Frame Synchronizer Operating Modes; Afl: Anti False Lock - Safran CORTEX CRT Quantum User Manual

3.3.8.3. Frame Synchronizer Operating Modes

The frame synchronizer can operate in three modes:

In Normal mode, each reconstructed minor frame (including the synchronization word) is
checked (if the CRC or checksum verification has been activated) and then embedded in an
ETHERNET packet which is time-tagged and transmitted to the Telemetry Clients (whatever
the result of the CRC or checksum verification). The frame verification result (OK or NOK) is
reported to the Monitoring Clients (Frame Check alarm). It is also reported to the Telemetry
Clients (frame check result in each telemetry message). The Frame Check alarm is not
latched: it is automatically cleared on reception of a good frame.

As per the Normal mode (compatibility with the VME-based CORTEX).

Test mode 2 differs from Test mode 1 in that the telemetry frames are not transmitted to the
Telemetry Clients.

3.3.8.4. AFL: Anti False Lock

For false lock mitigation, an anti-false lock functionality has been added (SPS e5r23 and higher). See STI
100013_TTC Telemetry Unit table, offset 18.
Two different AFL modes are available:

It consists in reopening the carrier phase-lock loop if frame synchronization process has not
found the sync word (ASM) after a programmable delay. The timer starts when the IFR locks.
The delay to lock the PSK and Bit Synchronizer should therefore be taken into account.
If the Telemetry Unit is linked to a disabled Diversity Combining Unit (DCU), the AFL
process will reopen the carriers' phase-lock loops independently.
If the Telemetry Unit is linked to an enabled Diversity Combining Unit (DCU), the AFL
process will open both carriers' phase-lock loops at the same time (restart diversity).

It consists in reopening the sub-carrier phase-lock loop if frame synchronization process has
not found the sync word (ASM) after a programmable delay.
Only available in Video Mode. (Telemetry Unit in Low or High rate mode)
If more than one telemetry unit is linked to an IFR (or a DCU), we need all the frame synchronizers on Search to
activate the AFL treatment. If this condition is met, we will take the maximum delay from the telemetry units with
the Frame Synchronization enabled.
In Video Post-detection mode, we have 2 available outputs on the DCU. So the link between TMU and IFR
depends on Output 1 and 2 values.
© Safran Data Systems
COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
In Normal Mode:
In Test mode 1:
In Test mode 2:
Standard AFL:
AFL PSK (SPS e5r27 and higher):
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It cannot be duplicated or distributed without expressed written consent.
Safran Data Systems
.
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
Page 97