Reception Chain

The reception chain is divided into two steps, carrier detection, responsible for verifying the received signal and identifying for each time segment the carriers present, and the receiver chain, responsible for receiving a signal segment and performing the reception process to recover the data vector \(u_t^{(0)}\), as shown in the block diagram below.

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Carrier Detector

Initializes a carrier detector, used to detect possible carriers in the received signal.

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Parameters:

Name	Type	Description	Default
`fs`	`float`	Sampling frequency [Hz]	`128000`
`seg_ms`	`float`	Duration of each segment [ms]	`10.0`
`threshold`	`float`	Power threshold for detection	`-10`
`freq_window`	`tuple[float, float]`	Frequency interval (`f_min`, `f_max`). Frequencies outside this interval will be discarded.	`(0, 10000)`
`bandwidth`	`float`	Bandwidth of span [Hz], used to ignore other frequencies that can be confirmed.	`1600`
`history`	`int`	Number of previous segments to consider for carrier detection.	`4`

Raises:

Type	Description
`ValueError`	If the sampling frequency is less than or equal to zero.
`ValueError`	If the segment duration is less than or equal to zero.

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))
>>> 
>>> channel = argos3.Channel(duration=1, noise_mode="ebn0", noise_db=20)
>>> channel.add_signal(s, position_factor=0.5)
>>> channel.add_noise()
>>> st = channel.channel
>>> 
>>> detector = argos3.CarrierDetector(seg_ms=10, threshold=-15)
>>> detector.detect(st.copy())
>>> detections = detector.return_channels()
>>>
>>> print(detections)
[(np.float64(2400.0), 41, 65)]
>>>                   
>>> first_sample = int((detections[0][1] - 5) * detector.fs * detector.seg_s)
>>> last_sample = int(detections[0][2] * detector.fs * detector.seg_s)
>>> st_prime = st[first_sample:last_sample]
>>> 
>>> receiver = argos3.Receiver(fc=detections[0][0], output_print=False, output_plot=False)
>>> datagramRX, success = receiver.receive(st_prime)
>>> 
>>> 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
}

Waterfall Diagram:
Frequency Domain Segment:
Waterfall Detection Diagram:
Waterfall Decision Diagram:

Reference:
AS3-SP-516-2097-CNES (Section 3.3)

Reception Chain

`init(fs=128000, Rb=400, fc=None, lpf_cutoff=600, preamble='2BEEEEBF', channel_encode=('nrz', 'man'), G=np.array([[121, 91]]), output_print=True, output_plot=True)`

Class that encapsulates the entire reception process in the ARGOS-3 standard.

Parameters:

Name	Type	Description	Default
`fs`	`int`	Sampling frequency in Hz.	`128000`
`Rb`	`int`	Bit rate in bps.	`400`
`fc`	`int`	Carrier frequency in Hz.	`None`
`lpf_cutoff`	`int`	Cutoff frequency of the low-pass filter in Hz.	`600`
`preamble`	`str`	String of preamble in hex.	`'2BEEEEBF'`
`channel_encode`	`tuple`	Tuple with the type of encoding of channels I and Q respectively.	`('nrz', 'man')`
`G`	`ndarray`	Generation matrix for convolutional encoding.	`array([[121, 91]])`
`output_print`	`bool`	If `True`, prints the 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 encoding types are not 'nrz' or 'manchester'.

Reference:
AS3-SP-516-2097-CNES (section 3.1 and 3.2)

`bandpass_demodulate(s_prime, t)`

Demodulates the received signal \(s'(t)\) with noise \(r(t)\), returning the signals \(dX'_{I}(t)\) and \(dY'_{Q}(t)\).

Parameters:

Name	Type	Description	Default
`s_prime`	`ndarray`	Received signal \(s'(t)\) to be demodulated.	required
`t`	`ndarray`	Time vector.	required

Returns:

Name	Type	Description
`dX_prime`	`ndarray`	Demodulated signal \(dX'_{I}(t)\).
`dY_prime`	`ndarray`	Demodulated signal \(dY'_{Q}(t)\).

Examples:

Time Domain Plot Example:
Frequency Domain Plot Example:

`low_pass_filter(dX_prime, dY_prime, t)`

Applies the low-pass filter (LPF) with impulse response \(h(t)\) to the signals \(dX'(t)\) and \(dY'(t)\), returning the filtered signals \(d_{I}'(t)\) and \(d_{Q}'(t)\).

Parameters:

Name	Type	Description	Default
`dX_prime`	`ndarray`	Signal \(dX'(t)\) to be filtered.	required
`dY_prime`	`ndarray`	Signal \(dY'(t)\) to be filtered.	required
`t`	`ndarray`	Time vector.	required

Returns:

Name	Type	Description
`dI_prime`	`ndarray`	Signal \(d_{I}'(t)\) filtered.
`dQ_prime`	`ndarray`	Signal \(d_{Q}'(t)\) filtered.

Examples:

Time Domain Plot Example:
Frequency Domain Plot Example:

`matched_filter(dI_prime, dQ_prime, t)`

Applies the matched filter with impulse response \(g(-t)\) to the signals \(d_{I}'(t)\) and \(d_{Q}'(t)\), returning the filtered signals \(I'(t)\) and \(Q'(t)\).

Parameters:

Name	Type	Description	Default
`dI_prime`	`ndarray`	Signal \(d'_{I}(t)\) to be filtered.	required
`dQ_prime`	`ndarray`	Signal \(d'_{Q}(t)\) to be filtered.	required
`t`	`ndarray`	Time vector.	required

Returns:

Name	Type	Description
`It_prime`	`ndarray`	Signal \(I'(t)\) filtered.
`Qt_prime`	`ndarray`	Signal \(Q'(t)\) filtered.

Examples:

Time Domain Plot Example:
Frequency Domain Plot Example:

`synchronizer(It_prime, Qt_prime)`

Performs the signal synchronization, returning the synchronized signal.

Parameters:

Name	Type	Description	Default
`It_prime`	`ndarray`	Signal \(I'(t)\) to be synchronized.	required
`Qt_prime`	`ndarray`	Signal \(Q'(t)\) to be synchronized.	required

Returns:

Name	Type	Description
`delayI`	`float`	Delay of the signal \(I'(t)\).
`delayQ`	`float`	Delay of the signal \(Q'(t)\).

Examples:

Time Domain Plot Example:
Correlation Module Plot Example:

`sampler(It_prime, Qt_prime, t)`

Performs the decision (sampling and quantization) of the signals \(I'(t)\) and \(Q'(t)\), returning the symbol vectors \(I'[n]\) and \(Q'[n]\).

Parameters:

Name	Type	Description	Default
`It_prime`	`ndarray`	Signal \(I'(t)\), matched filtered.	required
`Qt_prime`	`ndarray`	Signal \(Q'(t)\), matched filtered.	required
`t`	`ndarray`	Time vector.	required

Returns:

Name	Type	Description
`In_prime`	`ndarray`	Symbol vector \(I'[n]\) sampled and quantized.
`Qn_prime`	`ndarray`	Symbol vector \(Q'[n]\) sampled and quantized.

Examples:

Time Domain Plot Example:
Constellation Plot Example:
Phase Plot Example:

`line_decoder(In_prime, Qn_prime)`

Decodes the symbol vectors \(I'[n]\) and \(Q'[n]\), returning the bit vectors \(X'[n]\) and \(Y'[n]\).

Parameters:

Name	Type	Description	Default
`In_prime`	`ndarray`	Symbol vector \(I'[n]\) quantized.	required
`Qn_prime`	`ndarray`	Symbol vector \(Q'[n]\) quantized.	required

Returns:

Name	Type	Description
`Xn_prime`	`ndarray`	Bit vector \(X'[n]\) line decoded.
`Yn_prime`	`ndarray`	Bit vector \(Y'[n]\) line decoded.

Examples:

Time Domain Plot Example:

`unscramble(Xn_prime, Yn_prime)`

Unscrambles the bit vectors \(X'[n]\) and \(Y'[n]\), returning the bit vectors \(v_{t}^{(0)} \prime\) and \(v_{t}^{(1)} \prime\).

Parameters:

Name	Type	Description	Default
`Xn_prime`	`ndarray`	Bit vector \(X'[n]\) line decoded.	required
`Yn_prime`	`ndarray`	Bit vector \(Y'[n]\) line decoded.	required

Returns:

Name	Type	Description
`vt0_prime`	`ndarray`	Bit vector \(v_{t}^{(0)} \prime\) unscrambled.
`vt1_prime`	`ndarray`	Bit vector \(v_{t}^{(1)} \prime\) unscrambled.

Examples:

Time Domain Plot Example:

`conv_decoder(vt0_prime, vt1_prime)`

Decodes the bit vectors \(v_{t}^{(0)} \prime\) and \(v_{t}^{(1)} \prime\), returning the bit vector \(u_{t}'\).

Parameters:

Name	Type	Description	Default
`vt0_prime`	`ndarray`	Bit vector \(v_{t}^{(0)} \prime\) unscrambled.	required
`vt1_prime`	`ndarray`	Bit vector \(v_{t}^{(1)} \prime\) unscrambled.	required

Returns:

Name	Type	Description
`ut_prime`	`ndarray`	Bit vector \(u_{t}'\) decoded.

Examples:

Time Domain Plot Example:

`datagram_parser(ut_prime)`

Receives a decoded bit vector \(u_{t}'\) and returns a datagram in the ARGOS-3 format, or the bit vector \(u_{t}'\) if there is an error.

Parameters:

Name	Type	Description	Default
`ut_prime`	`ndarray`	Bit vector \(u_{t}'\) decoded.	required

Returns:

Name	Type	Description
`datagram`	`ndarray`	Datagram generated, or the bit vector \(u_{t}'\) if there is an error.
`success`	`bool`	Indicates if the operation was successful.

Examples:

Time Domain Plot Example:

`receive(s_prime)`

Receives a signal \(s(t)\) and returns the result of the reception.

Parameters:

Name	Type	Description	Default
`s_prime`	`ndarray`	Signal \(s(t)\) received.	required

Returns:

Name	Type	Description
`datagramRX`	`ndarray`	Datagram generated, or the bit vector \(u_{t}'\) if there is an error.

Reception Chain

Carrier Detector

Reception Chain

__init__(fs=128000, Rb=400, fc=None, lpf_cutoff=600, preamble='2BEEEEBF', channel_encode=('nrz', 'man'), G=np.array([[121, 91]]), output_print=True, output_plot=True)

bandpass_demodulate(s_prime, t)

low_pass_filter(dX_prime, dY_prime, t)

matched_filter(dI_prime, dQ_prime, t)

synchronizer(It_prime, Qt_prime)

sampler(It_prime, Qt_prime, t)

line_decoder(In_prime, Qn_prime)

unscramble(Xn_prime, Yn_prime)

conv_decoder(vt0_prime, vt1_prime)

datagram_parser(ut_prime)

receive(s_prime)

`init(fs=128000, Rb=400, fc=None, lpf_cutoff=600, preamble='2BEEEEBF', channel_encode=('nrz', 'man'), G=np.array([[121, 91]]), output_print=True, output_plot=True)`

`bandpass_demodulate(s_prime, t)`

`low_pass_filter(dX_prime, dY_prime, t)`

`matched_filter(dI_prime, dQ_prime, t)`

`synchronizer(It_prime, Qt_prime)`

`sampler(It_prime, Qt_prime, t)`

`line_decoder(In_prime, Qn_prime)`

`unscramble(Xn_prime, Yn_prime)`

`conv_decoder(vt0_prime, vt1_prime)`

`datagram_parser(ut_prime)`

`receive(s_prime)`