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cnlohr
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/**
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MIT-like-non-ai-license
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Copyright (c) 2024 Charles Lohr "CNLohr"
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the two following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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In addition the following restrictions apply:
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1. The Software and any modifications made to it may not be used for the
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purpose of training or improving machine learning algorithms, including but not
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limited to artificial intelligence, natural language processing, or data
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mining. This condition applies to any derivatives, modifications, or updates
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based on the Software code. Any usage of the Software in an AI-training dataset
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is considered a breach of this License.
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2. The Software may not be included in any dataset used for training or
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improving machine learning algorithms, including but not limited to artificial
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intelligence, natural language processing, or data mining.
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3. Any person or organization found to be in violation of these restrictions
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will be subject to legal action and may be held liable for any damages
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resulting from such use.
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If any term is unenforcable, other terms remain in-force.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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**/
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#ifndef _SIGGEN_H
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#define _SIGGEN_H
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#include <string.h>
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#include "../../../lib/LoRa-SDR-Code.h"
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#define SF_NUMBER 10
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// This is MEGA overkill. No way would we ever use them all.
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#define MAX_SYMBOLS 2070
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// https://electronics.stackexchange.com/questions/278192/understanding-the-relationship-between-lora-chips-chirps-symbols-and-bits
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// Has some good hints
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// At 125kHz
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// https://medium.com/@prajzler/what-is-lora-the-fundamentals-79a5bb3e6dec
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// With SF5, You get 3906 chips/second "Symbol Rate" (Included to help with math division)
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// With SF7, You get 976 chips/second / 5469 bits/sec
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// 7 bits per symbol (I think)
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// 7 * 4/5 = 5.6 data bits per symbol.
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// https://wirelesspi.com/understanding-lora-phy-long-range-physical-layer/ says 7 for SF7
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#define MARK_FROM_SF0 (1<<SF_NUMBER)
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// Determined experimentally, but this is the amount you have to divide the chip by to
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// Fully use the 125000 Hz channel Bandwidth.
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//#define DESPREAD (50*MARK_FROM_SF6)
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#define CHIPRATE 8 // chirp length for SF0, in us
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#define CHIPSSPREAD ((uint32_t)(240ULL*MARK_FROM_SF0*CHIPRATE))
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#define PREAMBLE_CHIRPS 10
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#define CODEWORD_LENGTH 2
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int symbols_len = 1;
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uint16_t symbols[MAX_SYMBOLS];
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uint32_t quadsetcount;
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int32_t quadsets[MAX_SYMBOLS*4+PREAMBLE_CHIRPS*4+9+CODEWORD_LENGTH*4];
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int32_t * AddChirp( int32_t * qso, int offset, int verneer )
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{
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offset = offset * CHIPSSPREAD / (MARK_FROM_SF0);
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offset += verneer;
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*(qso++) = (CHIPSSPREAD * 0 / 4 + offset + CHIPSSPREAD ) % CHIPSSPREAD;
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*(qso++) = (CHIPSSPREAD * 1 / 4 + offset + CHIPSSPREAD ) % CHIPSSPREAD;
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*(qso++) = (CHIPSSPREAD * 2 / 4 + offset + CHIPSSPREAD ) % CHIPSSPREAD;
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*(qso++) = (CHIPSSPREAD * 3 / 4 + offset + CHIPSSPREAD ) % CHIPSSPREAD;
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return qso;
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}
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static void SigSetupTest()
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{
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memset( symbols, 0, sizeof( symbols ) );
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uint8_t payload_in[258] = { 0x40/*0x48*/, 0xcc/*0x45*/, 0xde, 0x55, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22};
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int payload_in_size = 6;
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static uint8_t uctr;
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payload_in[4] = uctr++;
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int _rdd = 0; // 1 = 4/5, 4 = 4/8 Coding Rate
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int r = CreateMessageFromPayload( symbols, &symbols_len, MAX_SYMBOLS, SF_NUMBER, 4, payload_in, payload_in_size );
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if( r < 0 )
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{
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printf( "Error generating stream: %d\n", r );
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quadsetcount = 0;
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return;
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}
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int j;
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//for( j = 0; j < symbols_len; j++ )
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// symbols[j] = 255 - symbols[j];
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quadsetcount = 0;
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int32_t * qso = quadsets;
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for( j = 0; j < PREAMBLE_CHIRPS; j++ )
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{
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qso = AddChirp( qso, 0, 0 );
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}
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uint8_t syncword = 0x43;
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#if SF_NUMBER <= 6
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#define CODEWORD_SHIFT 2 // XXX TODO: No idea what this would do here! XXX This is probably wrong.
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#elif SF_NUMBER >= 11
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#define CODEWORD_SHIFT 5 // XXX TODO: Unknown for SF11, SF12 Might be 3?
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#else
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#define CODEWORD_SHIFT 3
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#endif
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if( CODEWORD_LENGTH > 0 )
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qso = AddChirp( qso, ( ( syncword & 0xf ) << CODEWORD_SHIFT ), 0 );
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if( CODEWORD_LENGTH > 1 )
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qso = AddChirp( qso, ( ( ( syncword & 0xf0 ) >> 4 ) << CODEWORD_SHIFT ), 0 );
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*(qso++) = -(CHIPSSPREAD * 0 / 4 )-1;
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*(qso++) = -(CHIPSSPREAD * 1 / 4 )-1;
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*(qso++) = -(CHIPSSPREAD * 2 / 4 )-1;
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*(qso++) = -(CHIPSSPREAD * 3 / 4 )-1;
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*(qso++) = -(CHIPSSPREAD * 0 / 4 )-1;
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*(qso++) = -(CHIPSSPREAD * 1 / 4 )-1;
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*(qso++) = -(CHIPSSPREAD * 2 / 4 )-1;
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*(qso++) = -(CHIPSSPREAD * 3 / 4 )-1;
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*(qso++) = -(CHIPSSPREAD * 0 / 4 )-1;
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if( SF_NUMBER <= 6 )
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{
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// Two additional upchirps with SF6 https://github.com/tapparelj/gr-lora_sdr/issues/74#issuecomment-1891569580
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for( j = 0; j < 2; j++ )
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{
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qso = AddChirp( qso, 0, 0 );
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}
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}
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for( j = 0; j < symbols_len; j++ )
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{
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int ofs = symbols[j];
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//ofs = ofs ^ ((MARK_FROM_SF6<<6) -1);
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//ofs &= (MARK_FROM_SF6<<6) -1;
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qso = AddChirp( qso, ofs, 0 );
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}
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quadsetcount = qso - quadsets;
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// printf( "--- %d %d %d\n", symbols_len, quadsetcount, CHIPSSPREAD/4 );
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}
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static int32_t SigGen( uint32_t Frame240MHz, uint32_t codeTarg )
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{
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// TODO: Get some of these encode things going: https://github.com/myriadrf/LoRa-SDR/blob/master/LoRaCodes.hpp
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// frame = 0...240000000
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uint32_t sectionQuarterNumber = Frame240MHz / (CHIPSSPREAD/4);
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if( sectionQuarterNumber >= quadsetcount )
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return -codeTarg;
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int32_t quadValue = quadsets[sectionQuarterNumber];
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uint32_t placeInQuad = Frame240MHz % (CHIPSSPREAD/4);
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if( quadValue >= 0 )
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return ( ( quadValue + placeInQuad ) % CHIPSSPREAD); // Up-Chirp
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else
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return ( ( quadValue - placeInQuad + CHIPSSPREAD ) % CHIPSSPREAD ); // Down-Chirp
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#if 0
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// Let's say 1ms per sweep.
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int32_t sectionQuarterNumber = Frame240MHz / (CHIPSSPREAD/4);
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uint32_t placeInSweep = Frame240MHz % CHIPSSPREAD;
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// 2400 edge-to-edge =
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if( sectionQuarterNumber < 0 ) return -codeTarg;
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sectionQuarterNumber -= PREAMBLE_CHIRPS*4;
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// Preamble Start
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if( sectionQuarterNumber < 0 )
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{
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return ((placeInSweep /*+ 240000/2*/) % CHIPSSPREAD) / DESPREAD;
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}
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// Last 2 codes here are for the sync word.
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#define SYNC_WORD
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#ifdef SYNC_WORD
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// https://static1.squarespace.com/static/54cecce7e4b054df1848b5f9/t/57489e6e07eaa0105215dc6c/1464376943218/Reversing-Lora-Knight.pdf
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// Says that this does not exist. but, it does seem to exist in some of their waterfalls.
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sectionQuarterNumber -= 4*2;
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// Two symbols
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if( sectionQuarterNumber < 0 )
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{
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int32_t chirp = (8+sectionQuarterNumber)/4;
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uint32_t SYNCWORD = (((0x34)>>(4-chirp*4)) & 0xf)<<3; //0x34 for some vendors?
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int32_t offset = SYNCWORD * CHIPSSPREAD / (MARK_FROM_SF7*128);
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return (( placeInSweep + offset) % CHIPSSPREAD) / DESPREAD;
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}
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#endif
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/*
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EXTRA NOTES: lora-grc says to look for sync word 18
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*/
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sectionQuarterNumber -= 9;
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if( sectionQuarterNumber < 0 )
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{
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// Down-Sweeps for Sync
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return ((CHIPSSPREAD-placeInSweep/*+240000/2*/) % CHIPSSPREAD) / DESPREAD;
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}
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uint32_t chirp = (sectionQuarterNumber)/4;
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if( chirp < symbols_len )
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{
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placeInSweep += (CHIPSSPREAD*3/4);
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uint32_t offset = ( symbols[chirp] + 0 ) * CHIPSSPREAD / (MARK_FROM_SF7*128);
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fplv = ((placeInSweep + offset) % CHIPSSPREAD) / DESPREAD;
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return fplv;
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}
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else
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{
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return -codeTarg;
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//return -1;
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}
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#endif
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}
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/*
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A real semtech SX1276 will produce 16 symbols at SF8 if
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Given 2 byte payload, CRC explicit header.
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Given 3 bytes of payload, that goes up to 24 symbols.
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[HEADER] [HEADER*0.5] [HEADER] **An extra byte** [PAYLOAD] [PAYLOAD] [PAYLOAD] [CRC] [CRC] << Does not fit.
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Payload sizes:
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-5 would be 8 (Considering CRC would be -3 bytes)
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-4 would be 8
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-3 would be 8
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-2 would be 8
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-1 would be 16
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0 would be 16
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1 byte: 16 symbols. (Include CRC so 3 bytes)
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2 byte: 16 symbols. (Include CRC so 4 bytes)
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// theoreteically, 2 bytes + 2 crc should fit nicely into 16 symbols (or 8 bytes) BUT 3+2 (5) does not.
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3 byte: 24 symbols. (Include CRC so 5 bytes)
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4 byte: 24 symbols
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5 byte: 24 symbols.
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6 byte: 24 symbols.
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7 byte: 32 symbols.
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8 byte: 32 symbols.
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9 byte: 32 symbols.
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10 byte: 32 symbols.
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11 byte: 40 symbols.
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That means there's
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*/
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#endif
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