add cqpsk-demod-file.py
git-svn-id: http://op25.osmocom.org/svn/trunk@219 65a5c917-d112-43f1-993d-58c26a4786be
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#!/usr/bin/env python
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#
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# (C) Copyright 2010 KA1RBI
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#
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# apply CQPSK demodulator and P25 decoder to a sample capture file.
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#
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# input file is a sampled complex signal, default rate=96k
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#
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# Example usage:
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# cqpsk-demod-file.py -i samples/trunk-control-complex-96KSS.dat -c 25300 -g 22
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#
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# FIXME: many of the blocks in this program should be moved to a hier block
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#
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import sys
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import os
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import math
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from gnuradio import gr, gru, audio, eng_notation, repeater
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from gnuradio.eng_option import eng_option
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from optparse import OptionParser
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from math import pi
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class my_top_block(gr.top_block):
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def __init__(self):
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gr.top_block.__init__(self)
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parser = OptionParser(option_class=eng_option)
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parser.add_option("-1", "--one-channel", action="store_true", default=False, help="software synthesized Q channel")
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parser.add_option("-c", "--calibration", type="eng_float", default=0, help="freq offset")
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parser.add_option("-d", "--debug", action="store_true", default=False, help="allow time at init to attach gdb")
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parser.add_option("-C", "--costas-alpha", type="eng_float", default=0.125, help="Costas alpha")
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parser.add_option("-g", "--gain", type="eng_float", default=1.0)
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parser.add_option("-i", "--input-file", type="string", default="in.dat", help="specify the input file")
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parser.add_option("-I", "--imbe", action="store_true", default=False, help="output IMBE codewords")
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parser.add_option("-L", "--low-pass", type="eng_float", default=12.5e3, help="low pass cut-off", metavar="Hz")
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parser.add_option("-o", "--output-file", type="string", default="out.dat", help="specify the output file")
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parser.add_option("-p", "--polarity", action="store_true", default=False, help="use reversed polarity")
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parser.add_option("-s", "--sample-rate", type="int", default=96000, help="input sample rate")
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parser.add_option("-v", "--verbose", action="store_true", default=False, help="additional output")
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(options, args) = parser.parse_args()
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sample_rate = options.sample_rate
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symbol_rate = 4800
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samples_per_symbol = sample_rate // symbol_rate
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IN = gr.file_source(gr.sizeof_gr_complex, options.input_file)
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if options.one_channel:
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C2F = gr.complex_to_float()
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F2C = gr.float_to_complex()
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# osc./mixer for mixing signal down to approx. zero IF
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LO = gr.sig_source_c (sample_rate, gr.GR_COS_WAVE, options.calibration, 1.0, 0)
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MIXER = gr.multiply_cc()
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# get signal into normalized range (-1.0 - +1.0)
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# FIXME: add AGC
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AMP = gr.multiply_const_cc(options.gain)
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lpf_taps = gr.firdes.low_pass(1.0, sample_rate, options.low_pass, options.low_pass * 0.1, gr.firdes.WIN_HANN)
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# decim by 2 to get 48k rate
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DECIM = gr.fir_filter_ccf (2, lpf_taps)
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sample_rate /= 2 # for DECIM
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samples_per_symbol /= 2 # for DECIM
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# create Gardner/Costas loop
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# the loop will not work if the sample levels aren't normalized (above)
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timing_error_gain = 0.025 # loop error gain
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gain_omega = 0.25 * timing_error_gain * timing_error_gain
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alpha = options.costas_alpha
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beta = 0.125 * alpha * alpha
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fmin = -0.025 # fmin and fmax are in radians/s
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fmax = 0.025
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GARDNER_COSTAS = repeater.gardner_costas_cc(samples_per_symbol, timing_error_gain, gain_omega, alpha, beta, fmax, fmin)
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# probably too much phase noise etc to attempt coherent demodulation
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# so we use differential
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DIFF = gr.diff_phasor_cc()
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# take angle of the phase difference (in radians)
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TOFLOAT = gr.complex_to_arg()
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# convert from radians such that signal is in [-3, -1, +1, +3]
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RESCALE = gr.multiply_const_ff(1 / (pi / 4.0))
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# optional polarity reversal (should be unnec. - now autodetected)
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p = 1.0
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if options.polarity:
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p = -1.0
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POLARITY = gr.multiply_const_ff(p)
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# hard decision at specified points
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levels = [-2.0, 0.0, 2.0, 4.0 ]
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SLICER = repeater.fsk4_slicer_fb(levels)
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# assemble received frames and route to Wireshark via UDP
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hostname = "127.0.0.1"
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port = 23456
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debug = 0
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if options.verbose:
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debug = 255
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do_imbe = False
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if options.imbe:
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do_imbe = True
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do_output = True # enable block's output stream
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do_msgq = False # msgq output not yet implemented
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msgq = gr.msg_queue(2)
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DECODER = repeater.p25_frame_assembler(hostname, port, debug, do_imbe, do_output, do_msgq, msgq)
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OUT = gr.file_sink(gr.sizeof_char, options.output_file)
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if options.one_channel:
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self.connect(IN, C2F, F2C, (MIXER, 0))
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else:
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self.connect(IN, (MIXER, 0))
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self.connect(LO, (MIXER, 1))
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self.connect(MIXER, AMP, DECIM, GARDNER_COSTAS, DIFF, TOFLOAT, RESCALE, POLARITY, SLICER, DECODER, OUT)
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if options.debug:
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print 'Ready for GDB to attach (pid = %d)' % (os.getpid(),)
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raw_input("Press 'Enter' to continue...")
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if __name__ == "__main__":
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try:
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my_top_block().run()
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except KeyboardInterrupt:
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tb.stop()
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