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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 ax100_decode, u482c_decode
from ...hier.sync_to_pdu_packed import sync_to_pdu_packed
from ...utils.options_block import options_block
_syncword = '10010011000010110101000111011110'
class ax100_deframer(gr.hier_block2, options_block):
"""
Hierarchical block to deframe the GOMspace AX100 protocols.
The input is a float stream of soft symbols. The output are PDUs
with frames (most likely CSP frames).
Args:
mode: mode to use ('RS' or 'ASM') (string)
scrambler: scrambler to use, either 'CCSDS' or 'none'
(only for ASM mode) (str)
syncword_threshold: number of bit errors allowed in syncword (int)
syncword: syncword to use (str)
options: Options from argparse
"""
def __init__(self, mode, scrambler='CCSDS', syncword_threshold=None,
syncword=_syncword, options=None):
gr.hier_block2.__init__(
self,
'ax100_deframer',
gr.io_signature(1, 1, gr.sizeof_float),
gr.io_signature(0, 0, 0))
options_block.__init__(self, options)
if scrambler not in ['CCSDS', 'none']:
raise ValueError(f'invalid scrambler {scrambler}')
self.message_port_register_hier_out('out')
if syncword_threshold is None:
syncword_threshold = self.options.syncword_threshold
if mode not in ['RS', 'ASM']:
raise Exception("Unsupported AX100 mode. Use 'RS' or 'ASM'")
self.slicer = digital.binary_slicer_fb()
if mode == 'RS':
self.descrambler = digital.descrambler_bb(0x21, 0, 16)
self.deframer = sync_to_pdu_packed(
packlen=256 if mode == 'RS' else 258,
sync=syncword, threshold=syncword_threshold)
self.fec = (ax100_decode(self.options.verbose_fec) if mode == 'RS'
else u482c_decode(
self.options.verbose_fec, 0,
1 if scrambler == 'CCSDS' else 0, 1))
self._blocks = [self, self.slicer]
if mode == 'RS':
self._blocks.append(self.descrambler)
self._blocks += [self.deframer]
self.connect(*self._blocks)
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 AX100 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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