1 | # |
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2 | # Copyright 2005,2006 Free Software Foundation, Inc. |
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3 | # |
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4 | # This file is part of GNU Radio |
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5 | # |
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6 | # GNU Radio is free software; you can redistribute it and/or modify |
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7 | # it under the terms of the GNU General Public License as published by |
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8 | # the Free Software Foundation; either version 3, or (at your option) |
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9 | # any later version. |
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10 | # |
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11 | # GNU Radio is distributed in the hope that it will be useful, |
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12 | # but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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14 | # GNU General Public License for more details. |
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15 | # |
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16 | # You should have received a copy of the GNU General Public License |
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17 | # along with GNU Radio; see the file COPYING. If not, write to |
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18 | # the Free Software Foundation, Inc., 51 Franklin Street, |
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19 | # Boston, MA 02110-1301, USA. |
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20 | # |
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21 | |
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22 | from gnuradio import eng_notation |
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23 | |
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24 | _default_bitrate = 500e3 |
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25 | |
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26 | _valid_samples_per_symbol = (2,3,4,5,6,7) |
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27 | |
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28 | def _gen_tx_info(converter_rate): |
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29 | results = [] |
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30 | for samples_per_symbol in _valid_samples_per_symbol: |
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31 | for interp in range(16, 512 + 1, 4): |
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32 | bitrate = converter_rate / interp / samples_per_symbol |
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33 | results.append((bitrate, samples_per_symbol, interp)) |
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34 | results.sort() |
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35 | return results |
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36 | |
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37 | def _gen_rx_info(converter_rate): |
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38 | results = [] |
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39 | for samples_per_symbol in _valid_samples_per_symbol: |
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40 | for decim in range(8, 256 + 1, 2): |
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41 | bitrate = converter_rate / decim / samples_per_symbol |
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42 | results.append((bitrate, samples_per_symbol, decim)) |
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43 | results.sort() |
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44 | return results |
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45 | |
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46 | def _filter_info(info, samples_per_symbol, xrate): |
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47 | if samples_per_symbol is not None: |
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48 | info = [x for x in info if x[1] == samples_per_symbol] |
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49 | if xrate is not None: |
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50 | info = [x for x in info if x[2] == xrate] |
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51 | return info |
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52 | |
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53 | def _pick_best(target_bitrate, bits_per_symbol, info): |
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54 | """ |
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55 | @returns tuple (bitrate, samples_per_symbol, interp_rate_or_decim_rate) |
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56 | """ |
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57 | if len(info) == 0: |
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58 | raise RuntimeError, "info is zero length!" |
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59 | |
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60 | if target_bitrate is None: # return the fastest one |
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61 | return info[-1] |
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62 | |
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63 | # convert bit rate to symbol rate |
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64 | target_symbolrate = target_bitrate / bits_per_symbol |
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65 | |
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66 | # Find the closest matching symbol rate. |
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67 | # In the event of a tie, the one with the lowest samples_per_symbol wins. |
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68 | # (We already sorted them, so the first one is the one we take) |
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69 | |
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70 | best = info[0] |
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71 | best_delta = abs(target_symbolrate - best[0]) |
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72 | for x in info[1:]: |
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73 | delta = abs(target_symbolrate - x[0]) |
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74 | if delta < best_delta: |
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75 | best_delta = delta |
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76 | best = x |
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77 | |
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78 | # convert symbol rate back to bit rate |
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79 | return ((best[0] * bits_per_symbol),) + best[1:] |
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80 | |
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81 | def _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol, |
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82 | xrate, converter_rate, gen_info): |
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83 | """ |
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84 | @returns tuple (bitrate, samples_per_symbol, interp_rate_or_decim_rate) |
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85 | """ |
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86 | if not isinstance(bits_per_symbol, int) or bits_per_symbol < 1: |
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87 | raise ValueError, "bits_per_symbol must be an int >= 1" |
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88 | |
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89 | if samples_per_symbol is not None and xrate is not None: # completely determined |
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90 | return (float(converter_rate) / xrate / samples_per_symbol, |
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91 | samples_per_symbol, xrate) |
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92 | |
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93 | if bitrate is None and samples_per_symbol is None and xrate is None: |
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94 | bitrate = _default_bitrate |
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95 | |
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96 | # now we have a target bitrate and possibly an xrate or |
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97 | # samples_per_symbol constraint, but not both of them. |
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98 | |
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99 | ret = _pick_best(bitrate, bits_per_symbol, |
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100 | _filter_info(gen_info(converter_rate), samples_per_symbol, xrate)) |
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101 | print "Actual Bitrate:", eng_notation.num_to_str(ret[0]) |
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102 | return ret |
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103 | |
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104 | # --------------------------------------------------------------------------------------- |
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105 | |
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106 | def pick_tx_bitrate(bitrate, bits_per_symbol, samples_per_symbol, |
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107 | interp_rate, converter_rate): |
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108 | """ |
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109 | Given the 4 input parameters, return at configuration that matches |
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110 | |
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111 | @param bitrate: desired bitrate or None |
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112 | @type bitrate: number or None |
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113 | @param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3 |
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114 | @type bits_per_symbol: integer >= 1 |
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115 | @param samples_per_symbol: samples/baud (aka samples/symbol) |
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116 | @type samples_per_symbol: number or None |
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117 | @param interp_rate: USRP interpolation factor |
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118 | @type interp_rate: integer or None |
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119 | @param converter_rate: converter sample rate in Hz |
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120 | @type converter_rate: number |
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121 | |
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122 | @returns tuple (bitrate, samples_per_symbol, interp_rate) |
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123 | """ |
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124 | print "Requested TX Bitrate:", bitrate and eng_notation.num_to_str(bitrate) or 'Auto' |
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125 | return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol, |
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126 | interp_rate, converter_rate, _gen_tx_info) |
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127 | |
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128 | |
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129 | def pick_rx_bitrate(bitrate, bits_per_symbol, samples_per_symbol, |
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130 | decim_rate, converter_rate): |
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131 | """ |
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132 | Given the 4 input parameters, return at configuration that matches |
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133 | |
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134 | @param bitrate: desired bitrate or None |
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135 | @type bitrate: number or None |
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136 | @param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3 |
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137 | @type bits_per_symbol: integer >= 1 |
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138 | @param samples_per_symbol: samples/baud (aka samples/symbol) |
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139 | @type samples_per_symbol: number or None |
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140 | @param decim_rate: USRP decimation factor |
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141 | @type decim_rate: integer or None |
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142 | @param converter_rate: converter sample rate in Hz |
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143 | @type converter_rate: number |
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144 | |
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145 | @returns tuple (bitrate, samples_per_symbol, decim_rate) |
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146 | """ |
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147 | print "Requested RX Bitrate:", bitrate and eng_notation.num_to_str(bitrate) or 'Auto' |
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148 | return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol, |
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149 | decim_rate, converter_rate, _gen_rx_info) |
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