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op25-legacy/python/usrp2_c4fm_rx_nogui.py

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#!/usr/bin/env python
# -*- mode: Python -*-
# Copyright 2011 Steve Glass
#
# This file is part of OP25.
#
# OP25 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.
#
# OP25 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 OP25; see the file COPYING. If not, write to the Free
# Software Foundation, Inc., 51 Franklin Street, Boston, MA
# 02110-1301, USA.
import math
import os
import sys
import threading
from gnuradio import audio, gr, gru, op25, usrp2
from gnuradio.eng_option import eng_option
from math import pi
# The P25 receiver
#
class usrp2_c4fm_rx (gr.top_block):
# Initialize the P25 receiver
#
def __init__(self, interface, address, center_freq, offset_freq, decim, squelch, gain):
gr.top_block.__init__(self)
# setup USRP2
u = usrp2.source_32fc(interface, address)
u.set_decim(decim)
capture_rate = u.adc_rate() / decim
u.set_center_freq(center_freq)
if gain is None:
g = u.gain_range()
gain = float(g[0] + g[1]) / 2
u.set_gain(gain)
# Setup receiver attributes
channel_rate = 125000
symbol_rate = 4800
# channel filter
self.channel_offset = offset_freq
channel_decim = capture_rate // channel_rate
channel_rate = capture_rate // channel_decim
trans_width = 12.5e3 / 2;
trans_centre = trans_width + (trans_width / 2)
coeffs = gr.firdes.low_pass(1.0, capture_rate, trans_centre, trans_width, gr.firdes.WIN_HANN)
self.channel_filter = gr.freq_xlating_fir_filter_ccf(channel_decim, coeffs, self.channel_offset, capture_rate)
self.connect(u, self.channel_filter)
# power squelch
power_squelch = gr.pwr_squelch_cc(squelch, 1e-3, 0, True)
self.connect(self.channel_filter, power_squelch)
# FM demodulator
self.symbol_deviation = 600.0
fm_demod_gain = channel_rate / (2.0 * pi * self.symbol_deviation)
fm_demod = gr.quadrature_demod_cf(fm_demod_gain)
self.connect(power_squelch, fm_demod)
# symbol filter
symbol_decim = 1
samples_per_symbol = channel_rate // symbol_rate
symbol_coeffs = (1.0/samples_per_symbol,) * samples_per_symbol
symbol_filter = gr.fir_filter_fff(symbol_decim, symbol_coeffs)
self.connect(fm_demod, symbol_filter)
# C4FM demodulator
autotuneq = gr.msg_queue(2)
self.demod_watcher = demod_watcher(autotuneq, self.adjust_channel_offset)
demod_fsk4 = op25.fsk4_demod_ff(autotuneq, channel_rate, symbol_rate)
self.connect(symbol_filter, demod_fsk4)
# symbol slicer
levels = [ -2.0, 0.0, 2.0, 4.0 ]
slicer = op25.fsk4_slicer_fb(levels)
self.connect(demod_fsk4, slicer)
# frame decoder
decoder = op25.decoder_bf()
self.connect(slicer, decoder)
# try to connect audio output device
try:
audio_sink = audio.sink(8000, "plughw:0,0", True)
self.connect(decoder, audio_sink)
except Exception:
sink = gr.null_sink(gr.sizeof_float)
self.connect(decoder, null);
# Adjust the channel offset
#
def adjust_channel_offset(self, delta_hz):
max_delta_hz = 12000.0
delta_hz *= self.symbol_deviation
delta_hz = max(delta_hz, -max_delta_hz)
delta_hz = min(delta_hz, max_delta_hz)
self.channel_filter.set_center_freq(self.channel_offset - delta_hz)
# Demodulator frequency tracker
#
class demod_watcher(threading.Thread):
def __init__(self, msgq, callback, **kwds):
threading.Thread.__init__ (self, **kwds)
self.setDaemon(1)
self.msgq = msgq
self.callback = callback
self.keep_running = True
self.start()
def run(self):
while(self.keep_running):
msg = self.msgq.delete_head()
frequency_correction = msg.arg1()
self.callback(frequency_correction)
# Run the receiver
#
if '__main__' == __name__:
from optparse import OptionParser
parser = OptionParser(option_class=eng_option)
parser.add_option("-i", "--interface", type="string", default="eth0",
help="select Ethernet interface, default is eth0")
parser.add_option("-a", "--address", type="string", default="",
help="select USRP by MAC address, default is auto-select")
parser.add_option("-f", "--freq", type="eng_float", default=434.075e6,
help="rx frequency [=%default]", metavar="Hz")
parser.add_option("-c", "--calibration", type="eng_float", default=0.0,
help="frequency offset [=%default]", metavar="Hz")
parser.add_option("-d", "--decim", type="int", default=400,
help="decimation factor [=%default]")
parser.add_option("-s", "--squelch", type="eng_float", default=15.0,
help="squelch threshold [=%default]", metavar="dB")
parser.add_option("-g", "--gain", type="eng_float", default=None, help="gain", metavar="dB")
(options, args) = parser.parse_args()
if len(args) != 0:
parser.print_help()
sys.exit(1)
self.options = options
try:
rx = usrp2_c4fm_rx(options.interface, options.address, options.freq, options.calibration, options.decim, options.squelch, options.gain)
rx.run()
except KeyboardInterrupt:
pass