Transmission Chain

The transmission process for a data vector \(u_t^{(0)}\) is given by the block diagram below.

Transmitter

__init__(fc=4000, fs=128000, Rb=400, carrier_length=0.082, preamble='2BEEEEBF', channel_encode=('nrz', 'man'), G=np.array([[121, 91]]), output_print=True, output_plot=True)

Encapsulates the entire transmission process in the PTT-A3 standard.

Parameters:

Name	Type	Description	Default
fc	float	Carrier frequency in Hz.	4000
fs	float	Sampling frequency in Hz.	128000
Rb	float	Bit rate in bps.	400
carrier_length	float	Prefix duration in seconds.	0.082
preamble	str	Preamble string in hex.	'2BEEEEBF'
channel_encode	tuple	Tuple with the type of encoding for channels I and Q respectively.	('nrz', 'man')
G	ndarray	Generation matrix for convolutional encoding.	array([[121, 91]])
output_print	bool	If True, prints intermediate vectors to the console.	True
output_plot	bool	If True, generates and saves the graphs of the intermediate processes.	True

Raises:

Type	Description
ValueError	If the sampling frequency is less than or equal to zero.
ValueError	If the bit rate is less than or equal to zero.
ValueError	If the carrier length is less than or equal to zero.
ValueError	If the preamble is empty.
ValueError	If the channel encoding types are not 'nrz' or 'manchester'.

Examples:

>>> import argos3
>>> import numpy as np 
>>> 
>>> fc = np.random.randint(10,80)*100
>>> print(fc)
2400
>>>
>>> transmitter = argos3.Transmitter(fc=fc, output_print=False, output_plot=False)
>>> t, s = transmitter.transmit(argos3.Datagram(pcdnum=1234, numblocks=1))
>>> 
>>> receiver = argos3.Receiver(fc=fc, output_print=False, output_plot=False)
>>> datagramRX, success = receiver.receive(s)
>>> 
>>> print(success)
True
>>> print(datagramRX.parse_datagram())
{
  "msglength": 1,
  "pcdid": 1234,
  "data": {
    "bloco_1": {
      "sensor_1": 37,
      "sensor_2": 198,
      "sensor_3": 9
    }
  },
  "tail": 7
}

Reference:
AS3-SP-516-274-CNES (sections 3.1 and 3.2)

datagram_build(datagram)

Prepares the datagram for transmission, returning the bit vector \(u_t\).

Returns:

Name	Type	Description
ut	ndarray	Bit vector of the datagram.

Examples:

• Bitstream Plot Example:

conv_encoder(ut)

Encodes the bit vector \(u_t\) using convolutional encoding, returning the bit vectors \(v_t^{(0)}\) and \(v_t^{(1)}\).

Parameters:

Name	Type	Description	Default
ut	ndarray	Bit vector to be encoded.	required

Returns:

Name	Type	Description
vt0	ndarray	Bit vector of channel I.
vt1	ndarray	Bit vector of channel Q.

Examples:

• Bitstream Plot Example:

scramble(vt0, vt1)

Scrambles the bit vectors \(v_t^{(0)}\) and \(v_t^{(1)}\), creating the shuffled vectors \(X[n]\) and \(Y[n]\).

Parameters:

Name	Type	Description	Default
vt0	ndarray	Bit vector of channel I.	required
vt1	ndarray	Bit vector of channel Q.	required

Returns:

Name	Type	Description
Xn	ndarray	Scrambled bit vector of channel I.
Yn	ndarray	Scrambled bit vector of channel Q.

Examples:

• Bitstream Plot Example:

preamble_build()

Generates the preamble vectors \(S_I[n]\) and \(S_Q[n]\).

Returns:

Name	Type	Description
sI	ndarray	Preamble vector of channel I.
sQ	ndarray	Preamble vector of channel Q.

Examples:

• Bitstream Plot Example:

mux(sI, sQ, X, Y)

Multiplexes the preamble vectors \(S_I[n]\) and \(S_Q[n]\) with the data vectors \(X[n]\) and \(Y[n]\), returning the multiplexed vectors \(X[n]\) and \(Y[n]\).

Parameters:

Name	Type	Description	Default
sI	ndarray	Preamble vector of channel I.	required
sQ	ndarray	Preamble vector of channel Q.	required
Xn	ndarray	Data vector of channel I.	required
Yn	ndarray	Data vector of channel Q.	required

Returns:

Name	Type	Description
Xn	ndarray	Multiplexed vector of channel I.
Yn	ndarray	Multiplexed vector of channel Q.

Examples:

• Bitstream Plot Example:

line_encoder(Xn, Yn)

Encodes the bit vectors \(X[n]\) and \(Y[n]\) using line coding (\(NRZ\)), returning the encoded symbol vectors \(I[n]\) and \(Q[n]\).

Parameters:

Name	Type	Description	Default
Xn	ndarray	Bit vector of channel I to be encoded.	required
Yn	ndarray	Bit vector of channel Q to be encoded.	required

Returns:

Name	Type	Description
In	ndarray	Encoded symbol vector of channel I.
Qn	ndarray	Encoded symbol vector of channel Q.

Examples:

• Signal Plot Example:

pulse_modulate(In, Qn)

Formats the line coded \(NRZ\) symbol vectors \(I[n]\) and \(Q[n]\) using RRC/Manchester filters, returning the formatted vectors \(d_I(t)\) and \(d_Q(t)\).

Parameters:

Name	Type	Description	Default
In	ndarray	Signal vector of channel \(I[n]\) to be formatted.	required
Qn	ndarray	Signal vector of channel \(Q[n]\) to be formatted.	required

Returns:

Name	Type	Description
dI	ndarray	Formatted vector of channel I.
dQ	ndarray	Formatted vector of channel Q.

Examples:

• Time Domain Plot Example:
• Frequency Domain Plot Example:

bandpass_modulate(dI, dQ)

Modulates the signal vectors \(d_I(t)\) and \(d_Q(t)\) using QPSK modulation, returning the modulated signal \(s(t)\).

Parameters:

Name	Type	Description	Default
dI	ndarray	Formatted vector of channel I.	required
dQ	ndarray	Formatted vector of channel Q.	required

Returns:

Name	Type	Description
t	ndarray	Time vector \(t\).
s	ndarray	Modulated signal \(s(t)\).

Examples:

• Time Domain Plot Example:
• Phase/Constellation Plot Example:
• Frequency Domain Plot Example:
• Pure Carrier Plot Example:

transmit(datagram)

Executes the entire transmission chain for a datagram, returning the modulated signal \(s(t)\) and the time vector \(t\).

Parameters:

Name	Type	Description	Default
datagram	Datagram	Instance of the datagram to be transmitted.	required

Returns:

Name	Type	Description
t	ndarray	Time vector \(t\).
s	ndarray	Modulated signal \(s(t)\).