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Merge pull request #585 from F4FXL/FM_Ext

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Handle modem FM audio
This commit is contained in:
Jonathan Naylor 2020-05-10 21:07:14 +01:00 committed by GitHub
parent 3299913003 008bfee6b9
commit 7be89b91ea
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 51 additions and 36 deletions
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82
FMControl.cpp
View file

@ -21,12 +21,14 @@
#include <string>
#define EMPHASIS_GAIN_DB 0 //Gain needs to be the same for pre an deeemphasis
#define RF_AUDIO_SAMP_RATE 8000
CFMControl::CFMControl(CFMNetwork* network) :
m_network(network),
m_enabled(false),
m_preemphasis(0.3889703087993727F, -0.3290005228984741F, 0.0F, 1.0F, 0.282029168302153F, 0.0F, EMPHASIS_GAIN_DB),
m_deemphasis(1.0F, 0.282029168302153F, 0.0F, 0.3889703087993727F, -0.3290005228984741F, 0.0F, EMPHASIS_GAIN_DB)
// m_preemphasis(0.3889703087993727F, -0.3290005228984741F, 0.0F, 1.0F, 0.282029168302153F, 0.0F, EMPHASIS_GAIN_DB),
// m_deemphasis(1.0F, 0.282029168302153F, 0.0F, 0.3889703087993727F, -0.3290005228984741F, 0.0F, EMPHASIS_GAIN_DB),
m_incomingRFAudio(1000U, "Incoming RF FM Audio")
{
}
@ -45,42 +47,54 @@ bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
float samples[170U];
unsigned int nSamples = 0U;
// Unpack the serial data into float values.
for (unsigned int i = 0U; i < length; i += 3U) {
unsigned short sample1 = 0U;
unsigned short sample2 = 0U;
unsigned int MASK = 0x00000FFFU;
m_incomingRFAudio.addData(data, length);
unsigned int bufferLength = m_incomingRFAudio.dataSize();
unsigned int pack = 0U;
unsigned char* packPointer = (unsigned char*)&pack;
if(bufferLength >= 3) {
bufferLength = bufferLength - bufferLength % 3; //round down to nearest multiple of 3
unsigned char bufferData[bufferLength];
m_incomingRFAudio.getData(bufferData, bufferLength);
packPointer[1U] = data[i];
packPointer[2U] = data[i + 1U];
packPointer[3U] = data[i + 2U];
// Unpack the serial data into float values.
for (unsigned int i = 0U; i < length; i += 3U) {
unsigned short sample1 = 0U;
unsigned short sample2 = 0U;
unsigned int MASK = 0x00000FFFU;
sample2 = (short)(pack & MASK);
sample1 = (short)(pack >> 12);
unsigned int pack = 0U;
unsigned char* packPointer = (unsigned char*)&pack;
// Convert from unsigned short (0 - +4095) to float (-1.0 - +1.0)
samples[nSamples++] = (float(sample1) - 2048.0F) / 2048.0F;
samples[nSamples++] = (float(sample2) - 2048.0F) / 2048.0F;
packPointer[1U] = bufferData[i];
packPointer[2U] = bufferData[i + 1U];
packPointer[3U] = bufferData[i + 2U];
sample2 = (short)(pack & MASK);
sample1 = (short)(pack >> 12);
// Convert from unsigned short (0 - +4095) to float (-1.0 - +1.0)
samples[nSamples++] = (float(sample1) - 2048.0F) / 2048.0F;
samples[nSamples++] = (float(sample2) - 2048.0F) / 2048.0F;
}
// 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]);
unsigned char out[350U];
unsigned int nOut = 0U;
// Repack the data (8-bit unsigned values containing unsigned 16-bit data)
for (unsigned int i = 0U; i < nSamples; i++) {
unsigned short sample = (unsigned short)((samples[i] + 1.0F) * 32767.0F + 0.5F);
out[nOut++] = (sample >> 8) & 0xFFU;
out[nOut++] = (sample >> 0) & 0xFFU;
}
return m_network->write(out, nOut);
}
// 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]);
unsigned char out[350U];
unsigned int nOut = 0U;
// Repack the data (8-bit unsigned values containing unsigned 16-bit data)
for (unsigned int i = 0U; i < nSamples; i++) {
unsigned short sample = (unsigned short)((samples[i] + 1.0F) * 32767.0F + 0.5F);
out[nOut++] = (sample >> 8) & 0xFFU;
out[nOut++] = (sample >> 0) & 0xFFU;
}
return m_network->write(out, nOut);
return 0U;
}
unsigned int CFMControl::readModem(unsigned char* data, unsigned int space)
@ -105,8 +119,8 @@ 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]);
// for (unsigned int i = 0U; i < nSamples; 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;

5
FMControl.h
View file

@ -39,8 +39,9 @@ public:
private:
CFMNetwork* m_network;
bool m_enabled;
CIIRDirectForm1Filter m_preemphasis;
CIIRDirectForm1Filter m_deemphasis;
// CIIRDirectForm1Filter m_preemphasis;
// CIIRDirectForm1Filter m_deemphasis;
CRingBuffer<unsigned char> m_incomingRFAudio;
};
#endif