard may be decoded either in an error-detecting mode or in an error-correcting mode, depending on mission requirements. If the modified BCH code is decoded in an error-detecting mode, the Frame Error Control Field (FECF) defined in reference [1] may be used to reduce the probability of undetected errors. NOTE – In this Recommended Standard, the characteristics of the codes are specified only to the extent necessary to ensure interoperability and cross-support. The specification does not attempt to quantify the relative coding gain or the merits of each approach discussed, nor the design requirements for encoders or decoders.