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Add CTCSS removal

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This commit is contained in:
Geoffrey Merck 2020-05-24 19:07:59 +02:00
parent 8b31cb34ff
commit 02d1e2f0ef
2 changed files with 31 additions and 11 deletions
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33
FMControl.cpp
View file

@ -24,20 +24,36 @@
#include <stdio.h>
#endif
const float EMPHASIS_GAIN_DB = 0.0F; //Gain needs to be the same for pre an deeemphasis
const unsigned int FM_MASK = 0x00000FFFU;
const float EMPHASIS_GAIN_DB = 0.0F; //Gain needs to be the same for pre an deeemphasis
const float FILTER_GAIN_DB = 0.0F;
const unsigned int FM_MASK = 0x00000FFFU;
CFMControl::CFMControl(CFMNetwork* network) :
m_network(network),
m_enabled(false),
m_incomingRFAudio(1600U, "Incoming RF FM Audio"),
m_preemphasis(0.3889703155F, -0.32900055326F, 0.0F, 1.0F, 0.2820291817F, 0.0F, EMPHASIS_GAIN_DB),
m_deemphasis(1.0F, 0.2820291817F, 0.0F, 0.3889703155F, -0.32900055326F, 0.0F, EMPHASIS_GAIN_DB)
m_preemphasis (NULL),
m_deemphasis (NULL),
m_filterStage1(NULL),
m_filterStage2(NULL),
m_filterStage3(NULL)
{
m_preemphasis = new CIIRDirectForm1Filter(0.38897032f, -0.32900053f, 0.0f, 1.0f, 0.28202918f, 0.0f, EMPHASIS_GAIN_DB);
m_deemphasis = new CIIRDirectForm1Filter(1.0f,0.28202918f, 0.0f, 0.38897032f, -0.32900053f, 0.0f, EMPHASIS_GAIN_DB);
m_filterStage1 = new CIIRDirectForm1Filter(0.29495028f, 0.0f, -0.29495028f, 1.0f, -0.61384624f, -0.057158668f, FILTER_GAIN_DB);
m_filterStage2 = new CIIRDirectForm1Filter(1.0f, 2.0f, 1.0f, 1.0f, 0.9946123f, 0.6050482f, FILTER_GAIN_DB);
m_filterStage3 = new CIIRDirectForm1Filter(1.0f, -2.0f, 1.0f, 1.0f, -1.8414584f, 0.8804949f, FILTER_GAIN_DB);
}
CFMControl::~CFMControl()
{
delete m_preemphasis ;
delete m_deemphasis ;
delete m_filterStage1;
delete m_filterStage2;
delete m_filterStage3;
}
bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
@ -57,7 +73,6 @@ bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
if (data[0U] != TAG_DATA)
return false;
m_incomingRFAudio.addData(data + 1U, length - 1U);
unsigned int bufferLength = m_incomingRFAudio.dataSize();
if (bufferLength > 255U)
@ -97,8 +112,10 @@ bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
}
//De-emphasise the data and any other processing needed (maybe a low-pass filter to remove the CTCSS)
for (unsigned int i = 0U; i < nSamples; i++)
samples[i] = m_deemphasis.filter(samples[i]);
for (unsigned int i = 0U; i < nSamples; i++) {
samples[i] = m_deemphasis->filter(samples[i]);
samples[i] = m_filterStage3->filter(m_filterStage2->filter(m_filterStage1->filter(samples[i])));
}
#if defined(DUMP_RF_AUDIO)
if(audiofile != NULL)
@ -152,7 +169,7 @@ unsigned int CFMControl::readModem(unsigned char* data, unsigned int space)
//Pre-emphasise the data and other stuff.
for (unsigned int i = 0U; i < nSamples; i++)
samples[i] = m_preemphasis.filter(samples[i]);
samples[i] = m_preemphasis->filter(samples[i]);
// Pack the floating point data (+1.0 to -1.0) to packed 12-bit samples (+2047 - -2048)
unsigned int pack = 0U;

9
FMControl.h
View file

@ -26,7 +26,7 @@
// Uncomment this to dump audio to a raw audio file
// The file will be written in same folder as executable
// Toplay the file : aplay -f FLOAT_LE -c1 -r8000 -t raw audiodump.bin
//#define DUMP_RF_AUDIO
// #define DUMP_RF_AUDIO
class CFMControl {
public:
@ -45,8 +45,11 @@ private:
CFMNetwork* m_network;
bool m_enabled;
CRingBuffer<unsigned char> m_incomingRFAudio;
CIIRDirectForm1Filter m_preemphasis;
CIIRDirectForm1Filter m_deemphasis;
CIIRDirectForm1Filter * m_preemphasis;
CIIRDirectForm1Filter * m_deemphasis;
CIIRDirectForm1Filter * m_filterStage1;
CIIRDirectForm1Filter * m_filterStage2;
CIIRDirectForm1Filter * m_filterStage3;
};
#endif