3 # Copyright 2005,2006 Free Software Foundation, Inc.
5 # This file is part of GNU Radio
7 # GNU Radio is free software; you can redistribute it and/or modify
8 # it under the terms of the GNU General Public License as published by
9 # the Free Software Foundation; either version 2, or (at your option)
12 # GNU Radio is distributed in the hope that it will be useful,
13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 # GNU General Public License for more details.
17 # You should have received a copy of the GNU General Public License
18 # along with GNU Radio; see the file COPYING. If not, write to
19 # the Free Software Foundation, Inc., 51 Franklin Street,
20 # Boston, MA 02110-1301, USA.
23 _default_bitrate = 500e3
25 _valid_samples_per_symbol = (2,3,4,5,6,7)
27 def _gen_tx_info(converter_rate):
29 for samples_per_symbol in _valid_samples_per_symbol:
30 for interp in range(16, 512 + 1, 4):
31 bitrate = converter_rate / interp / samples_per_symbol
32 results.append((bitrate, samples_per_symbol, interp))
36 def _gen_rx_info(converter_rate):
38 for samples_per_symbol in _valid_samples_per_symbol:
39 for decim in range(8, 256 + 1, 2):
40 bitrate = converter_rate / decim / samples_per_symbol
41 results.append((bitrate, samples_per_symbol, decim))
45 def _filter_info(info, samples_per_symbol, xrate):
46 if samples_per_symbol is not None:
47 info = [x for x in info if x[1] == samples_per_symbol]
49 info = [x for x in info if x[2] == xrate]
52 def _pick_best(target_bitrate, bits_per_symbol, info):
54 @returns tuple (bitrate, samples_per_symbol, interp_rate_or_decim_rate)
57 raise RuntimeError, "info is zero length!"
59 if target_bitrate is None: # return the fastest one
62 # convert bit rate to symbol rate
63 target_symbolrate = target_bitrate / bits_per_symbol
65 # Find the closest matching symbol rate.
66 # In the event of a tie, the one with the lowest samples_per_symbol wins.
67 # (We already sorted them, so the first one is the one we take)
70 best_delta = abs(target_symbolrate - best[0])
72 delta = abs(target_symbolrate - x[0])
73 if delta < best_delta:
77 # convert symbol rate back to bit rate
78 return ((best[0] * bits_per_symbol),) + best[1:]
80 def _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
81 xrate, converter_rate, gen_info):
83 @returns tuple (bitrate, samples_per_symbol, interp_rate_or_decim_rate)
85 if not isinstance(bits_per_symbol, int) or bits_per_symbol < 1:
86 raise ValueError, "bits_per_symbol must be an int >= 1"
88 if samples_per_symbol is not None and xrate is not None: # completely determined
89 return (float(converter_rate) / xrate / samples_per_symbol,
90 samples_per_symbol, xrate)
92 if bitrate is None and samples_per_symbol is None and xrate is None:
93 bitrate = _default_bitrate
95 # now we have a target bitrate and possibly an xrate or
96 # samples_per_symbol constraint, but not both of them.
98 return _pick_best(bitrate, bits_per_symbol,
99 _filter_info(gen_info(converter_rate), samples_per_symbol, xrate))
101 # ---------------------------------------------------------------------------------------
103 def pick_tx_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
104 interp_rate, converter_rate=128e6):
106 Given the 4 input parameters, return at configuration that matches
108 @param bitrate: desired bitrate or None
109 @type bitrate: number or None
110 @param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3
111 @type bits_per_symbol: integer >= 1
112 @param samples_per_symbol: samples/baud (aka samples/symbol)
113 @type samples_per_symbol: number or None
114 @param interp_rate: USRP interpolation factor
115 @type interp_rate: integer or None
116 @param converter_rate: converter sample rate in Hz
117 @type converter_rate: number
119 @returns tuple (bitrate, samples_per_symbol, interp_rate)
121 return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
122 interp_rate, converter_rate, _gen_tx_info)
125 def pick_rx_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
126 decim_rate, converter_rate=64e6):
128 Given the 4 input parameters, return at configuration that matches
130 @param bitrate: desired bitrate or None
131 @type bitrate: number or None
132 @param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3
133 @type bits_per_symbol: integer >= 1
134 @param samples_per_symbol: samples/baud (aka samples/symbol)
135 @type samples_per_symbol: number or None
136 @param decim_rate: USRP decimation factor
137 @type decim_rate: integer or None
138 @param converter_rate: converter sample rate in Hz
139 @type converter_rate: number
141 @returns tuple (bitrate, samples_per_symbol, decim_rate)
143 return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
144 decim_rate, converter_rate, _gen_rx_info)