Line Encoder

__init__(method='NRZ')

Initializes the line encoder with the specified encoding method, used to encode the bitstream as \(X[n]\) and \(Y[n]\), returning the symbol stream \(I[n]\) and \(Q[n]\).

Parameters:

Name	Type	Description	Default
method	str	Encoding method, 'NRZ' or 'Manchester'.	'NRZ'

Raises:

Type	Description
ValueError	If the encoding method is not supported.

Examples:

>>> import argos3
>>> import numpy as np
>>> 
>>> Xn = np.random.randint(0, 2, 20)
>>> Yn = np.random.randint(0, 2, 20)
>>> 
>>> print(Xn)
[1 0 1 1 0 0 1 0 0 0 0 0 0 0 1 0 1 1 0 0]
>>> print(Yn)
[1 0 0 0 0 0 1 0 1 0 0 0 0 1 1 1 0 1 1 1]
>>> 
>>> encoder_nrz = argos3.Encoder(method="NRZ")
>>> encoder_man = argos3.Encoder(method="Manchester")
>>> 
>>> In = encoder_nrz.encode(Xn)
>>> Qn = encoder_man.encode(Yn)
>>> 
>>> print(In)
[ 1 -1  1  1 -1 -1  1 -1 -1 -1 -1 -1 -1 -1  1 -1  1  1 -1 -1]
>>> 
>>> print(Qn)
[ 1 -1 -1  1 -1  1 -1  1 -1  1 -1  1  1 -1 -1  1  1 -1 -1  1 -1  1 -1  1
 -1  1  1 -1  1 -1  1 -1 -1  1  1 -1  1 -1  1 -1]
>>> 
>>> Xn_prime = encoder_nrz.decode(In)
>>> Yn_prime = encoder_man.decode(Qn)
>>> 
>>> print(Xn_prime)
[1 0 1 1 0 0 1 0 0 0 0 0 0 0 1 0 1 1 0 0]
>>> print(Yn_prime)
[1 0 0 0 0 0 1 0 1 0 0 0 0 1 1 1 0 1 1 1]

• Bitstream Plot Example:

Reference:
AS3-SP-516-274-CNES (section 3.2.4)

encode(bitstream)

Encodes the bitstream using the specified encoding method. The encoding process is given by the expressions below corresponding to each method.

\[ \begin{equation} \begin{aligned} K[n] &= \begin{cases} +1, & \text{if } k[n] = 1 \\ -1, & \text{if } k[n] = 0 , \end{cases} &\quad\quad K[n] &= \begin{cases} +1,-1, & \text{if } k[n] = 1 \\ -1, +1, & \text{if } k[n] = 0 . \end{cases} \end{aligned} \end{equation} \]

Where

• \(k[n]\): Input bitstream.
• \(K[n]\): Output symbol stream.

Parameters:

Name	Type	Description	Default
bitstream	ndarray	Input bitstream.	required

Returns:

Name	Type	Description
out	ndarray	Encoded symbol stream.

decode(encodedstream)

Decodes the symbol stream using the specified encoding method. The decoding process is given by the expressions below corresponding to each method.

\[ \begin{equation} \begin{aligned} k[n] &= \begin{cases} 1, & \text{if } K[n] = +1 \\ 0, & \text{if } K[n] = -1 \end{cases} &\quad\quad k[n] &= \begin{cases} 1, & \text{if } K[n] = +1, -1 \\ 0, & \text{if } K[n] = -1, +1 \end{cases} \end{aligned} \end{equation} \]

Where

• \(K[n]\): Input symbol stream
• \(k[n]\): Output bitstream.

Parameters:

Name	Type	Description	Default
encoded_stream	ndarray	Input symbol stream.	required

Returns:

Name	Type	Description
out	ndarray	Decoded bitstream.