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#!/usr/bin/env python
#
# Copyright 2007 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 3, 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., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
from gnuradio import gr, usrp, eng_notation
n2s = eng_notation.num_to_str
# Hierarchical block implementing a USRP source for complex floats,
# with convenience functions for gain, tune, decimation, etc.
#
class usrp_source_c(gr.hier_block2):
"""
Create a USRP source object supplying complex floats.
"""
def __init__(self, which=0, subdev_spec=None, gain=None, if_rate=None,
freq=0.0, calibration=0.0, verbose=False):
# Call hierarchical block constructor
gr.hier_block2.__init__(self,
"usrp_source_c", # Block typename
gr.io_signature(0,0,0), # Input signature
gr.io_signature(1,1,gr.sizeof_gr_complex)) # Output signature
self._verbose = verbose
self._u = usrp.source_c(which)
if self._verbose:
print 'ADC sample rate is', n2s(self._u.adc_rate()), "sps"
self.set_subdev(subdev_spec)
self.set_if_rate(if_rate)
self.set_gain(gain)
self.set_calibration(calibration)
self.tune(freq)
self.connect(self._u, self)
def set_subdev(self, subdev_spec):
if subdev_spec is None:
subdev_spec = self.pick_subdevice()
self._subdev = usrp.selected_subdev(self._u, subdev_spec)
self._u.set_mux(usrp.determine_rx_mux_value(self._u, subdev_spec))
if self._verbose:
print 'RX using', self._subdev.name(), 'daughterboard'
def pick_subdevice(self):
"""
The user didn't specify a subdevice.
If there's a daughterboard on A, select A.
If there's a daughterboard on B, select B.
Otherwise, select A.
"""
if self._u.db(0, 0).dbid() >= 0: # dbid is < 0 if there's no d'board or a problem
return (0, 0)
if self._u.db(1, 0).dbid() >= 0:
return (1, 0)
return (0, 0)
def set_if_rate(self, if_rate):
# If no IF rate specified, set to maximum decimation
if if_rate is None:
self._decim = 256
else:
self._decim = int(self._u.adc_rate()/if_rate)
self._u.set_decim_rate(self._decim)
self._if_rate = self._u.adc_rate()/self._decim
if self._verbose:
print "USRP decimation rate is", self._decim
print "USRP IF rate is", n2s(self._if_rate), "sps"
def set_gain(self, gain):
# If no gain specified, set to midrange
if gain is None:
g = self._subdev.gain_range()
gain = (g[0]+g[1])/2.0
self._gain = gain
self._subdev.set_gain(self._gain)
def set_calibration(self, calibration):
self._cal = calibration
if self._verbose:
print "Using frequency calibration offset of", n2s(calibration), "Hz"
def tune(self, freq):
"""
Set the center frequency we're interested in.
@param target_freq: frequency in Hz
@type: 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 down converter.
"""
self._tune_result = usrp.tune(self._u, 0, self._subdev, freq+self._cal)
if self._tune_result:
if self._verbose:
print "Baseband frequency is", n2s(self._tune_result.baseband_freq), "Hz"
print "DXC frequency is", n2s(self._tune_result.dxc_freq), "Hz"
print "Center frequency is", n2s(freq), "Hz"
print "Residual frequency is", n2s(self._tune_result.residual_freq), "Hz"
return True
return False
if __name__ == '__main__':
src = usrp_source_c(verbose=True)
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