GR712RC-UM, Jun 2017, Version 2.9 211 www.cobham.com/gaisler
GR712RC
27.6 Physical Layer
27.6.1 Non-Return-to-Zero Mark encoder
The Non-Return-to-Zero Mark encoder (NRZ) encodes differentially a bit stream from preceding
encoders according to [ECSS-E-ST-50-05C]. The waveform is shown in figure 87
Both data and the Attached Synchronization Marker (ASM) are affected by the coding. When the
encoder is not enabled, the bit stream is by default non-return-to-zero level encoded.
27.6.2 Split-Phase Level modulator
The Split-Phase Level modulator (SP) modulates a bit stream from preceding encoders according to
[ECSS-E-ST-50-05C]. The waveform is shown in figure 88.
Both data and the Attached Synchronization Marker (ASM) are effected by the modulator. The modu-
lator will increase the output bit rate with a factor of two.
27.6.3 Sub-Carrier modulator
The Sub-Carrier modulator (SC) modulates a bit stream from preceding encoders according to
[ECSS-E-ST-50-05C], which is Binary Phase Shift Key modulation (BPSK) or Phase Shift Key
Square.
The sub-carrier modulation frequency is programmable. The symbol rate clock be divided to a degree
2
15
. The divider can be configured during operation to divide the symbol rate clock frequency from 1/
2 to 1/2
15
. The phase of the sub-carrier is programmable, selecting which phase 0º or 180º should cor-
respond to a logical one on the input.
x
6
x
5
x
4
x
3
x
2
x
1
data in data out
G1
G2
Puncture
data out G1
data out G2
Figure 86. Punctured convolutional encoder
Symbol:
NRZ-L
NRZ-M
111100 0 0
Figure 87. NRZ-L and NRZ-M waveform
Symbol:
SP-L
111100 0 0
Figure 88. SP-L waveform
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