Convolutional Coder; Figure 20: Differential Coder And Modulo-8 Adder Principle; Figure 21: Convolutional Coder Recommended For High Data Rates - Safran CORTEX Series User Manual

For all the bits non concerned by the differential encoding, we have then:
3.3.7.2.2

Convolutional Coder

The convolutional coder used to implement the trellis is depicted in Figure 21. This code corresponds
to one of the "best" codes for phase transparency.
The systematic coder is implemented with the following characteristics:
 number of states: 64 states,
 constraint length: K = 7
The convolutional encoder is specified by the following polynomial in octal: h
h = 103. Figure 21 shows the recommended convolutional encoder. The shift registers of the encoder
0
are clocked at the rate of R

Figure 21: Convolutional Coder Recommended for High Data Rates

The number of coded bits is the same for the four modulation efficiencies (i.e., the same structure is
used for 2, 2.25, 2.5, and 2.75 bits/channel-symbol), only the number of uncoded bits is changed. The
advantage of this coder is its optimized performance and the reduced internal rate which is equal to
1/8, 1/9, 1/10, or 1/11 of the information rate.
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HIGH DATA RATE RECEIVER
HDR-4G+ USER'S MANUAL
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Figure 20: Differential Coder and Modulo-8 Adder Principle

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Safran Data Systems
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x w k m 1
k k
= 050, h = 024, h = 006,
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