31 lines
1.3 KiB
C++
31 lines
1.3 KiB
C++
#pragma once
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#include <stdint.h>
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constexpr int ND = 58; // Data symbols
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constexpr int NS = 21; // Sync symbols (3 @ Costas 7x7)
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constexpr int NN = NS+ND; // Total channel symbols (79)
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// Generate FT8 tone sequence from payload data
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// [IN] payload - 9 byte array consisting of 72 bit payload
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// [IN] i3 - 3 bits containing message type (zero?)
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// [OUT] itone - array of NN (79) bytes to store the generated tones (encoded as 0..7)
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void genft8(const uint8_t *payload, uint8_t i3, uint8_t *itone);
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// Encode an 87-bit message and return a 174-bit codeword.
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// The generator matrix has dimensions (87,87).
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// The code is a (174,87) regular ldpc code with column weight 3.
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// The code was generated using the PEG algorithm.
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// After creating the codeword, the columns are re-ordered according to
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// "colorder" to make the codeword compatible with the parity-check matrix
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// Arguments:
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// * message - array of 87 bits stored as 11 bytes (MSB first)
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// * codeword - array of 174 bits stored as 22 bytes (MSB first)
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void encode174(const uint8_t *message, uint8_t *codeword);
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// Compute 12-bit CRC for a sequence of given number of bits
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// [IN] message - byte sequence (MSB first)
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// [IN] num_bits - number of bits in the sequence
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uint16_t ft8_crc(uint8_t *message, int num_bits);
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