| #!/usr/bin/env python2 |
| # -*- coding: utf-8 -*- |
| # @file |
| # @author (C) 2014 by Piotr Krysik <ptrkrysik@gmail.com> |
| # @section LICENSE |
| # |
| # Gr-gsm 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, or (at your option) |
| # any later version. |
| # |
| # Gr-gsm 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 gr-gsm; see the file COPYING. If not, write to |
| # the Free Software Foundation, Inc., 51 Franklin Street, |
| # Boston, MA 02110-1301, USA. |
| # |
| |
| ################################################## |
| # Gnuradio Python Flow Graph |
| # Title: FCCH Bursts Detector |
| # Author: Piotr Krysik |
| # |
| # Description: Detects positions of FCCH bursts. At the end of each |
| # detected FCCH burst adds to the stream a tag with key "fcch" and value |
| # which is a frequency offset estimate. The input sampling frequency |
| # should be integer multiply of GSM GMKS symbol rate - 1625000/6 Hz. |
| ################################################## |
| |
| from gnuradio import blocks |
| from gnuradio import gr |
| from gnuradio.filter import firdes |
| import grgsm |
| |
| class fcch_detector(gr.hier_block2): |
| |
| def __init__(self, OSR=4): |
| gr.hier_block2.__init__( |
| self, "FCCH bursts detector", |
| gr.io_signature(1, 1, gr.sizeof_gr_complex*1), |
| gr.io_signature(1, 1, gr.sizeof_gr_complex*1), |
| ) |
| |
| ################################################## |
| # Parameters |
| ################################################## |
| self.OSR = OSR |
| |
| ################################################## |
| # Variables |
| ################################################## |
| self.f_symb = f_symb = 1625000.0/6.0 |
| self.samp_rate = samp_rate = f_symb*OSR |
| |
| ################################################## |
| # Blocks |
| ################################################## |
| self.gsm_fcch_burst_tagger_0 = grgsm.fcch_burst_tagger(OSR) |
| self.blocks_threshold_ff_0_0 = blocks.threshold_ff(0, 0, 0) |
| self.blocks_threshold_ff_0 = blocks.threshold_ff(int((138)*samp_rate/f_symb), int((138)*samp_rate/f_symb), 0) |
| self.blocks_multiply_conjugate_cc_0 = blocks.multiply_conjugate_cc(1) |
| self.blocks_moving_average_xx_0 = blocks.moving_average_ff(int((142)*samp_rate/f_symb), 1, int(1e6)) |
| self.blocks_delay_0 = blocks.delay(gr.sizeof_gr_complex*1, int(OSR)) |
| self.blocks_complex_to_arg_0 = blocks.complex_to_arg(1) |
| |
| ################################################## |
| # Connections |
| ################################################## |
| self.connect((self, 0), (self.blocks_multiply_conjugate_cc_0, 0)) |
| self.connect((self.blocks_delay_0, 0), (self.blocks_multiply_conjugate_cc_0, 1)) |
| self.connect((self.blocks_complex_to_arg_0, 0), (self.blocks_threshold_ff_0_0, 0)) |
| self.connect((self, 0), (self.blocks_delay_0, 0)) |
| self.connect((self.blocks_multiply_conjugate_cc_0, 0), (self.blocks_complex_to_arg_0, 0)) |
| self.connect((self.blocks_moving_average_xx_0, 0), (self.blocks_threshold_ff_0, 0)) |
| self.connect((self.blocks_threshold_ff_0_0, 0), (self.blocks_moving_average_xx_0, 0)) |
| self.connect((self.gsm_fcch_burst_tagger_0, 0), (self, 0)) |
| self.connect((self, 0), (self.gsm_fcch_burst_tagger_0, 0)) |
| self.connect((self.blocks_threshold_ff_0, 0), (self.gsm_fcch_burst_tagger_0, 1)) |
| |
| def get_OSR(self): |
| return self.OSR |
| |
| def set_OSR(self, OSR): |
| self.OSR = OSR |
| self.set_samp_rate(self.f_symb*self.OSR) |
| self.blocks_delay_0.set_dly(int(self.OSR)) |
| |
| |