HIGH DATA RATE RECEIVER
HDR-4G+ USER’S MANUAL
Ref. DTU 100782
Is.Rev 3.5
Date: June 1, 2021
© Safran Data Systems – IMP000074 e14r1
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It cannot be duplicated or distributed without expressed written consent.
When the synchronization input is set to I ( respectively Q) (see section above)., the frame
synchronizer searches the synchronization word on I and Q channels (at Frame synchronizer input)
and automatically route the selected channel to the I (respectively Q) ECL output.
Ambiguity resolved (note 3)
Note 1: Same bit rate but asynchronous I and Q clocks.
Note 2: Enables to retrieve the original data stream even if the on-board data process is unknown to
the operator.
Note 3: Providing that correct 8PSK de-mapping (normal or Gray) has been selected.
CCSDS Data De-randomizer 3.4.3
Randomization technique can be used:
- to maintain bit or symbol synchronization on the telemetry processing chain, by always having a
minimum bit transition density on the received telemetry signal,
- to avoid a false carrier lock that can occur on a modulated signal with periodic data,
- to avoid ambiguous data patterns that allow decoder false lock.
De-randomization by the CORTEX
HDR complies to the CCSDS recommendation 101.0-B-3 (Blue
Book - May 1992). The pseudo-random sequence is generated using the following polynomial:
h(x) = x8 + x7 + x5 + x3 + 1
Customized de-randomization can also be used (refer to the following paragraph).
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