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Merge pull request #243 from F4FXL/FM 

Fix CTCSS value is different when using RXLevel 50 to 99
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Jonathan Naylor 2020-05-01 17:04:05 +01:00 committed by GitHub
parent 5b32fecc0a 0a5c496a3a
commit b027e1d1bf
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 17 additions and 1 deletions
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16
FMCTCSSRX.cpp
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@ -93,7 +93,7 @@ m_rxLevelInverse(1)
uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t threshold, uint8_t level) uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t threshold, uint8_t level)
{ {
m_rxLevelInverse = 511 / q15_t(level); m_rxLevelInverse = q15Division(65535, q15_t(level * 128));
m_coeffDivTwo = 0; m_coeffDivTwo = 0;
@ -179,3 +179,17 @@ void CFMCTCSSRX::reset()
m_result = CTS_NONE; m_result = CTS_NONE;
m_count = 0U; m_count = 0U;
} }
//Taken from https://en.wikipedia.org/wiki/Q_(number_format)#Division
q15_t CFMCTCSSRX::q15Division(q15_t a, q15_t divisor)
{
q31_t a31 = q31_t(a) << 16;
if (((a >> 31) & 1) == ((divisor >> 15) & 1))
a31 += divisor >> 1;
else
a31 -= divisor >> 1;
return a31 / divisor;
}

2
FMCTCSSRX.h
View File

@ -62,6 +62,8 @@ public:
void reset(); void reset();
private: private:
q15_t q15Division(q15_t a, q15_t divisor);
q63_t m_coeffDivTwo; q63_t m_coeffDivTwo;
q31_t m_threshold; q31_t m_threshold;
uint16_t m_count; uint16_t m_count;