mirror of
https://github.com/portapack-mayhem/mayhem-firmware.git
synced 2026-08-20 14:39:01 +00:00
Frederic BORRY
115 lines
4.3 KiB
C++
115 lines
4.3 KiB
C++
/*
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* Copyright (C) 2026 Frederic BORRY - ADRASEC 31
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*
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* This file is part of PortaPack.
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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 2, or (at your option)
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* 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; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __PROC_EPIRB_TX_H__
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#define __PROC_EPIRB_TX_H__
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#include "baseband_processor.hpp"
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#include "baseband_thread.hpp"
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#include "portapack_shared_memory.hpp"
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#include "tonesets.hpp"
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#include <cmath>
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/**
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* Processor used by epirb_tx app to simulate a COSPAS/SARSAT emergency beacon
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* The processor will alternatively:
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* - Send a 406 MHz Manchester encoded BPSK signal containing the beacon information
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* - Send a 127.5 MHz AM distress audio signal
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*/
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class EPIRBTXProcessor : public BasebandProcessor {
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public:
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void execute(const buffer_c8_t& buffer) override;
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void on_message(const Message* const msg) override;
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private:
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// True when the processor has received a configuration message from the app
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bool configured{false};
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// True when in BPSK transmission mode, false for AM transmission mode
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bool mode_bpsk{false};
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// True when the transmission has to be stopped (e.g. at the end of a frame)
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bool end_of_transmission{};
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// I/Q values for current sample (ranging from -128 to 127)
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int8_t re{0}, im{0};
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// Configured pre-count value: used to generate a carrier for config_pre_count samples before starting a frame
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uint32_t config_pre_count = 0;
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// Configured post-count value: used to continue the carrier for config_post_count samples after the end of a frame
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uint32_t config_post_count = 0;
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// Data of the frame to send in BPSK mode
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uint8_t frame_data[18]{0};
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// Size of the frame to send in BPSK mode
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uint8_t frame_data_len = 0;
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// BPSK parameters: Target phase +/-1.1 RAD as per COSPAS/SARSAT specifications
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static constexpr float phase_rad = 1.1f;
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// I/Q values for BPSK (positive phase and negative phase)
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int8_t i_pos = (int8_t)(cos(phase_rad) * 127);
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int8_t q_pos = (int8_t)(sin(phase_rad) * 127);
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int8_t i_neg = i_pos;
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int8_t q_neg = -q_pos;
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// I/Q values for carrier only
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static constexpr int8_t i_carrier = 127;
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static constexpr int8_t q_carrier = 0;
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// COSPAS/SARSAT signal is manchester (2 states per bit) encoded 400 bit/sec
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static const uint32_t samples_per_halfbit = TONES_SAMPLERATE / 400 / 2;
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// Sequencer state for BPSK
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uint32_t sample_counter = 0;
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uint32_t bpsk_pre_count = 0;
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uint32_t bpsk_post_count = 0;
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// Bit position in current byte
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uint32_t bit_index = 0;
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// Byte position in current frame
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uint32_t byte_index = 0;
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// Value of the current byte
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uint8_t current_byte = 0;
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// Value of the current bit
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uint8_t current_bit = 0;
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// Position in the current manchester bit
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bool manchester_half = false; // false = first half
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// 127.5 AM signal parameters
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static const uint32_t sweep_rate = 3; // 3 Hz
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static const uint32_t f_min = 300; // Sweep min frequency (Hz)
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static const uint32_t f_max = 1600; // Sweep max frequency (Hz)
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static const uint32_t freq_span = f_max - f_min;
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// Frequency
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static const uint32_t freq_scale = (1ULL << 32) / TONES_SAMPLERATE;
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static const int32_t center_freq = f_min + (freq_span / 2);
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static const int32_t freq_dev = freq_span / 256;
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// Increments
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static const uint32_t sweep_inc = sweep_rate * freq_scale;
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// Phase accumulators for sweep and audio
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uint32_t sweep_phase = 0;
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uint32_t audio_phase = 0;
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TXProgressMessage txprogress_message{};
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/* NB: Threads should be the last members in the class definition. */
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BasebandThread baseband_thread{TONES_SAMPLERATE, this, baseband::Direction::Transmit};
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};
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#endif
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