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
|
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright 2021 Daniel Estevez <daniel@destevez.net>
#
# This file is part of gr-satellites
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
import struct
from gnuradio import gr
import numpy as np
import pmt
# This block is based on the Universal SPUNTIX Protocol (USP)
# Protocol Description revision 1.04
# https://sputnix.ru/tpl/docs/amateurs/USP%20protocol%20description%20v1.04.pdf
class usp_ax25_crop(gr.basic_block):
"""
Crop a USP packet to obtain the encapsulated AX.25 frame
"""
def __init__(self):
gr.basic_block.__init__(
self,
name='usp_ax25_crop',
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
msg = pmt.u8vector_elements(msg)
length_field = msg[2:4]
length = struct.unpack('<H', bytes(length_field))[0]
msg_out = msg[4:][:length]
msg_out = pmt.init_u8vector(len(msg_out), msg_out)
msg_out = pmt.cons(pmt.car(msg_pmt), msg_out)
self.message_port_pub(pmt.intern('out'), msg_out)
|
