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Use IFIR decimator for TPMS.

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This commit is contained in:
Jared Boone 2016-01-02 10:42:40 -08:00
parent e720bfb054
commit 410d4d7fc3
2 changed files with 52 additions and 10 deletions
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35
firmware/baseband/proc_tpms.cpp
View File

@ -26,10 +26,43 @@
#include "i2s.hpp"
using namespace lpc43xx;
#include "dsp_fir_taps.hpp"
static constexpr fir_taps_real<24> taps_200k_decim_0 = {
.pass_frequency_normalized = 100000.0f / 2457600.0f,
.stop_frequency_normalized = 407200.0f / 2457600.0f,
.taps = { {
90, 94, 4, -240, -570, -776, -563, 309,
1861, 3808, 5618, 6710, 6710, 5618, 3808, 1861,
309, -563, -776, -570, -240, 4, 94, 90,
} },
};
static constexpr fir_taps_real<16> taps_200k_decim_1 = {
.pass_frequency_normalized = 100000.0f / 614400.0f,
.stop_frequency_normalized = 207200.0f / 614400.0f,
.taps = { {
-132, -256, 545, 834, -1507, -2401, 4666, 14583,
14583, 4666, -2401, -1507, 834, 545, -256, -132,
} },
};
TPMSProcessor::TPMSProcessor() {
decim_0.configure(taps_200k_decim_0.taps, 33554432);
decim_1.configure(taps_200k_decim_1.taps, 131072);
}
void TPMSProcessor::execute(const buffer_c8_t& buffer) {
/* 2.4576MHz, 2048 samples */
auto decimator_out = decimator.execute(buffer);
const buffer_c16_t dst_buffer {
dst.data(),
dst.size()
};
const auto decim_0_out = decim_0.execute(buffer, dst_buffer);
const auto decim_1_out = decim_1.execute(decim_0_out, dst_buffer);
const auto decimator_out = decim_1_out;
/* 76.8kHz, 64 samples */
feed_channel_stats(decimator_out);

27
firmware/baseband/proc_tpms.hpp
View File

@ -39,22 +39,31 @@
#include <bitset>
// Translate+rectangular filter
// sample=153.6k, deviation=38400, symbol=19200
// Length: 8 taps, 1 symbols, 2 cycles of sinusoid
constexpr std::array<std::complex<float>, 8> rect_taps_153k6_1t_p { {
{ 1.2500000000e-01f, 0.0000000000e+00f }, { 0.0000000000e+00f, 1.2500000000e-01f },
{ -1.2500000000e-01f, 0.0000000000e+00f }, { 0.0000000000e+00f, -1.2500000000e-01f },
{ 1.2500000000e-01f, 0.0000000000e+00f }, { 0.0000000000e+00f, 1.2500000000e-01f },
{ -1.2500000000e-01f, 0.0000000000e+00f }, { 0.0000000000e+00f, -1.2500000000e-01f },
// sample=307.2k, deviation=38400, symbol=19200
// Length: 16 taps, 1 symbols, 2 cycles of sinusoid
constexpr std::array<std::complex<float>, 16> rect_taps_307k2_1t_p { {
{ 6.2500000000e-02f, 0.0000000000e+00f }, { 4.4194173824e-02f, 4.4194173824e-02f },
{ 0.0000000000e+00f, 6.2500000000e-02f }, { -4.4194173824e-02f, 4.4194173824e-02f },
{ -6.2500000000e-02f, 0.0000000000e+00f }, { -4.4194173824e-02f, -4.4194173824e-02f },
{ 0.0000000000e+00f, -6.2500000000e-02f }, { 4.4194173824e-02f, -4.4194173824e-02f },
{ 6.2500000000e-02f, 0.0000000000e+00f }, { 4.4194173824e-02f, 4.4194173824e-02f },
{ 0.0000000000e+00f, 6.2500000000e-02f }, { -4.4194173824e-02f, 4.4194173824e-02f },
{ -6.2500000000e-02f, 0.0000000000e+00f }, { -4.4194173824e-02f, -4.4194173824e-02f },
{ 0.0000000000e+00f, -6.2500000000e-02f }, { 4.4194173824e-02f, -4.4194173824e-02f },
} };
class TPMSProcessor : public BasebandProcessor {
public:
TPMSProcessor();
void execute(const buffer_c8_t& buffer) override;
private:
ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By16 };
dsp::matched_filter::MatchedFilter mf { rect_taps_153k6_1t_p, 4 };
std::array<complex16_t, 512> dst;
dsp::decimate::FIRC8xR16x24FS4Decim4 decim_0;
dsp::decimate::FIRC16xR16x16Decim2 decim_1;
dsp::matched_filter::MatchedFilter mf { rect_taps_307k2_1t_p, 8 };
clock_recovery::ClockRecovery<clock_recovery::FixedErrorFilter> clock_recovery {
38400, 19200, { 0.0555f },