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)