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Unformatted text preview: mes) and “Look for Directive” (for type-BC frames). It will need a count variable, which
will need to be set or reset in other FOP-1 actions. For example, the count needs to be reset in the
action “Remove Acknowledged Frames from Sent_Queue”. TCretrans7 2008Sep09 I.B. + M.A. DE LANDE LONG
SOFTWARE + CONSULTANCY
Options for repeated retransmissions for telecommand Page 8 3.2.3 New FOP-1 parameter(s)
If the systematic retransmission is implemented inside FOP-1, using the method described in section
3.2.1 or 3.2.2, then there will be a number of new FOP-1 variables, and at least one of the new
variables will need to be a parameter that can be set by the FOP-1 users and/or management.
Therefore, there will need to be a new FOP-1 directive for setting the parameter.
DIRECTIVE.request primitive has one parameter (Directive qualifier) to carry the new value. The new
directive will result in a new event in the FOP-1 State Table.
If multiple new variables are parameters, then there would need to be multiple new directives. It would
be possible to use Directive qualifier to set the values of two parameters (e.g. top 4 bits and bottom 4
bits of an 8-bit value) but this is no simpler than adding two directives. TCretrans7 2008Sep09 I.B. + M.A. DE LANDE LONG
SOFTWARE + CONSULTANCY
Options for repeated retransmissions for telecommand Page 9 3.3 Option 3: After FOP-1
A systematic retransmission could be implemented after FOP-1, in the Transfer Sublayer or in the
Synchronization and Channel Coding Sublayer.
For example, Annex C of Recommended Standard CCSDS 231.0-B-1, TC Synchronization and
Channel Coding, defines the service interface for the services provided by the Synchronization and
Channel Coding Sublayer to the user in the next layer above. The interface includes the
ChannelAccess.request primitive: ChannelAccess.request (Frames)
The definition of the primitive could be modified to include an optional repetition parameter: ChannelAccess.request (Frames, Repetitions)
Depending on the value of the Repetitions parameter, the Synchronization and Channel Coding
Sublayer would generate and transmit...
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This document was uploaded on 03/06/2014.
- Spring '14