GR712RC-UM, Jun 2017, Version 2.9 185 www.cobham.com/gaisler
GR712RC
26.1.2 Functions and options
The Telecommand Decoder (GRTC) only implements the Coding Layer of the telecommand protocol
standard [ECSS-E-ST-50-04C]. Other layers are to be implemented in software, e.g. Authentication
Unit (AU). The Command Pulse Distribution Unit (CPDU) is not implemented.
The following functions of the GRTC are programmable by means of registers:
• Pseudo-De-Randomisation
• Non-Return-to-Zero – Mark decoding
The following functions of the GRTC are fixed:
• Polarity of RF Available and Bit Lock inputs is active high
• Edge selection for input channel clock is rising edge
26.2 Data formats
26.2.1 Reference documents
[PSS-04-107] Packet Telecommand Standard, Issue 2
[PSS-04-151] Telecommand Decoder Standard, Issue 1
[CCSDS 231.0-B-2] TC Synchronization and Channel Coding
[CCSDS 232.0-B-2] TC Space Data Link Protocol
[CCSDS 232.1-B-2] Communications Operation Procedure-1
[ECSS-E-ST-50-04C] Space engineering - Space data links - Telecommand protocols, synchroniza-
tion and channel coding
Figure 77. Detailed block diagram showing the internal structure
GRTC
Start sequence search
TCI2DMA
NRZ-M
BCH Decoder
Coding Sub-Layer
Telecommand input
Pseudo-Derandomizer
AMBA AHB
Physical Layer
RxPtr
RxFifo RxCLDMA2AHB
TCI (AHB2TCI) Data Link Protocol Sub-Layer
TCC