Psk Ambiguity Solving - Safran CORTEX CRT Quantum User Manual

The frame synchronizer synchronizes the frame in accordance with the SYN, CTL, LTS and Bit Slip parameters
provided to it:
SW 7,F incorrect
NT
S: SEARCH
C: CHECK
L: LOCK
F: FLYWHEEL
SW: Synchronisation Word
NT : frame not transmitted
T : frame transmitted
Scenario: CTL = 2, LTS = 3
Received telemetry:
Frames 0 to 2: SW correct
Frames 3 to 7: SW incorrect
Frames 8 to A: SW correct
Frames B to F: SW incorrect

3.3.8.2. PSK Ambiguity Solving

PSK ambiguity solving is performed by the frame synchronizer during the SEARCH phase (and only during this
phase). If the comparison between the expected synchronization word and a given window on the received
NRZL data stream is not successful, a second comparison is made after inversion of the telemetry data. If this
second comparison is successful (to within n bits), the signal inversion is confirmed and the frame synchronizer
switches to the CHECK phase.
© Safran Data Systems
COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
SW 0,8
correct
NT
(1)
NT
S
SW 6,E
incorrect
NT NT
F
Figure 45: Frame Synchronization Process
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SW 1,9
C
correct
NT
C
(1)
NT
(3)
T
(3)
T
F
SW 5,D
incorrect
T
Dotted lines: alternate scenario (different frame contents)
(1): return to search mode if SW incorrect
(2): stay in lock mode while SWs are correct
(3): return to lock mode if SW correct
Safran Data Systems
.
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
SW 2,A
correct
NT
(2)
T
L
(3) SW 3,B
T
incorrect
T
F
SW 4,C
incorrect
T
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