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#!/usr/bin/env python
#
# Copyright 2005,2006 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio 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 2, or (at your option)
# any later version.
#
# GNU Radio 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 GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.
#
from gnuradio import gr, gru, blks
from gnuradio import usrp
# from current dir
from pick_bitrate import pick_rx_bitrate
# /////////////////////////////////////////////////////////////////////////////
# receive path
# /////////////////////////////////////////////////////////////////////////////
class receive_path(gr.hier_block):
def __init__(self, fg, demod_class, rx_subdev_spec,
bitrate, decim, spb,
rx_callback, options, demod_kwargs):
self.u = usrp.source_c (fusb_block_size=options.fusb_block_size,
fusb_nblocks=options.fusb_nblocks)
adc_rate = self.u.adc_rate()
(self._bitrate, self._spb, self._decim) = \
pick_rx_bitrate(bitrate, demod_class.bits_per_baud(), spb, decim, adc_rate)
self.u.set_decim_rate(self._decim)
sw_decim = 1
if rx_subdev_spec is None:
rx_subdev_spec = usrp.pick_rx_subdevice(self.u)
self.subdev = usrp.selected_subdev(self.u, rx_subdev_spec)
print "Using RX d'board %s" % (self.subdev.side_and_name(),)
self.u.set_mux(usrp.determine_rx_mux_value(self.u, rx_subdev_spec))
# Create filter to get actual channel we want
chan_coeffs = gr.firdes.low_pass (1.0, # gain
sw_decim * self._spb, # sampling rate
1.0, # midpoint of trans. band
0.1, # width of trans. band
gr.firdes.WIN_HANN) # filter type
print "len(rx_chan_coeffs) =", len(chan_coeffs)
# Decimating Channel filter
# complex in and out, float taps
self.chan_filt = gr.fft_filter_ccc(sw_decim, chan_coeffs)
#self.chan_filt = gr.fir_filter_ccf(sw_decim, chan_coeffs)
# receiver
self.packet_receiver = \
blks.demod_pkts(fg,
demod_class(fg, spb=self._spb, **demod_kwargs),
access_code=None,
callback=rx_callback,
threshold=-1)
fg.connect(self.u, self.chan_filt, self.packet_receiver)
gr.hier_block.__init__(self, fg, None, None)
g = self.subdev.gain_range()
#self.set_gain((g[0] + g[1])/2) # set gain to midpoint
self.set_gain(g[1]) # set gain to max
self.set_auto_tr(True) # enable Auto Transmit/Receive switching
# Carrier Sensing Blocks
alpha = 0.001
thresh = 30 # in dB, will have to adjust
self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)
fg.connect(self.chan_filt, self.probe)
def set_freq(self, target_freq):
"""
Set the center frequency we're interested in.
@param target_freq: frequency in Hz
@rypte: bool
Tuning is a two step process. First we ask the front-end to
tune as close to the desired frequency as it can. Then we use
the result of that operation and our target_frequency to
determine the value for the digital up converter.
"""
r = self.u.tune(0, self.subdev, target_freq)
if r:
return True
return False
def set_gain(self, gain):
if gain is None:
r = self.subdev.gain_range()
gain = (r[0] + r[1])/2 # set gain to midpoint
self.gain = gain
return self.subdev.set_gain(gain)
def set_auto_tr(self, enable):
return self.subdev.set_auto_tr(enable)
def bitrate(self):
return self._bitrate
def spb(self):
return self._spb
def decim(self):
return self._decim
def carrier_sensed(self):
"""
Return True if we think carrier is present.
"""
#return self.probe.level() > X
return self.probe.unmuted()
def carrier_threshold(self):
"""
Return current setting in dB.
"""
return self.probe.threshold()
def set_carrier_threshold(self, threshold_in_db):
"""
Set carrier threshold.
@param threshold_in_db: set detection threshold
@type threshold_in_db: float (dB)
"""
self.probe.set_threshold(threshold_in_db)
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