Safran CORTEX CRT Quantum User Manual page 58

Time Code & Reference Clock Interface
1.6.9.
The CORTEX CRT Quantum must be connected to an external timing system in the following cases:

If the equipment is to be used for satellite ranging or accurate Doppler measurement. Due to the high level
of performance of the unit, an external reference clock (GPS-based for example) is required to ensure
phase shift and frequency measurement with the required accuracy.

If the equipment must be used for launch or transfer orbit support or control of LEO satellites (high
Doppler). In that case, it may be necessary to connect the chassis to an external time reference (GPS-
based IRIG-B code generator for example) for accurate time-tagging of the ranging, Doppler and telemetry
data.
The internal 10-MHz clock accuracy and stability on the Main Signal Processing board allows the CORTEX CRT
Quantum to fulfill its mission in most other station keeping scenarios.
The external reference clock frequency is either 5, 10 or 100 MHz and is received on two ports in active
redundancy. Clock selection (internal clock, external clock from port 1 or port 2) is programmable and offers
several priority scenarios. Frequency selection (5, 10 or 100 MHz) is automatic, at boot. However, performances
of the unit cannot be guaranteed if the external reference clock signal is corrupted or if the frequency is not
exactly 5, 10 or 100 MHz.
1.6.9.1. Time Code Decoding & Data Time-tagging

Input code

Amplitude

Impedance

Polarity and direction

Error by-pass

1-PPS input

Time tagging accuracy

Flywheel mode

Leap second & leap year management: Yes
© Safran Data Systems
COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
IRIG-B, NASA-36 or NTP
6 Vpp max
1 MΩ
Positive and forward
7 frames
Yes. TTL. Maximum rise and fall time: 20 ns
± 50 µs (without external 1-PPS), ± 100 ns (with external 1-PPS)
Yes
This document is the property of Safran Data Systems.
It cannot be duplicated or distributed without expressed written consent.
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec. 03, 2021Sept.
30, 2021
Page 33