3.2.4.3.1. CONV Encoder parameters¶
3.2.4.3.1.1. --enc-info-bits, -K 
¶
- Type:
integer
- Examples:
--enc-info-bits 64
Set the number of information bits \(K\).
The codeword size \(N\) is automatically deduced: \(N = 2 \times (K + \log_2(ts))\) where \(ts\) is the trellis size.
3.2.4.3.1.2. --enc-type¶
- Type:
text
- Allowed values:
CONVAZCWCOSETUSER- Default:
CONV- Examples:
--enc-type AZCW
Select the encoder type.
Description of the allowed values:
Value |
Description |
|---|---|
|
Select the standard feedforward convolutional encoder. |
|
See the common --enc-type parameter. |
|
See the common --enc-type parameter. |
|
See the common --enc-type parameter. |
Unlike the Codec RSC, the convolutional encoder is feedforward (non-recursive and non-systematic). The encoded output is interleaved: for \(K\) information bits and \(n_{\mathit{ff}} = \log_2(ts)\) memory elements, the encoder outputs \(X_0^{(0)}, X_0^{(1)}, X_1^{(0)}, X_1^{(1)}, [...], X_{K-1}^{(0)}, X_{K-1}^{(1)}, X_{0}^{(0)^t}, X_{0}^{(1)^t}, [...], X_{n_{\mathit{ff}}-1}^{(0)^t}, X_{n_{\mathit{ff}}-1}^{(1)^t}\), where \(X^{(0)}\) and \(X^{(1)}\) are respectively the outputs of the first and second generator polynomial, and \(t\) the tail bits used to drive the encoder back to the zero state.
3.2.4.3.1.3. --enc-poly¶
- Type:
text
- Default:
"{0171,0133}"- Examples:
--enc-poly "{023,033}"
Set the polynomials that define the feedforward convolutional code (or the trellis structure). The expected form is \(\{A,B\}\) where \(A\) and \(B\) are given in octal.
The default {0171,0133} corresponds to the industry-standard constraint
length 7, rate 1/2 NASA code, also used as the inner code of the Galileo E1B
signal.