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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright 2019 Daniel Estevez <daniel@destevez.net>
#
# This file is part of gr-satellites
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
from gnuradio import gr, digital
from ... import u482c_decode
from ...hier.sync_to_pdu_packed import sync_to_pdu_packed
from ...utils.options_block import options_block
_syncword = '11000011101010100110011001010101'
class u482c_deframer(gr.hier_block2, options_block):
"""
Hierarchical block to deframe the GOMspace U482C protocol.
The input is a float stream of soft symbols. The output are PDUs
with frames (most likely CSP frames).
Args:
syncword_threshold: number of bit errors allowed in syncword (int)
options: Options from argparse
"""
def __init__(self, syncword_threshold=None, options=None):
gr.hier_block2.__init__(
self,
'u428c_deframer',
gr.io_signature(1, 1, gr.sizeof_float),
gr.io_signature(0, 0, 0))
options_block.__init__(self, options)
self.message_port_register_hier_out('out')
if syncword_threshold is None:
syncword_threshold = self.options.syncword_threshold
self.slicer = digital.binary_slicer_fb()
self.deframer = sync_to_pdu_packed(
packlen=258, sync=_syncword, threshold=syncword_threshold)
self.fec = u482c_decode(self.options.verbose_fec, -1, -1, -1)
self.connect(self, self.slicer, self.deframer)
self.msg_connect((self.deframer, 'out'), (self.fec, 'in'))
self.msg_connect((self.fec, 'out'), (self, 'out'))
_default_sync_threshold = 4
@classmethod
def add_options(cls, parser):
"""
Adds U482C deframer specific options to the argparse parser
"""
parser.add_argument(
'--syncword_threshold', type=int,
default=cls._default_sync_threshold,
help='Syncword bit errors [default=%(default)r]')
parser.add_argument(
'--verbose_fec', action='store_true', help='Verbose FEC decoder')
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