Safran CORTEX CRT Quantum - Satellite Telecommanding; General

COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
© Safran Data Systems
This document is the property of Safran Data Systems.
It cannot be duplicated or distributed without expressed written consent.
Page 132
3.5. Satellite Telecommanding
3.5.1. General
Satellite commanding is by the Telecommand Unit (TCU). The CORTEX CRT Quantum is a TC server for only
one client at a time. The satellite telecommanding protocol describes three types of TCP-IP messages:
 Satellite TC requests: the request includes a TC message to be transmitted to the spacecraft. The TC
message can be transmitted:
 in clear mode,
 or scrambled by an external TC Scrambler.
 TC instructions: they specify an action to be performed by the CORTEX CRT Quantum.
 « Wait & Verify » with Time-out and Retry instruction.
 « Execute » instruction.
 « Pause » instruction.
 « Wait for Absolute Time » instruction.
 « TCU Unlock » instruction.
 « NOP » instruction.
 « Stop Idling » instruction.
 « Group » instruction.
 « Set Delay » instruction.
 High level satellite TC requests:
 « Data + Execute » TC request.
Satellite TC requests and TC instructions are checked (via a check-sum) and acknowledged by the CORTEX
CRT Quantum (negative or positive command acknowledgement message).
In case of anomaly (bad check-sum), the connection is automatically closed by the CORTEX CRT Quantum after
sending an acknowledgement message with error code « 2 » to the Telecommand Client (socket closure will
avoid any potential synchronization problem). On socket closure, the CORTEX CRT Quantum automatically
flushes all pending TC instructions and satellite TC requests. Such anomaly is very unlikely to appear since all
data transfers are garanteed by the TCP-IP protocol.