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Reduce the low pass filter a little.

This commit is contained in:
Jonathan Naylor 2020-06-30 15:35:58 +01:00
parent 14d5098018
commit 8d10555dc9
2 changed files with 8 additions and 12 deletions
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18
AX25Demodulator.cpp
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@ -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.

2
AX25Demodulator.h
View File

@ -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;