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#
# Copyright 2010 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 eng_notation
_default_bitrate = 500e3
_sps_min = 2
_sps_max = 100
def _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
xrate, converter_rate, xrates):
"""
@returns tuple (bitrate, samples_per_symbol, interp_rate_or_decim_rate)
"""
if not isinstance(bits_per_symbol, int) or bits_per_symbol < 1:
raise ValueError, "bits_per_symbol must be an int >= 1"
converter_rate = float(converter_rate)
bits_per_symbol = float(bits_per_symbol)
# completely determined; if bitrate is specified, this overwrites it
if (samples_per_symbol is not None) and (xrate is not None):
bitrate = converter_rate / bits_per_symbol / xrate / samples_per_symbol
# If only SPS is given
if (bitrate is None) and (samples_per_symbol is not None) and (xrate is None):
xrate = max(xrates)
bitrate = converter_rate / bits_per_symbol / xrate / samples_per_symbol
# If only xrate is given, just set SPS to 2 and calculate bitrate
if (bitrate is None) and (samples_per_symbol is None) and (xrate is not None):
samples_per_symbol = 2.0
bitrate = converter_rate / bits_per_symbol / xrate / samples_per_symbol
# If no parameters are give, use the default bit rate
if (bitrate is None) and (samples_per_symbol is None) and (xrate is None):
bitrate = _default_bitrate
# If only bitrate is specified, return max xrate and appropriate
# samples per symbol (minimum of 2.0) to reach bit rate
if (samples_per_symbol is None) and (xrate is None):
xrates.sort()
for i in xrange(len(xrates)):
if((converter_rate / bits_per_symbol / xrates[i]) >= 2*bitrate):
rate = xrates[i]
else:
break
try:
xrate = rate
except UnboundLocalError:
raise ValueError("Requested bitrate out of bounds")
samples_per_symbol = converter_rate / bits_per_symbol / rate / bitrate
bitrate = converter_rate / bits_per_symbol / xrate / samples_per_symbol
# If bitrate and xrate are specified
if(samples_per_symbol is None):
samples_per_symbol = converter_rate / xrate / bits_per_symbol / bitrate
# If bitrate and SPS are specified
if(xrate is None):
xrate = converter_rate / samples_per_symbol / bits_per_symbol / bitrate
if((xrate in xrates) == False):
# Find the closest avaiable rate larger than the calculated one
xrates.sort()
for x in xrates:
if(x > xrate):
xrate = x
break
if(xrate > max(xrates)):
xrate = max(xrates)
bitrate = converter_rate / bits_per_symbol / xrate / samples_per_symbol
print "Could not find suitable rate for specified SPS and Bitrate"
print "Using rate = %d for bitrate of %sbps" % \
(xrate, (eng_notation.num_to_str(bitrate)))
if((xrate in xrates) == False):
raise ValueError(("Invalid rate (rate = %d)" % xrate))
if((samples_per_symbol < _sps_min) or (samples_per_symbol > _sps_max)):
raise ValueError(("Invalid samples per symbol (sps = %.2f). Must be in [%.0f, %.0f]." \
% (samples_per_symbol, _sps_min, _sps_max)))
return (bitrate, samples_per_symbol, int(xrate))
def pick_tx_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
interp_rate, converter_rate, possible_interps):
"""
Given the 4 input parameters, return at configuration that matches
@param bitrate: desired bitrate or None
@type bitrate: number or None
@param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3
@type bits_per_symbol: integer >= 1
@param samples_per_symbol: samples/baud (aka samples/symbol)
@type samples_per_symbol: number or None
@param interp_rate: USRP interpolation factor
@type interp_rate: integer or None
@param converter_rate: converter sample rate in Hz
@type converter_rate: number
@param possible_interps: a list of possible rates
@type possible_interps: a list of integers
@returns tuple (bitrate, samples_per_symbol, interp_rate)
"""
return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
interp_rate, converter_rate, possible_interps)
def pick_rx_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
decim_rate, converter_rate, possible_decims):
"""
Given the 4 input parameters, return at configuration that matches
@param bitrate: desired bitrate or None
@type bitrate: number or None
@param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3
@type bits_per_symbol: integer >= 1
@param samples_per_symbol: samples/baud (aka samples/symbol)
@type samples_per_symbol: number or None
@param decim_rate: USRP decimation factor
@type decim_rate: integer or None
@param converter_rate: converter sample rate in Hz
@type converter_rate: number
@param possible_decims: a list of possible rates
@type possible_decims: a list of integers
@returns tuple (bitrate, samples_per_symbol, decim_rate)
"""
return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
decim_rate, converter_rate, possible_decims)
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