From 5d69a524f81f234b3fbc41d49ba18d6f6886baba Mon Sep 17 00:00:00 2001 From: jcorgan Date: Thu, 3 Aug 2006 04:51:51 +0000 Subject: Houston, we have a trunk. git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3122 221aa14e-8319-0410-a670-987f0aec2ac5 --- gnuradio-examples/python/gmsk2/pick_bitrate.py | 143 +++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 gnuradio-examples/python/gmsk2/pick_bitrate.py (limited to 'gnuradio-examples/python/gmsk2/pick_bitrate.py') diff --git a/gnuradio-examples/python/gmsk2/pick_bitrate.py b/gnuradio-examples/python/gmsk2/pick_bitrate.py new file mode 100644 index 000000000..b35991caf --- /dev/null +++ b/gnuradio-examples/python/gmsk2/pick_bitrate.py @@ -0,0 +1,143 @@ +# +# Copyright 2005 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 2, 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., 59 Temple Place - Suite 330, +# Boston, MA 02111-1307, USA. +# + +_default_bitrate = 500e3 + +_valid_spbs = (2,3,4,5,6,7) + +def _gen_tx_info(converter_rate): + results = [] + for spb in _valid_spbs: + for interp in range(16, 512 + 1, 4): + bitrate = converter_rate / interp / spb + results.append((bitrate, spb, interp)) + results.sort() + return results + +def _gen_rx_info(converter_rate): + results = [] + for spb in _valid_spbs: + for decim in range(8, 256 + 1, 2): + bitrate = converter_rate / decim / spb + results.append((bitrate, spb, decim)) + results.sort() + return results + +def _filter_info(info, samples_per_baud, xrate): + if samples_per_baud is not None: + info = [x for x in info if x[1] == samples_per_baud] + if xrate is not None: + info = [x for x in info if x[2] == xrate] + return info + +def _pick_best(target_bitrate, bits_per_symbol, info): + """ + @returns tuple (bitrate, samples_per_baud, interp_rate_or_decim_rate) + """ + if len(info) == 0: + raise RuntimeError, "info is zero length!" + + if target_bitrate is None: # return the fastest one + return info[-1] + + # convert bit rate to symbol rate + target_symbolrate = target_bitrate / bits_per_symbol + + # Find the closest matching symbol rate. + # In the event of a tie, the one with the lowest samples_per_baud wins. + # (We already sorted them, so the first one is the one we take) + + best = info[0] + best_delta = abs(target_symbolrate - best[0]) + for x in info[1:]: + delta = abs(target_symbolrate - x[0]) + if delta < best_delta: + best_delta = delta + best = x + + # convert symbol rate back to bit rate + return ((best[0] * bits_per_symbol),) + best[1:] + +def _pick_bitrate(bitrate, bits_per_symbol, samples_per_baud, + xrate, converter_rate, gen_info): + """ + @returns tuple (bitrate, samples_per_baud, interp_rate_or_decim_rate) + """ + if not isinstance(bits_per_symbol, int) or bits_per_symbol < 1: + raise ValueError, "bits_per_symbol must be an int >= 1" + + if samples_per_baud is not None and xrate is not None: # completely determined + return (float(converter_rate) / xrate / samples_per_baud, + samples_per_baud, xrate) + + if bitrate is None and samples_per_baud is None and xrate is None: + bitrate = _default_bitrate + + # now we have a target bitrate and possibly an xrate or + # samples_per_baud constraint, but not both of them. + + return _pick_best(bitrate, bits_per_symbol, + _filter_info(gen_info(converter_rate), samples_per_baud, xrate)) + +# --------------------------------------------------------------------------------------- + +def pick_tx_bitrate(bitrate, bits_per_symbol, samples_per_baud, + interp_rate, converter_rate=128e6): + """ + 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 samples_per_baud: samples/baud (aka samples/symbol) + @type samples_per_baud: 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 + + @returns tuple (bitrate, samples_per_baud, interp_rate) + """ + return _pick_bitrate(bitrate, bits_per_symbol, samples_per_baud, + interp_rate, converter_rate, _gen_tx_info) + + +def pick_rx_bitrate(bitrate, bits_per_symbol, samples_per_baud, + decim_rate, converter_rate=64e6): + """ + 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 samples_per_baud: samples/baud (aka samples/symbol) + @type samples_per_baud: 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 + + @returns tuple (bitrate, samples_per_baud, decim_rate) + """ + return _pick_bitrate(bitrate, bits_per_symbol, samples_per_baud, + decim_rate, converter_rate, _gen_rx_info) -- cgit