From 8d10555dc97d186b220e767668e80c49406a51f0 Mon Sep 17 00:00:00 2001 From: Jonathan Naylor Date: Tue, 30 Jun 2020 15:35:58 +0100 Subject: [PATCH] Reduce the low pass filter a little. --- AX25Demodulator.cpp | 18 +++++++----------- AX25Demodulator.h | 2 +- 2 files changed, 8 insertions(+), 12 deletions(-) diff --git a/AX25Demodulator.cpp b/AX25Demodulator.cpp index b59dc6b..98f235c 100644 --- a/AX25Demodulator.cpp +++ b/AX25Demodulator.cpp @@ -30,19 +30,15 @@ const uint16_t DELAY_LEN = 11U; const float32_t SAMPLES_PER_SYMBOL = SAMPLE_RATE / SYMBOL_RATE; const float32_t PLL_LIMIT = SAMPLES_PER_SYMBOL / 2.0F; -const uint32_t LPF_FILTER_LEN = 96U; +const uint32_t LPF_FILTER_LEN = 48U; q15_t LPF_FILTER_COEFFS[] = { - 0, 0, 0, 1, 2, 5, 8, 12, 18, 23, - 29, 33, 36, 36, 33, 25, 13, -5, -28, -57, - -89, -123, -159, -194, -225, -249, -264, -267, -254, -224, - -175, -104, -12, 102, 236, 389, 557, 738, 926, 1117, - 1306, 1486, 1654, 1802, 1927, 2025, 2092, 2126, 2126, 2092, - 2025, 1927, 1802, 1654, 1486, 1306, 1117, 926, 738, 557, - 389, 236, 102, -12, -104, -175, -224, -254, -267, -264, - -249, -225, -194, -159, -123, -89, -57, -28, -5, 13, - 25, 33, 36, 36, 33, 29, 23, 18, 12, 8, - 5, 2, 1, 0, 0, 0 + -2, -8, -17, -28, -40, -47, -47, -34, + -5, 46, 122, 224, 354, 510, 689, 885, + 1092, 1302, 1506, 1693, 1856, 1987, 2077, 2124, + 2124, 2077, 1987, 1856, 1693, 1506, 1302, 1092, + 885, 689, 510, 354, 224, 122, 46, -5, + -34, -47, -47, -40, -28, -17, -8, -2 }; // 64 Hz loop filter. diff --git a/AX25Demodulator.h b/AX25Demodulator.h index 84a98d6..b6b87a4 100644 --- a/AX25Demodulator.h +++ b/AX25Demodulator.h @@ -42,7 +42,7 @@ private: CAX25Frame m_frame; CAX25Twist m_twist; arm_fir_instance_q15 m_lpfFilter; - q15_t m_lpfState[120U]; // NoTaps + BlockSize - 1, 96 + 20 - 1 plus some spare + q15_t m_lpfState[70U]; // NoTaps + BlockSize - 1, 48 + 20 - 1 plus some spare bool* m_delayLine; uint16_t m_delayPos; bool m_nrziState;