Features:
- initial support for multiples tracks simulation Enhancements: - code profiling and optimization - faster lookup table based ppm + IQ generation - faster CRC24 computations - frame encoding Bug fixes: - callsign encoding - typos
This commit is contained in:
Mathieu Peyréga
@@ -1,23 +1,39 @@
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""" This class is responsible for low level encoding of IQ sample
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This program is free software: you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program. If not, see <http://www.gnu.org/licenses/>.
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"""
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from CustomDecorators import *
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import numpy
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@Singleton
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class ADSBLowLevelEncoder:
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"""
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Hamming and Manchester Encoding example
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Author: Joel Addison
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Date: March 2013
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Functions to do (7,4) hamming encoding and decoding, including error detection
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and correction.
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Manchester encoding and decoding is also included, and by default will use
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least bit ordering for the byte that is to be included in the array.
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"""
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def __init__(self):
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self.adsb_frame_preamble = [0xA1,0x40]
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self.adsb_frame_pause = [0]*70
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self._adsb_frame_preamble = [0xA1,0x40]
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self._adsb_frame_pause = [0]*4
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# Build a manchester encoding lookup table
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self._manchester_lookup = []
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for i in range(256):
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me = self.manchester_encode(i)
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self._manchester_lookup.append([127*val for pair in zip(me, me) for val in pair])
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# Build preamble and pause manchester encoded versions
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me_bits = numpy.unpackbits(numpy.asarray(self._adsb_frame_preamble, dtype=numpy.uint8))
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self._adsb_frame_preamble_IQ = [127*val for pair in zip(me_bits, me_bits) for val in pair]
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self._adsb_frame_pause_IQ = self._adsb_frame_pause*16
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self._len_pre_IQ = len(self._adsb_frame_preamble_IQ)
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self._len_pause_IQ = len(self._adsb_frame_pause_IQ)
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###############################################################
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# Further work on fork
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# Copyright (C) 2017 David Robinson
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@@ -38,65 +54,62 @@ class ADSBLowLevelEncoder:
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# Encode byte
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for i in range(7, -1, -1):
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if self.extract_bit(byte, i):
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manchester_encoded.extend([0,1])
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else:
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manchester_encoded.extend([1,0])
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else:
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manchester_encoded.extend([0,1])
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return manchester_encoded
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def frame_1090es_ppm_modulate(self, even, odd = []):
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def frame_1090es_ppm_modulate_IQ(self, even, odd = []):
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"""
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Args:
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even and odd: The data frames that need to be converted to PPM
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Returns:
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The bytearray of the PPM data
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The bytearray of the IQ samples for PPM modulated data
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"""
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ppm = [ ]
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length_even = len(even)
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length_odd = len(odd)
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if (length_even != 0 and length_odd == 0):
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IQ = bytearray(32*length_even+2*self._len_pause_IQ+self._len_pre_IQ)
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pos = self._len_pause_IQ
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IQ[pos:pos+self._len_pre_IQ] = self._adsb_frame_preamble_IQ
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pos += self._len_pre_IQ
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if (length_even != 0):
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ppm.extend(self.adsb_frame_pause) # pause
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ppm.extend(self.adsb_frame_preamble) # preamble
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tmp = []
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for b in even:
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tmp.extend(self._manchester_lookup[b])
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IQ[pos:pos+32*length_even] = tmp
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for i in range(length_even):
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word16 = numpy.packbits(self.manchester_encode(~even[i]))
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ppm.extend(word16[0:2])
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ppm.extend(self.adsb_frame_pause) # pause
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return IQ
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if (length_odd != 0):
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ppm.extend(self.adsb_frame_pause) # pause
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ppm.extend(self.adsb_frame_preamble) # preamble
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elif (length_even != 0 and length_odd != 0):
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IQ = bytearray(32*(length_even+length_odd)+2*self._len_pre_IQ+3*self._len_pause_IQ)
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pos = self._len_pause_IQ
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IQ[pos:pos+self._len_pre_IQ] = self._adsb_frame_preamble_IQ
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pos += self._len_pre_IQ
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for i in range(length_odd):
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word16 = numpy.packbits(self.manchester_encode(~odd[i]))
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ppm.extend(word16[0:2])
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tmp = []
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for b in even:
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tmp.extend(self._manchester_lookup[b])
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length_even_IQ = 32*length_even
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IQ[pos:pos+length_even_IQ] = tmp
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pos += length_even_IQ
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ppm.extend(self.adsb_frame_pause) # pause
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pos += self._len_pause_IQ
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IQ[pos:pos+self._len_pre_IQ] = self._adsb_frame_preamble_IQ
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pos += self._len_pre_IQ
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tmp = []
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for b in odd:
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tmp.extend(self._manchester_lookup[b])
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IQ[pos:pos+32*length_odd] = tmp
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return bytearray(ppm)
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return IQ
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def hackrf_raw_IQ_format(self, ppm):
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"""
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Args:
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ppm: this is some data in ppm (pulse position modulation) which will be converted into
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hackRF raw IQ sample format, ready to be broadcasted
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Returns:
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bytearray: containing the IQ data
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"""
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signal = []
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bits = numpy.unpackbits(numpy.asarray(ppm, dtype=numpy.uint8))
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for bit in bits:
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if bit == 1:
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I = 127
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Q = 127
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else:
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I = 0
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Q = 0
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signal.append(I)
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signal.append(Q)
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else:
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return bytearray(signal)
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return None
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