Document number
205065
Version
Rev. N
Issue date
2019-02-04
Sirius OBC and TCM User Manual
Page
117
of
174
Table 7-16: Fallback TC Handler APID
Parameter
Value
Description
TC Handler APID
0xAF
Fallback APID configuration of APID of TC Handler in TCM
Core Application
7.5. Telemetry
Telemetry is simultaneously sent on all the transceiver interfaces, i.e. the RS422 (TRX1),
the LVDS (TRX2) and umbilical (UMBI) interfaces. VC 0 and VC 1 are supported for TM
Data and VC 7 is reserved for idle-frames. The CCSDS IP generates complete TM Transfer
Frames from PUS packets. If a PUS packet does not fit in one TM Transfer Frame, the
CCSDS module splits the packet into several TM Transfer Frames. If a PUS packet not does
fill the whole TM Transfer Frame, an idle-packet is added as padding to fill the frame. The
following telemetry settings are configurable by RMAP-commands (see 7.12):
•
Divisor of TM Clock
•
Inclusion of CLCW of TM Transfer Frames
•
Inclusion of Frame Error Control Field of TM Transfer Frames
•
Updating of Master Channel Frame Counter
•
Idle frame generation (sent on VC7 when no data is sent on VC0 or VC1)
•
Convolutional encoding
•
Pseudo randomization
The TCM-S supports the format of TM Transfer Frames described in [RD8].
7.6. Telecommands
Telecommands can be received on the RS422 (TRX1), the LVDS (TRX2) or the umbilical
(UMBI) interface.
The TCM actively searches for Command Link Transmission Units (CLTU), i.e.
telecommands, on all three inputs simultaneously (as long as they are enabled). When a
telecommand start sequence is detected, the other inputs are ignored during telecommand
reception. The search will restart once the entire telecommand is either received or a
reception error is detected. In short, the telecommand reception uses the following reception
logic, also illustrated in
•
All incoming signals on the inputs are synchronized to the system clock domain.
•
The BCH decoder is configured in error-correcting mode
•
When the CLTU receptor has detected and decoded a start pattern, it sets an enable
signal for the active path, indicating that this CLTU receptor is now active. If one or
more bit-errors occur in the start pattern, the CLTU will be rejected, which is not
compliant to handling of one-bit errors described in [RD14] since one-bit errors shall be
corrected when BCH decoder is configured in error-correcting mode.
•
The telecommand path activated is set until the reception status changes, i.e. the
current telecommand is finished and a new start pattern is detected correctly on a
different CLTU path.
•
The selected telecommand clock, data and enable signals are now forwarded through
the mux to the BCH decoder, rejecting data and clock on inactive data paths.
