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Use matched filter for AIS GMSK demodulation demo.

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Less than optimal for plain FSK, but flexible enough to also support GFSK/GMSK. Not at all optimized for SIMD instructions, so may not perform adequately at Bluetooth/GSM rates.
This commit is contained in:
Jared Boone
2015-09-28 11:02:39 -07:00
parent a9c190b6bb
commit 0bc8f551de
2 changed files with 36 additions and 12 deletions
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firmware/baseband/proc_fsk.hpp
+24 -2
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@@ -26,7 +26,7 @@
#include "channel_decimator.hpp"
#include "dsp_decimate.hpp"
#include "dsp_demodulate.hpp"
#include "matched_filter.hpp"
#include "dsp_fir_taps.hpp"
#include "clock_recovery.hpp"
@@ -40,6 +40,20 @@
#include <cstddef>
#include <bitset>
constexpr std::array<std::complex<float>, 8> ais_taps_n { {
{ 0.00533687f, 0.00000000f }, { -0.00667109f, -0.00667109f },
{ -0.00000000f, -0.01334218f }, { -0.05145006f, 0.05145006f },
{ -0.14292666f, 0.00000000f }, { -0.05145006f, -0.05145006f },
{ 0.00000000f, 0.01334218f }, { -0.00667109f, 0.00667109f },
} };
constexpr std::array<std::complex<float>, 8> ais_taps_p { {
{ 0.00533687f, 0.00000000f }, { -0.00667109f, 0.00667109f },
{ -0.00000000f, 0.01334218f }, { -0.05145006f, -0.05145006f },
{ -0.14292666f, -0.00000000f }, { -0.05145006f, 0.05145006f },
{ 0.00000000f, -0.01334218f }, { -0.00667109f, -0.00667109f },
} };
class FSKProcessor : public BasebandProcessor {
public:
FSKProcessor(MessageHandlerMap& message_handlers);
@@ -55,7 +69,15 @@ private:
ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By16 };
const fir_taps_real<64>& channel_filter_taps = taps_64_lp_031_070_tfilter;
dsp::decimate::FIRAndDecimateBy2Complex<64> channel_filter { channel_filter_taps.taps };
dsp::demodulate::FM demod { sampling_rate, 9600 * 2 };
dsp::matched_filter::MatchedFilter mf_0 {
ais_taps_n,
1
};
dsp::matched_filter::MatchedFilter mf_1 {
ais_taps_p,
1
};
clock_recovery::ClockRecovery clock_recovery {
sampling_rate / 4,