2 # Copyright 2005,2006 Free Software Foundation, Inc.
4 # This file is part of GNU Radio
6 # GNU Radio is free software; you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation; either version 3, or (at your option)
11 # GNU Radio is distributed in the hope that it will be useful,
12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 # GNU General Public License for more details.
16 # You should have received a copy of the GNU General Public License
17 # along with GNU Radio; see the file COPYING. If not, write to
18 # the Free Software Foundation, Inc., 51 Franklin Street,
19 # Boston, MA 02110-1301, USA.
22 _default_bitrate = 500e3
24 _valid_samples_per_symbol = (2,3,4,5,6,7)
26 def _gen_tx_info(converter_rate):
28 for samples_per_symbol in _valid_samples_per_symbol:
29 for interp in range(16, 512 + 1, 4):
30 bitrate = converter_rate / interp / samples_per_symbol
31 results.append((bitrate, samples_per_symbol, interp))
35 def _gen_rx_info(converter_rate):
37 for samples_per_symbol in _valid_samples_per_symbol:
38 for decim in range(8, 256 + 1, 2):
39 bitrate = converter_rate / decim / samples_per_symbol
40 results.append((bitrate, samples_per_symbol, decim))
44 def _filter_info(info, samples_per_symbol, xrate):
45 if samples_per_symbol is not None:
46 info = [x for x in info if x[1] == samples_per_symbol]
48 info = [x for x in info if x[2] == xrate]
51 def _pick_best(target_bitrate, bits_per_symbol, info):
53 @returns tuple (bitrate, samples_per_symbol, interp_rate_or_decim_rate)
56 raise RuntimeError, "info is zero length!"
58 if target_bitrate is None: # return the fastest one
61 # convert bit rate to symbol rate
62 target_symbolrate = target_bitrate / bits_per_symbol
64 # Find the closest matching symbol rate.
65 # In the event of a tie, the one with the lowest samples_per_symbol wins.
66 # (We already sorted them, so the first one is the one we take)
69 best_delta = abs(target_symbolrate - best[0])
71 delta = abs(target_symbolrate - x[0])
72 if delta < best_delta:
76 # convert symbol rate back to bit rate
77 return ((best[0] * bits_per_symbol),) + best[1:]
79 def _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
80 xrate, converter_rate, gen_info):
82 @returns tuple (bitrate, samples_per_symbol, interp_rate_or_decim_rate)
84 if not isinstance(bits_per_symbol, int) or bits_per_symbol < 1:
85 raise ValueError, "bits_per_symbol must be an int >= 1"
87 if samples_per_symbol is not None and xrate is not None: # completely determined
88 return (float(converter_rate) / xrate / samples_per_symbol,
89 samples_per_symbol, xrate)
91 if bitrate is None and samples_per_symbol is None and xrate is None:
92 bitrate = _default_bitrate
94 # now we have a target bitrate and possibly an xrate or
95 # samples_per_symbol constraint, but not both of them.
97 return _pick_best(bitrate, bits_per_symbol,
98 _filter_info(gen_info(converter_rate), samples_per_symbol, xrate))
100 # ---------------------------------------------------------------------------------------
102 def pick_tx_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
103 interp_rate, converter_rate=128e6):
105 Given the 4 input parameters, return at configuration that matches
107 @param bitrate: desired bitrate or None
108 @type bitrate: number or None
109 @param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3
110 @type bits_per_symbol: integer >= 1
111 @param samples_per_symbol: samples/baud (aka samples/symbol)
112 @type samples_per_symbol: number or None
113 @param interp_rate: USRP interpolation factor
114 @type interp_rate: integer or None
115 @param converter_rate: converter sample rate in Hz
116 @type converter_rate: number
118 @returns tuple (bitrate, samples_per_symbol, interp_rate)
120 return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
121 interp_rate, converter_rate, _gen_tx_info)
124 def pick_rx_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
125 decim_rate, converter_rate=64e6):
127 Given the 4 input parameters, return at configuration that matches
129 @param bitrate: desired bitrate or None
130 @type bitrate: number or None
131 @param bits_per_symbol: E.g., BPSK -> 1, QPSK -> 2, 8-PSK -> 3
132 @type bits_per_symbol: integer >= 1
133 @param samples_per_symbol: samples/baud (aka samples/symbol)
134 @type samples_per_symbol: number or None
135 @param decim_rate: USRP decimation factor
136 @type decim_rate: integer or None
137 @param converter_rate: converter sample rate in Hz
138 @type converter_rate: number
140 @returns tuple (bitrate, samples_per_symbol, decim_rate)
142 return _pick_bitrate(bitrate, bits_per_symbol, samples_per_symbol,
143 decim_rate, converter_rate, _gen_rx_info)