Unformatted text preview: s specification. In
addition to the parameters specified in this annex, an implementation can provide other
parameters to the service user (e.g., parameters for controlling the service, monitoring
performance, facilitating diagnosis, and so on).
A2 OVERVIEW OF THE SERVICE The TM Synchronization and Channel Coding provides unidirectional (one way) transfer of a
sequence of fixed-length TM or AOS Transfer Frames at a constant frame rate over a
Physical Channel across a space link, with optional error detection/correction.
Only one user can use this service on a Physical Channel, and Transfer Frames from different
users are not multiplexed together within one Physical Channel.
A3.1 SERVICE PARAMETERS
FRAME A3.1.1 The Frame parameter is the service data unit of this service and shall be either a TM
Transfer Frame defined in reference  or an AOS Transfer Frame defined in reference .
A3.1.2 The length of any Transfer Frame transferred on a Physical Channel must be the
same, and is established by management. CCSDS 131.0-B-2 Page A-1 August 2011 CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODING A3.2 QUALITY INDICATOR The Quality Indicator parameter shall be used to notify the user at the receiving end of the
service that there is an uncorrectable error in the received Transfer Frame.
A3.3 SEQUENCE INDICATOR The Sequence Indicator parameter shall be used to notify the user at the receiving end of the
service that one or more Transfer Frames of the Physical Channel have been lost as the result
of a loss of frame synchronization.
A4 SERVICE PRIMITIVES A4.1
A4.1.1 GENERAL The service primitives associated with this service are: a) ChannelAccess.request;
A4.1.2 The ChannelAccess.request primitive shall be passed from the service user at the
sending end to the service provider to request that a Frame be transferred through the
Physical Channel to the user at the receiving end.
A4.1.3 The ChannelAccess.indication shall be passed from the service provide...
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- Spring '14
- ........., Error detection and correction, CCSDS