120 lines
3.8 KiB
Python
Executable File
120 lines
3.8 KiB
Python
Executable File
#! /usr/bin/python
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# P25 TDMA Decoder (C) Copyright 2013 KA1RBI
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#
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# This file is part of OP25
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#
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# OP25 is free software; you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3, or (at your option)
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# any later version.
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#
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# OP25 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
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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# License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with OP25; see the file COPYING. If not, write to the Free
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# Software Foundation, Inc., 51 Franklin Street, Boston, MA
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# 02110-1301, USA.
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"""
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Decode a file of P25 TDMA symbols and write out all detected voice codewords
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After FEC decoding, print the resulting "B" vectors (49 bits per CW).
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Optionally, dump the timeslot info (type, position, type of content)
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The input file must contain the demodulated symbols, one per character
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using the low-order two bits of each byte
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"""
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import sys
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import numpy as np
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from optparse import OptionParser
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from bit_utils import *
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import isch
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import duid
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import lfsr
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from vf import process_v
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SUPERFRAME_LEN = 2160
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def main():
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parser = OptionParser()
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parser.add_option("-v", "--verbose", action="store_true", default=False)
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parser.add_option("-i", "--input-file", type="string", default=None, help="input file name")
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parser.add_option("-n", "--nac", type="int", default=0, help="NAC")
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parser.add_option("-s", "--sysid", type="int", default=0, help="sysid")
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parser.add_option("-w", "--wacn", type="int", default=0, help="WACN")
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(options, args) = parser.parse_args()
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if len(args) != 0:
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parser.print_help()
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sys.exit(1)
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file = options.input_file
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my_isch = isch.p25p2_isch()
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my_duid = duid.p25p2_duid()
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my_lfsr = lfsr.p25p2_lfsr(options.nac, options.sysid, options.wacn)
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#print 'nac: %d' % options.nac
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d = open(file).read()
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symbols = []
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for c in d:
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symbols.append(ord(c))
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sync0= bits_to_dibits(mk_array(0x575d57f7ff,40))
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sync_start = find_sym(sync0, symbols)
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assert sync_start > 0 # unable to locate any sync sequence
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superframe = -1
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for i in xrange(sync_start, sync_start + (180*32), 180):
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chn, loc, fr, cnt = my_isch.decode_isch ( symbols [ i : i + 20 ])
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if chn == 0 and loc == 0:
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superframe = i
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break
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assert superframe > 0 # unable to locate start of superframe
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errors = 0
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for i in xrange(superframe,len(symbols)-SUPERFRAME_LEN,SUPERFRAME_LEN):
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syms1 = symbols[i + 10: i + SUPERFRAME_LEN + 10]
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syms2 = np.array(syms1) ^ my_lfsr.xorsyms
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for j in xrange(12):
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if options.verbose:
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print '%s superframe %d timeslot %d %s' % ('=' * 20, i, j, '=' * 20)
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chn, loc, fr, cnt = my_isch.decode_isch ( symbols [ i + (j*180) : i + (j*180) + 20 ])
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if chn == -1:
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if options.verbose:
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print 'unknown isch codeword at %d' % (i + (j*180))
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errors += 1
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elif chn == -2:
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if options.verbose:
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print 'sync isch codeword found at %d' % (i + (j*180))
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errors = 0
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else:
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if options.verbose:
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print "channel %d loc %d fr %d count %d" % (chn, loc, fr, cnt)
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errors = 0
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burst = syms1 [ (j*180) : (j*180) + 180 ]
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burst_d= syms2 [ (j*180) : (j*180) + 180 ]
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btype = my_duid.decode_duid(burst)
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if options.verbose:
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print 'burst at %d type %s' % (i + (j*180), btype)
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if btype == '2v' or btype == '4v':
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process_v(burst_d, btype)
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elif not btype.startswith('unknown'):
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maybe_sync = burst[79:79+21]
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if btype.endswith(' w'): # scrambled
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burst = burst_d
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# process_oemi(burst, btype)
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if errors > 6:
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if options.verbose:
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print "too many successive errors, exiting at i=%d" % (i)
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break
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if __name__ == "__main__":
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main()
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