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implemented differential modulation

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This commit is contained in:
Ahmet Inan 2025-07-05 17:04:27 +02:00
commit 5d257f55ec
2 changed files with 14 additions and 2 deletions
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10
decode.cc
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@ -226,8 +226,14 @@ struct Decoder : Common
demod[i] *= DSP::polar<value>(1, -tse(i+tone_off));
for (int i = 0; i < tone_count; ++i)
chan[i] *= DSP::polar<value>(1, tse(i+tone_off));
for (int i = pilot_off; i < tone_count; i += block_length)
chan[i] = DSP::lerp(chan[i], tone[i], value(0.5));
if (differential) {
for (int i = 0; i < tone_count; ++i)
if (i % block_length != reserved_off)
chan[i] = fdom[bin(i+tone_off)];
} else {
for (int i = pilot_off; i < tone_count; i += block_length)
chan[i] = DSP::lerp(chan[i], tone[i], value(0.5));
}
value sp = 0, np = 0;
for (int i = 0; i < pilot_tones; ++i) {
cmplx hard(1, 0);

6
encode.cc
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@ -37,6 +37,7 @@ struct Encoder : public Common
cmplx kern[symbol_len];
cmplx guard[guard_len];
cmplx tone[tone_count];
cmplx prev[tone_count];
value weight[guard_len];
value papr_min, papr_max;
@ -93,6 +94,11 @@ struct Encoder : public Common
}
void symbol(bool papr_reduction = true, bool guard_interval = true)
{
for (int i = 0; differential && i < tone_count; ++i)
if (!papr_reduction)
prev[i] = 1;
else if (i % block_length != reserved_off)
prev[i] = tone[i] *= prev[i];
for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0;
for (int i = 0; i < tone_count; ++i)