Safran CORTEX Series - PCM Decoding; DNRZ, QPSK Decoding (DQPSK); CCSDS Recommended DNRZ Code in QPSK Mode

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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Page 91
PCM Decoding 3.3.4
The following codes are supported: NRZ-L/M/S, DNRZ, Bi-P-L/M/S.
When Viterbi decoding is not used, DNRZ is required for ambiguity resolution in QPSK and OQPSK
mode. Several possible DNRZ schemes can be defined, according to the demodulation (QPSK, or
OQPSK).
DNRZ, QPSK Decoding (DQPSK) 3.3.4.1
Several DNRZ algorithms are possible for ambiguity resolution in QPSK mode. The DNRZ code
(algorithm) value can be programmed via Cortex HDR ICD parameter, using examples in next two
sections (CCSDS recommended code and non-CCSDS codes).
CCSDS Recommended DNRZ Code in QPSK Mode 3.3.4.1.1
CCSDS recommendation for DQPSK is:
1111   outininoutininoutininoutininout QQIIQIQQIIQII
1111   outininoutininoutininoutininout IQIQQIIQIQQIQ
This is equivalent to the following DQPSK decoding look-up table:
I
dl
[n-1]
Q
dl
[n-1]
I
dl
[n]
Q
dl
[n]
in[n]I
ˆ
in[n]Q
ˆ
0
0
0
0
1
1
0
0
0
1
1
0
0
0
1
0
0
1
0
0
1
1
0
0
0
1
0
0
0
1
0
1
0
1
1
1
0
1
1
0
0
0
0
1
1
1
1
0
1
0
0
0
1
0
1
0
0
1
0
0
1
0
1
0
1
1
1
0
1
1
0
1
1
1
0
0
0
0
1
1
0
1
0
1
1
1
1
0
1
0
1
1
1
1
1
1