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Rescale the coefficient.

This commit is contained in:
Jonathan Naylor 2020-04-19 17:59:04 +01:00
parent a17bd9cc1d
commit 6575cba982
2 changed files with 63 additions and 65 deletions
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126
FMCTCSSRX.cpp
View File

@ -22,58 +22,58 @@
const struct CTCSS_TABLE { const struct CTCSS_TABLE {
uint8_t frequency; uint8_t frequency;
q31_t coeffDivTwo; q31_t coeff;
} CTCSS_TABLE_DATA[] = { } CTCSS_TABLE_DATA[] = {
{ 67U, 2147153298}, { 67U, 131052},
{ 69U, 2147130228}, { 69U, 131051},
{ 71U, 2147103212}, { 71U, 131049},
{ 74U, 2147076297}, { 74U, 131048},
{ 77U, 2147047330}, { 77U, 131046},
{ 79U, 2147016195}, { 79U, 131044},
{ 82U, 2146982775}, { 82U, 131042},
{ 85U, 2146946945}, { 85U, 131040},
{ 88U, 2146907275}, { 88U, 131037},
{ 91U, 2146867538}, { 91U, 131035},
{ 94U, 2146822298}, { 94U, 131032},
{ 97U, 2146785526}, { 97U, 131030},
{100U, 2146747759}, {100U, 131028},
{103U, 2146695349}, {103U, 131024},
{107U, 2146637984}, {107U, 131021},
{110U, 2146578604}, {110U, 131017},
{114U, 2146513835}, {114U, 131013},
{118U, 2146445080}, {118U, 131009},
{123U, 2146370355}, {123U, 131005},
{127U, 2146291161}, {127U, 131000},
{131U, 2146205372}, {131U, 130994},
{136U, 2146112589}, {136U, 130989},
{141U, 2146014479}, {141U, 130983},
{146U, 2145910829}, {146U, 130977},
{151U, 2145796971}, {151U, 130970},
{156U, 2145676831}, {156U, 130962},
{159U, 2145604646}, {159U, 130958},
{162U, 2145547790}, {162U, 130954},
{165U, 2145468230}, {165U, 130949},
{167U, 2145409363}, {167U, 130946},
{171U, 2145324517}, {171U, 130941},
{173U, 2145261046}, {173U, 130937},
{177U, 2145170643}, {177U, 130931},
{179U, 2145102321}, {179U, 130927},
{183U, 2145006080}, {183U, 130921},
{186U, 2144932648}, {186U, 130917},
{189U, 2144830280}, {189U, 130911},
{192U, 2144748638}, {192U, 130906},
{196U, 2144639788}, {196U, 130899},
{199U, 2144555290}, {199U, 130894},
{203U, 2144436713}, {203U, 130887},
{206U, 2144346237}, {206U, 130881},
{210U, 2144217348}, {210U, 130873},
{218U, 2143983951}, {218U, 130859},
{225U, 2143735870}, {225U, 130844},
{229U, 2143622139}, {229U, 130837},
{233U, 2143469001}, {233U, 130827},
{241U, 2143182299}, {241U, 130810},
{250U, 2142874683}, {250U, 130791},
{254U, 2142733729}}; {254U, 130783}};
const uint8_t CTCSS_TABLE_DATA_LEN = 50U; const uint8_t CTCSS_TABLE_DATA_LEN = 50U;
@ -81,7 +81,7 @@ const uint8_t CTCSS_TABLE_DATA_LEN = 50U;
const uint16_t N = 24000U / 4U; const uint16_t N = 24000U / 4U;
CFMCTCSSRX::CFMCTCSSRX() : CFMCTCSSRX::CFMCTCSSRX() :
m_coeffDivTwo(0), m_coeff(0),
m_threshold(0U), m_threshold(0U),
m_count(0U), m_count(0U),
m_q0(0), m_q0(0),
@ -94,12 +94,12 @@ uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t threshold)
{ {
for (uint8_t i = 0U; i < CTCSS_TABLE_DATA_LEN; i++) { for (uint8_t i = 0U; i < CTCSS_TABLE_DATA_LEN; i++) {
if (CTCSS_TABLE_DATA[i].frequency == frequency) { if (CTCSS_TABLE_DATA[i].frequency == frequency) {
m_coeffDivTwo = CTCSS_TABLE_DATA[i].coeffDivTwo; m_coeff = CTCSS_TABLE_DATA[i].coeff;
break; break;
} }
} }
if (m_coeffDivTwo == 0) if (m_coeff == 0)
return 4U; return 4U;
m_threshold = threshold * threshold; m_threshold = threshold * threshold;
@ -113,13 +113,12 @@ bool CFMCTCSSRX::process(const q15_t* samples, uint8_t length)
q31_t q2 = m_q1; q31_t q2 = m_q1;
m_q1 = m_q0; m_q1 = m_q0;
// Q31 multiplication, t3 = m_coeffDivTwo * 2 * m_q1 // Q31 multiplication, t2 = m_coeff * m_q1
q63_t t1 = m_coeffDivTwo * m_q1; q63_t t1 = m_coeff * m_q1;
q31_t t2 = __SSAT(t1 >> 32, 31); q31_t t2 = __SSAT(t1 >> 32, 31);
q31_t t3 = t2 * 2;
// m_q0 = m_coeffDivTwo * m_q1 * 2 - q2 + samples[i] // m_q0 = m_coeff * m_q1 - q2 + samples[i]
m_q0 = t3 - q2 + samples[i]; m_q0 = t2 - q2 + samples[i];
m_count++; m_count++;
if (m_count == N) { if (m_count == N) {
@ -131,15 +130,14 @@ bool CFMCTCSSRX::process(const q15_t* samples, uint8_t length)
q63_t t3 = m_q1 * m_q1; q63_t t3 = m_q1 * m_q1;
q31_t t4 = __SSAT(t3 >> 32, 31); q31_t t4 = __SSAT(t3 >> 32, 31);
// Q31 multiplication, t9 = m_q0 * m_q1 * m_coeffDivTwo * 2 // Q31 multiplication, t8 = m_q0 * m_q1 * m_coeff
q63_t t5 = m_q0 * m_q1; q63_t t5 = m_q0 * m_q1;
q31_t t6 = __SSAT(t5 >> 32, 31); q31_t t6 = __SSAT(t5 >> 32, 31);
q63_t t7 = t6 * m_coeffDivTwo; q63_t t7 = t6 * m_coeff;
q31_t t8 = __SSAT(t7 >> 32, 31); q31_t t8 = __SSAT(t7 >> 32, 31);
q31_t t9 = t8 * 2;
// value = m_q0 * m_q0 + m_q1 * m_q1 - m_q0 * m_q1 * m_coeffDivTwo * 2 // value = m_q0 * m_q0 + m_q1 * m_q1 - m_q0 * m_q1 * m_coeff
q31_t value = t2 + t4 - t9; q31_t value = t2 + t4 - t8;
m_result = value >= m_threshold; m_result = value >= m_threshold;
m_count = 0U; m_count = 0U;

2
FMCTCSSRX.h
View File

@ -32,7 +32,7 @@ public:
void reset(); void reset();
private: private:
q31_t m_coeffDivTwo; q31_t m_coeff;
uint16_t m_threshold; uint16_t m_threshold;
uint16_t m_count; uint16_t m_count;
q31_t m_q0; q31_t m_q0;