94 lines
3.4 KiB
C++
94 lines
3.4 KiB
C++
/* -*- c++ -*- */
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/*
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* gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
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*
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* Copyright (C) 2016, Libre Space Foundation <http://librespacefoundation.org/>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef INCLUDED_SATNOGS_CW_TO_SYMBOL_H
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#define INCLUDED_SATNOGS_CW_TO_SYMBOL_H
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#include <satnogs/api.h>
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#include <gnuradio/sync_block.h>
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#define MIN_WPM 5
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#define MAX_WPM 50
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namespace gr
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{
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namespace satnogs
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{
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/*!
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* \brief The CW to Symbol block tries to translate the input signal
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* into Morse symbols. The input signal should have been already properly
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* filtered and processed. A possible DSP on the input signal may be the
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* squared magnitude or the amplitude of the autocorrelation. Proper filtering
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* that take cares possible spikes may drastically increase the performance
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* of this block.
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*
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* \ingroup satnogs
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*/
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class SATNOGS_API cw_to_symbol : virtual public gr::sync_block
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{
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public:
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typedef boost::shared_ptr<cw_to_symbol> sptr;
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/*!
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* The CW to Symbol block tries to translate the received signal
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* power time-series into Morse symbols.
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*
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* The input stream is the energy of the signal in the time domain.
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* For best results, a proper moving average filter should be applied
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* before.
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*
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* Upon a successful recovery of a symbol it produces an appropriate
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* asynchronous message that can directly be used by the Morse decoder
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* block.
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*
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* @param sampling_rate the sampling rate of the signal
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* @param threshold the activation threshold
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* @param conf_level the confidence level, for the decisions made by
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* the decoder. Higher values, means that the decoder would be more
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* conservative, whereas lower may help in noisy environments but may
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* trigger false alarms too, especially for the case of short pauses
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* symbols
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*
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* @param wpm Morse code Words per Minute
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*
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* @param hysteresis this value represents the hysteresis of a possible
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* filter used before the CW to Symbol block. For example if there is
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* a moving average filter with x taps, the full power of the signal
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* will be available after x samples. The total length of samples with
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* maximum power will be 2*x less. Because the block searches for plateaus
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* with proper durations, this filtering hysteresis should be known.
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* If no such a filter is used, the hysteresis value should be set to zero.
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*/
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static cw_to_symbol::sptr
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make (double sampling_rate, float threshold, float conf_level = 0.9,
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size_t wpm = 20,
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size_t hysteresis = 0);
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virtual void
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set_act_threshold (float thrld) = 0;
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};
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} // namespace satnogs
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} // namespace gr
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#endif /* INCLUDED_SATNOGS_CW_TO_SYMBOL_H */
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