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M17: DataCarrierDetect and SlidingDFT code cleanup

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This commit is contained in:
f4exb 2022-07-27 18:53:40 +02:00
parent a035c42762
commit 023915c144
2 changed files with 42 additions and 44 deletions
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16
modemm17/DataCarrierDetect.h
View File

@ -28,10 +28,7 @@ namespace modemm17 {
template <size_t SampleRate, size_t Accuracy = 1000>
struct DataCarrierDetect
{
using ComplexType = std::complex<float>;
using NDFT = NSlidingDFT<SampleRate, SampleRate / Accuracy, 2>;
NDFT dft_;
NSlidingDFT<SampleRate, SampleRate / Accuracy, 2> dft_;
float ltrigger_;
float htrigger_;
float level_1 = 0.0;
@ -40,9 +37,14 @@ struct DataCarrierDetect
bool triggered_ = false;
DataCarrierDetect(
size_t freq1, size_t freq2,
float ltrigger = 2.0, float htrigger = 5.0)
: dft_({freq1, freq2}), ltrigger_(ltrigger), htrigger_(htrigger)
size_t freq1,
size_t freq2,
float ltrigger = 2.0,
float htrigger = 5.0
) :
dft_({freq1, freq2}),
ltrigger_(ltrigger),
htrigger_(htrigger)
{
}

70
modemm17/SlidingDFT.h
View File

@ -20,23 +20,14 @@ namespace modemm17
template <size_t SampleRate, size_t Frequency, size_t Accuracy = 1000>
class SlidingDFT
{
public:
using ComplexType = std::complex<float>;
static constexpr size_t N = SampleRate / Accuracy;
static constexpr float pi2 = M_PI * 2.0;
static constexpr float kth = float(Frequency) / float(SampleRate);
// We'd like this to be static constexpr, but std::exp is not a constexpr.
ComplexType coeff_;
std::array<float, N> samples_;
ComplexType result_{0,0};
size_t index_ = 0;
size_t prev_index_ = N - 1;
public:
SlidingDFT()
{
samples_.fill(0);
float pi2 = M_PI * 2.0f;
float kth = float(Frequency) / float(SampleRate);
coeff_ = std::exp(-ComplexType{0, 1} * pi2 * kth);
}
@ -44,7 +35,7 @@ public:
{
auto index = index_;
index_ += 1;
if (index_ == N) index_ = 0;
if (index_ == (SampleRate / Accuracy)) index_ = 0;
float delta = sample - samples_[index];
ComplexType result = (result_ + delta) * coeff_;
@ -53,6 +44,13 @@ public:
prev_index_ = index;
return result;
}
private:
ComplexType coeff_;
std::array<float, (SampleRate / Accuracy)> samples_;
ComplexType result_{0,0};
size_t index_ = 0;
size_t prev_index_ = (SampleRate / Accuracy) - 1;
};
/**
@ -70,31 +68,8 @@ public:
template <size_t SampleRate, size_t N, size_t K>
class NSlidingDFT
{
using ComplexType = std::complex<float>;
static constexpr float pi2 = M_PI * 2.0;
// We'd like this to be static constexpr, but std::exp is not a constexpr.
const std::array<ComplexType, K> coeff_;
std::array<float, N> samples_;
std::array<ComplexType, K> result_{0,0};
size_t index_ = 0;
size_t prev_index_ = N - 1;
static constexpr std::array<ComplexType, K>
make_coefficients(const std::array<size_t, K>& frequencies)
{
ComplexType j = ComplexType{0, 1};
std::array<ComplexType, K> result;
for (size_t i = 0; i != K; ++i)
{
float k = float(frequencies[i]) / float(SampleRate);
result[i] = std::exp(-j * pi2 * k);
}
return result;
}
public:
using ComplexType = std::complex<float>;
using result_type = std::array<ComplexType, K>;
/**
@ -130,6 +105,27 @@ public:
samples_[index] = sample;
return result_;
}
private:
const std::array<ComplexType, K> coeff_;
std::array<float, N> samples_;
std::array<ComplexType, K> result_{0,0};
size_t index_ = 0;
size_t prev_index_ = N - 1;
static constexpr std::array<ComplexType, K>
make_coefficients(const std::array<size_t, K>& frequencies)
{
ComplexType j = ComplexType{0, 1};
std::array<ComplexType, K> result;
float pi2 = M_PI * 2.0f;
for (size_t i = 0; i != K; ++i)
{
float k = float(frequencies[i]) / float(SampleRate);
result[i] = std::exp(-j * pi2 * k);
}
return result;
}
};
} // modemm17