+#
+# 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
-def pick_rx_bitrate(bitrate, bits_per_symbol,
- converter_rate, possible_decims):
+_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)
"""
- 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 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
+ if not isinstance(bits_per_symbol, int) or bits_per_symbol < 1:
+ raise ValueError, "bits_per_symbol must be an int >= 1"
- @returns tuple (bitrate, samples_per_symbol, decim_rate)
- """
+ 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
- rates = list(possible_decims)
- rates.sort()
+ # 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
- for i in xrange(len(rates)):
- if((converter_rate / float(bits_per_symbol) / rates[i]) >= 2*bitrate):
- decim = rates[i]
- else:
- break
+ # 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
- sps = converter_rate / float(bits_per_symbol) / decim / bitrate
- br = converter_rate / float(bits_per_symbol) / decim / sps
+ try:
+ xrate = rate
+ except UnboundLocalError:
+ print "Requested bitrate out of bounds"
+ sys.exit(1)
+
+ samples_per_symbol = converter_rate / bits_per_symbol / rate / bitrate
+ bitrate = converter_rate / bits_per_symbol / xrate / samples_per_symbol
- return (br, sps, int(decim))
+ # 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)))
-def pick_tx_bitrate(bitrate, bits_per_symbol,
- converter_rate, possible_interps):
+ 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]." \
+ % (xrate, _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
@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
@returns tuple (bitrate, samples_per_symbol, interp_rate)
"""
- rates = list(possible_interps)
- rates.sort()
+ 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
- for i in xrange(len(rates)):
- if((converter_rate / float(bits_per_symbol) / rates[i]) >= 2*bitrate):
- interp = rates[i]
- else:
- break
+ @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
- sps = converter_rate / float(bits_per_symbol) / interp / bitrate
- br = converter_rate / float(bits_per_symbol) / interp / sps
+ @returns tuple (bitrate, samples_per_symbol, decim_rate)
+ """
- return (br, sps, int(interp))
+ return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
+ decim_rate, converter_rate, possible_decims)
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