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https://github.com/aicodix/modem.git
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added support for various operation modes:
mode 2: 8PSK, 2700 Hz bandwidth and about 10 seconds long mode 3: 8PSK, 2500 Hz bandwidth and about 11 seconds long mode 4: QPSK, 2500 Hz bandwidth and about 16 seconds long mode 5: QPSK, 2250 Hz bandwidth and about 18 seconds long
This commit is contained in:
Ahmet Inan
parent
fa1cc128be
commit
2645f96056
2 changed files with 169 additions and 46 deletions
101
encode.cc
101
encode.cc
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@ -25,13 +25,11 @@ Copyright 2021 Ahmet Inan <inan@aicodix.de>
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template <typename value, typename cmplx, int rate>
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struct Encoder
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{
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typedef PhaseShiftKeying<8, cmplx, int8_t> Mod;
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static const int symbol_len = (1280 * rate) / 8000;
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static const int guard_len = symbol_len / 8;
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static const int ldpc_bits = 64800;
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static const int bch_bits = ldpc_bits - 21600;
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static const int data_bits = bch_bits - 12 * 16;
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static const int cons_cnt = ldpc_bits / Mod::BITS;
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static const int mls0_len = 127;
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static const int mls0_poly = 0b10001001;
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static const int mls1_len = 255;
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@ -53,6 +51,9 @@ struct Encoder
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cmplx temp[symbol_len];
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cmplx guard[guard_len];
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cmplx papr_min, papr_max;
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int oper_mode;
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int mod_bits;
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int cons_cnt;
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int code_cols;
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int code_rows;
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int code_off;
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@ -170,13 +171,25 @@ struct Encoder
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fdom[bin(i+mls1_off)] *= nrz(seq4());
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symbol();
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}
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cmplx mod_map(int8_t *b)
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{
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switch (oper_mode) {
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case 2:
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case 3:
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return PhaseShiftKeying<8, cmplx, int8_t>::map(b);
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case 4:
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case 5:
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return PhaseShiftKeying<4, cmplx, int8_t>::map(b);
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}
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return 0;
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}
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void interleave()
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{
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for (int i = 0; i < cons_cnt; ++i)
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for (int k = 0; k < Mod::BITS; ++k)
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bint[Mod::BITS*i+k] = code[cons_cnt*k+i];
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for (int k = 0; k < mod_bits; ++k)
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bint[mod_bits*i+k] = code[cons_cnt*k+i];
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}
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Encoder(DSP::WritePCM<value> *pcm, uint8_t *inp, int freq_off, uint64_t call_sign, int code_cols) :
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Encoder(DSP::WritePCM<value> *pcm, uint8_t *inp, int freq_off, uint64_t call_sign, int oper_mode) :
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pcm(pcm), crc0(0xA8F4), bchenc0({
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0b100011101, 0b101110111, 0b111110011, 0b101101001,
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0b110111101, 0b111100111, 0b100101011, 0b111010111,
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@ -188,8 +201,30 @@ struct Encoder
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0b10101101001010101, 0b10001111100101111, 0b11111011110110101,
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0b11010111101100101, 0b10111001101100111, 0b10000111010100001,
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0b10111010110100111, 0b10011101000101101, 0b10001101011100011}),
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code_cols(code_cols), code_rows(cons_cnt / code_cols)
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oper_mode(oper_mode)
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{
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switch (oper_mode) {
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case 2:
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code_cols = 432;
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mod_bits = 3;
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break;
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case 3:
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code_cols = 400;
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mod_bits = 3;
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break;
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case 4:
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code_cols = 400;
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mod_bits = 2;
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break;
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case 5:
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code_cols = 360;
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mod_bits = 2;
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break;
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default:
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return;
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}
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cons_cnt = ldpc_bits / mod_bits;
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code_rows = cons_cnt / code_cols;
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int offset = (freq_off * symbol_len) / rate;
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code_off = offset - code_cols / 2;
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mls0_off = offset - mls0_len + 1;
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@ -197,7 +232,7 @@ struct Encoder
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papr_min = cmplx(1000, 1000), papr_max = cmplx(-1000, -1000);
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pilot_block();
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schmidl_cox();
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meta_data((call_sign << 8) | 2);
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meta_data((call_sign << 8) | oper_mode);
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pilot_block();
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bchenc1(inp, inp+data_bits/8, data_bits);
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for (int i = 0; i < bch_bits; ++i)
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@ -207,14 +242,14 @@ struct Encoder
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CODE::MLS seq3(mls3_poly), seq4(mls4_poly);
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for (int j = 0; j < code_rows; ++j) {
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for (int i = 0; i < code_cols; ++i) {
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cmplx con = Mod::map(bint+Mod::BITS*(code_cols*j+i));
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cmplx con = mod_map(bint+mod_bits*(code_cols*j+i));
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con = cmplx(con.real() * nrz(seq3()), con.imag() * nrz(seq4()));
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fdom[bin(i+code_off)] *= con;
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}
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symbol();
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}
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schmidl_cox();
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meta_data((call_sign << 8) | 2);
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meta_data((call_sign << 8) | oper_mode);
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pilot_block();
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for (int i = 0; i < symbol_len; ++i)
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fdom[i] = 0;
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@ -244,8 +279,8 @@ long long int base37_encoder(const char *str)
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int main(int argc, char **argv)
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{
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if (argc < 6 || argc > 8) {
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std::cerr << "usage: " << argv[0] << " OUTPUT RATE BITS CHANNELS INPUT [OFFSET] [CALLSIGN]" << std::endl;
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if (argc < 6 || argc > 9) {
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std::cerr << "usage: " << argv[0] << " OUTPUT RATE BITS CHANNELS INPUT [OFFSET] [CALLSIGN] [MODE]" << std::endl;
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return 1;
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}
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@ -259,11 +294,6 @@ int main(int argc, char **argv)
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if (argc >= 7)
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freq_off = std::atoi(argv[6]);
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if ((output_chan == 1 && freq_off < 1350) || freq_off < 1350 - output_rate / 2 || freq_off > output_rate / 2 - 1350) {
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std::cerr << "Unsupported frequency offset." << std::endl;
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return 1;
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}
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long long int call_sign = base37_encoder("ANONYMOUS");
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if (argc >= 8)
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call_sign = base37_encoder(argv[7]);
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@ -273,6 +303,35 @@ int main(int argc, char **argv)
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return 1;
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}
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int oper_mode = 2;
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if (argc >= 9)
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oper_mode = std::atoi(argv[8]);
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if (oper_mode < 2 || oper_mode > 5) {
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std::cerr << "Unsupported operation mode." << std::endl;
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return 1;
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}
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int band_width;
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switch (oper_mode) {
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case 2:
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band_width = 2700;
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break;
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case 3:
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case 4:
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band_width = 2500;
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break;
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case 5:
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band_width = 2250;
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break;
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default:
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return 1;
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}
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if ((output_chan == 1 && freq_off < band_width / 2) || freq_off < band_width / 2 - output_rate / 2 || freq_off > output_rate / 2 - band_width / 2) {
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std::cerr << "Unsupported frequency offset." << std::endl;
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return 1;
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}
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typedef float value;
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typedef DSP::Complex<value> cmplx;
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@ -281,7 +340,7 @@ int main(int argc, char **argv)
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std::cerr << "Couldn't open file \"" << input_name << "\" for reading." << std::endl;
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return 1;
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}
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const int code_len = 64800 / 8, code_cols = 432;
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const int code_len = 64800 / 8;
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const int data_len = code_len - (12 * 16 + 21600) / 8;
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uint8_t *input_data = new uint8_t[code_len];
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for (int i = 0; i < data_len; ++i)
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@ -291,16 +350,16 @@ int main(int argc, char **argv)
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output_file.silence(output_rate);
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switch (output_rate) {
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case 8000:
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delete new Encoder<value, cmplx, 8000>(&output_file, input_data, freq_off, call_sign, code_cols);
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delete new Encoder<value, cmplx, 8000>(&output_file, input_data, freq_off, call_sign, oper_mode);
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break;
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case 16000:
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delete new Encoder<value, cmplx, 16000>(&output_file, input_data, freq_off, call_sign, code_cols);
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delete new Encoder<value, cmplx, 16000>(&output_file, input_data, freq_off, call_sign, oper_mode);
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break;
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case 44100:
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delete new Encoder<value, cmplx, 44100>(&output_file, input_data, freq_off, call_sign, code_cols);
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delete new Encoder<value, cmplx, 44100>(&output_file, input_data, freq_off, call_sign, oper_mode);
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break;
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case 48000:
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delete new Encoder<value, cmplx, 48000>(&output_file, input_data, freq_off, call_sign, code_cols);
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delete new Encoder<value, cmplx, 48000>(&output_file, input_data, freq_off, call_sign, oper_mode);
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break;
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default:
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std::cerr << "Unsupported sample rate." << std::endl;
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