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scramble preamble

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This commit is contained in:
Ahmet Inan 2023-03-05 08:32:13 +01:00
commit 03da985dd0
2 changed files with 8 additions and 0 deletions
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4
decode.cc
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@ -170,6 +170,7 @@ struct Decoder
static const int code_order = 12;
static const int mod_bits = 2;
static const int code_len = 1 << code_order;
static const int meta_len = 128;
static const int symbol_len = 256;
static const int filter_len = 33;
static const int guard_len = symbol_len / 8;
@ -291,6 +292,9 @@ struct Decoder
prev[i] = fdom[first_subcarrier+i];
for (int i = 0; i < subcarrier_count; ++i)
mod_soft(code+mod_bits*i, cons[i], 8);
CODE::MLS seq(0b10000011);
for (int i = 0; i < meta_len; ++i)
code[i] *= nrz(seq());
int oper_mode = hadamard(code);
if (oper_mode != 1) {
std::cerr << "operation mode " << oper_mode << " unsupported." << std::endl;

4
encode.cc
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@ -31,6 +31,7 @@ struct Encoder
static const int mod_bits = 2;
static const int code_order = 12;
static const int code_len = 1 << code_order;
static const int meta_len = 128;
static const int symbol_len = 256;
static const int guard_len = symbol_len / 8;
static const int data_bits = 2048;
@ -93,6 +94,9 @@ struct Encoder
void meta_data(int data)
{
hadamard(code, data);
CODE::MLS seq(0b10000011);
for (int i = 0; i < meta_len; ++i)
code[i] *= nrz(seq());
for (int i = 0; i < subcarrier_count; ++i)
fdom[first_subcarrier+i] *= mod_map(code+mod_bits*i);
symbol();