FGFS-4.1/adsb-out
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Refactor

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This commit is contained in:
nzkarit 2017-09-07 23:23:16 +12:00
parent 36b3527f58
commit 54db16eb83
3 changed files with 66 additions and 56 deletions
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1
ADSB_Encoder.py
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@ -64,5 +64,6 @@ if __name__ == "__main__":
samples_array = hackrf.hackrf_raw_IQ_format(df17_array)
SamplesFile = open("Samples.iq8s", "wb") # TODO make this a function and take the file name. Also have the option to run dd on it.
# TODO make it empty the file first.
SamplesFile.write(samples_array)
os.system("dd if=Samples.iq8s of=Samples_256K.iq8s bs=4k seek=63") # TODO make this a flag, also make it take the file name

68
ModeS.py
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@ -1,5 +1,5 @@
from location import *
from conversions import *
class ModeS:
"""This class handles the ModeS ADSB manipulation
"""
@ -38,7 +38,7 @@ class ModeS:
df17_str = "{0:02x}{1:02x}{2:02x}{3:02x}{4:02x}{5:02x}{6:02x}{7:02x}{8:02x}{9:02x}{10:02x}".format(*df17_even_bytes[0:11])
#print df17_str , "%X" % bin2int(crc(df17_str+"000000", encode=True)) , "%X" % get_parity(hex2bin(df17_str+"000000"), extended=True)
df17_crc = bin2int(crc(df17_str+"000000", encode=True))
df17_crc = self.bin2int(self.modes_crc(df17_str+"000000", encode=True))
df17_even_bytes.append((df17_crc>>16) & 0xff)
df17_even_bytes.append((df17_crc>> 8) & 0xff)
@ -60,10 +60,72 @@ class ModeS:
df17_odd_bytes.append((oddenclon ) & 0xff)
df17_str = "{0:02x}{1:02x}{2:02x}{3:02x}{4:02x}{5:02x}{6:02x}{7:02x}{8:02x}{9:02x}{10:02x}".format(*df17_odd_bytes[0:11])
df17_crc = bin2int(crc(df17_str+"000000", encode=True))
df17_crc = self.bin2int(self.modes_crc(df17_str+"000000", encode=True))
df17_odd_bytes.append((df17_crc>>16) & 0xff)
df17_odd_bytes.append((df17_crc>> 8) & 0xff)
df17_odd_bytes.append((df17_crc ) & 0xff)
return (df17_even_bytes, df17_odd_bytes)
###############################################################
# Copyright (C) 2015 Junzi Sun (TU Delft)
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# the polynominal generattor code for CRC
def modes_crc(self, msg, encode=False):
"""Mode-S Cyclic Redundancy Check
Detect if bit error occurs in the Mode-S message
Args:
msg (string): 28 bytes hexadecimal message string
encode (bool): True to encode the date only and return the checksum
Returns:
string: message checksum, or partity bits (encoder)
"""
GENERATOR = "1111111111111010000001001" # Currently don't know what is magic about this number
msgbin = list(self.hex2bin(msg))
if encode:
msgbin[-24:] = ['0'] * 24
# loop all bits, except last 24 piraty bits
for i in range(len(msgbin)-24):
# if 1, perform modulo 2 multiplication,
if msgbin[i] == '1':
for j in range(len(GENERATOR)):
# modulo 2 multiplication = XOR
msgbin[i+j] = str((int(msgbin[i+j]) ^ int(GENERATOR[j])))
# last 24 bits
reminder = ''.join(msgbin[-24:])
return reminder
def hex2bin(self, hexstr):
"""Convert a hexdecimal string to binary string, with zero fillings. """
scale = 16
num_of_bits = len(hexstr) * math.log(scale, 2)
binstr = bin(int(hexstr, scale))[2:].zfill(int(num_of_bits))
return binstr
def bin2int(self, binstr):
"""Convert a binary string to integer. """
return int(binstr, 2)

53
conversions.py
View File

@ -1,59 +1,6 @@
###############################################################
# Copyright (C) 2015 Junzi Sun (TU Delft)
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# the polynominal generattor code for CRC
import math
GENERATOR = "1111111111111010000001001"
def hex2bin(hexstr):
"""Convert a hexdecimal string to binary string, with zero fillings. """
scale = 16
num_of_bits = len(hexstr) * math.log(scale, 2)
binstr = bin(int(hexstr, scale))[2:].zfill(int(num_of_bits))
return binstr
def bin2int(binstr):
"""Convert a binary string to integer. """
return int(binstr, 2)
def crc(msg, encode=False):
"""Mode-S Cyclic Redundancy Check
Detect if bit error occurs in the Mode-S message
Args:
msg (string): 28 bytes hexadecimal message string
encode (bool): True to encode the date only and return the checksum
Returns:
string: message checksum, or partity bits (encoder)
"""
msgbin = list(hex2bin(msg))
if encode:
msgbin[-24:] = ['0'] * 24
# loop all bits, except last 24 piraty bits
for i in range(len(msgbin)-24):
# if 1, perform modulo 2 multiplication,
if msgbin[i] == '1':
for j in range(len(GENERATOR)):
# modulo 2 multiplication = XOR
msgbin[i+j] = str((int(msgbin[i+j]) ^ int(GENERATOR[j])))
# last 24 bits
reminder = ''.join(msgbin[-24:])
return reminder