Sync Word Length ≤ 32 Bits - Safran CORTEX RTR NeXt Series User Manual

 LOCK phase (L) :
In the LOCK mode, the frame synchronizer merely checks the occurrence of a new synchronization word (to within
n errors) every frame. The window in which the synchronization word should be found is enlarged by  N bits (N =
bit slip parameter = 0, 1, 2 or 3 bits) to cope with potential bit slip in the telemetry demodulation process.
 FLYWHEEL phase (F) :
Transmission errors (signal heavily affected by noise) or loss of demodulator lock may occur : the frame
synchronizer will then only return to SEARCH mode after « j » consecutive occurrences of incorrect synchronization
words (number of errors greater than the synchronization threshold). « j » is programmable between 0 and 15
(inclusive) referred to as the LTS (Lock-To-Search) threshold.
Note : Ambiguity Resolution
Ambiguity resolution 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.
Sync Word Length ≤ 32 bits
6.12.1
Following are some examples of frame synchronizer configurations with Synchronization word length
lower or equal to 32 bits. In the following examples, we are not considering the different threshold for
synchronization.
Example 1: Sync Word length = 32 bits and Words of 8 bits
Frame description:
Sync = 1ACFFC1D
Frame Sync Configuration:
© Safran Data Systems – IMP000074 e14r1
Radio Telemetry Receiver
User's Manual
Data length = 1275 words of 8 bits
Total length = 4 + 1275 = 1279 Words
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Ref. D104004
Is.Rev 07
Previous Ref.: DTU000567
Date: 21/06/2021
Safran Data Systems
.
Page 79