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Move division to CTCSSRX, change sample unscaling to 1/rxLevel

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This commit is contained in:
Geoffrey Merck 2020-04-27 11:16:06 +02:00
parent f9530ee82a
commit 4ffaa62855
4 changed files with 31 additions and 27 deletions
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12
FMCTCSSRX.cpp
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@ -86,12 +86,16 @@ m_threshold(0),
m_count(0U),
m_q0(0),
m_q1(0),
m_result(CTS_NONE)
m_result(CTS_NONE),
m_rxLevelInverse(1)
{
}
uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t threshold)
uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t threshold, q15_t rxLevel)
{
// Calculate 1/rxLevel
m_rxLevelInverse = q31_t(q15Division(65535 /* This value should be 32767 (q15 1). But this does not work.*/, rxLevel));
m_coeffDivTwo = 0;
for (uint8_t i = 0U; i < CTCSS_TABLE_DATA_LEN; i++) {
@ -111,6 +115,8 @@ uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t threshold)
CTCSSState CFMCTCSSRX::process(q15_t sample)
{
q63_t sample31 = q31_t(sample) * m_rxLevelInverse;
m_result = m_result & (~CTS_READY);
q31_t q2 = m_q1;
@ -122,7 +128,7 @@ CTCSSState CFMCTCSSRX::process(q15_t sample)
q31_t t3 = t2 * 2;
// m_q0 = m_coeffDivTwo * m_q1 * 2 - q2 + sample
m_q0 = t3 - q2 + q31_t(sample);
m_q0 = t3 - q2 + sample31;
m_count++;
if (m_count == N) {