Document number
205065
Version
Rev. N
Issue date
2019-02-04
Sirius OBC and TCM User Manual
Page
158
of
174
10. TM/TC-structure and COP-1
10.1. SCID
For commanding the spacecraft, a 10-bit Spacecraft Identifier is needed. For every mission,
a mission specific SCID is configured in the TCM-S.
10.2. APID
The application running on the TCM-S has a unique identifier, Application Process Identifier,
that is configurable for every mission by a parameter stored in the NVRAM on the TCM-S.
10.3. Virtual Channel Allocation
10.3.1. Uplink
For the uplink, VC0 is used for telecommands to be handled by SW on TCM-S. CPDUS
shall be sent on VC2.
10.3.2. Downlink
VC0 and VC1 are used for sending Telemetry from spacecraft to ground. Idle Frames are
sent on VC7.
10.4. Uplink Channel Coding, Randomization and Synchronization
10.4.1. Channel Coding
The Telecommand Code Block is BCH(63, 56) and supports Single Error Correction mode.
BCH Decoding can be enabled/disable by a configuration in NVRAM or by a RMAP
command.
10.4.2. Randomization
Derandomization of telecommands can be enabled/disabled by a configuration in NVRAM or
by a RMAP command.
10.4.3. Channel Synchronization
The 2-byte start sequence of Telecommands is 0xEB90. The 8-byte tail sequence of
Telecommands is 0xC5C5C5C5C5C5C579.
10.5. Downlink Channel Coding, Randomization and
Synchronization
10.5.1. Channel Coding
Reed-Solomon encoding by a RS (255, 223) encoder with an interleaving depth of 5,
resulting in a Telemetry Transfer Frame length of 1115 octets. RS encoding can be
enabled/disabled by a configuration in NVRAM or by a RMAP command.