1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright 2018 Daniel Estevez <daniel@destevez.net>
#
# This file is part of gr-satellites
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
from gnuradio import gr
import numpy as np
import pmt
def reflect_bytes(x):
return np.fliplr(x[:x.size//8*8].reshape((-1, 8))).ravel()
def destuff(x):
y = list()
run = 0
for i, bit in enumerate(x):
if run == 5:
if bit == 1:
# Unexpected long run of ones
return
else:
run = 0
elif bit == 0:
run = 0
y.append(bit)
elif bit == 1:
run += 1
y.append(bit)
return np.array(y, dtype='uint8')
def descramble(x):
y = np.concatenate((np.zeros(17, dtype='uint8'), x))
z = y[:-17] ^ y[5:-12] ^ y[17:]
return z
def nrzi_decode(x):
return x ^ np.concatenate((np.zeros(1, dtype='uint8'), x[:-1])) ^ 1
class eseo_line_decoder(gr.basic_block):
"""docstring for block eseo_line_decoder"""
def __init__(self):
gr.basic_block.__init__(
self,
name='eseo_line_decoder',
in_sig=[],
out_sig=[])
self.message_port_register_in(pmt.intern('in'))
self.set_msg_handler(pmt.intern('in'), self.handle_msg)
self.message_port_register_out(pmt.intern('out'))
def handle_msg(self, msg_pmt):
msg = pmt.cdr(msg_pmt)
if not pmt.is_u8vector(msg):
print('[ERROR] Received invalid message type. Expected u8vector')
return
packet = np.array(pmt.u8vector_elements(msg), dtype='uint8')
# Decode ESEO "line coding"
packet = np.unpackbits(packet)
packet = destuff(packet)
if packet is None:
return
packet = descramble(packet)
packet = nrzi_decode(packet)
packet = reflect_bytes(packet)
# Remove dummy padding
cutbits = packet.size % 8
if cutbits:
packet = packet[:-cutbits]
packet = np.packbits(packet)
packet = bytes(packet)
self.message_port_pub(pmt.intern('out'),
pmt.cons(pmt.car(msg_pmt),
pmt.init_u8vector(len(packet), packet)))
|
