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Merge pull request #589 from F4FXL/FM_Ext

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Tighten code, enable emphasis
This commit is contained in:
Jonathan Naylor 2020-05-14 22:18:53 +01:00 committed by GitHub
parent 9e52db3ef3 d96e2204bf
commit 56619166b6
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GPG key ID: 4AEE18F83AFDEB23
4 changed files with 37 additions and 28 deletions
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48
FMControl.cpp
View file

@ -20,16 +20,15 @@
#include <string>
#define EMPHASIS_GAIN_DB 0 //Gain needs to be the same for pre an deeemphasis
#define RF_AUDIO_SAMP_RATE 8000
#define FM_AUDIO_BLOCK_SIZE 240
const float EMPHASIS_GAIN_DB = 0.0F; //Gain needs to be the same for pre an deeemphasis
const unsigned int FM_MASK = 0x00000FFFU;
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_incomingRFAudio(1000U, "Incoming RF FM Audio")
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)
{
}
@ -50,9 +49,6 @@ bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
if (m_network == NULL)
return true;
float samples[170U];
unsigned int nSamples = 0U;
m_incomingRFAudio.addData(data + 1U, length - 1U);
unsigned int bufferLength = m_incomingRFAudio.dataSize();
@ -61,14 +57,16 @@ bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
if (bufferLength >= 3U) {
bufferLength = bufferLength - bufferLength % 3U; //round down to nearest multiple of 3
unsigned char bufferData[255];
unsigned char bufferData[255U];
m_incomingRFAudio.getData(bufferData, bufferLength);
unsigned int nSamples = 0;
float samples[85U]; // 255 / 3;
// Unpack the serial data into float values.
for (unsigned int i = 0U; i < bufferLength; i += 3U) {
unsigned short sample1 = 0U;
unsigned short sample2 = 0U;
unsigned int MASK = 0x00000FFFU;
unsigned int pack = 0U;
unsigned char* packPointer = (unsigned char*)&pack;
@ -77,7 +75,7 @@ bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
packPointer[2U] = bufferData[i + 1U];
packPointer[3U] = bufferData[i + 2U];
sample2 = short(pack & MASK);
sample2 = short(pack & FM_MASK);
sample1 = short(pack >> 12);
// Convert from unsigned short (0 - +4095) to float (-1.0 - +1.0)
@ -85,11 +83,11 @@ bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
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]);
//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 short out[170U]; // 85 * 2
unsigned int nOut = 0U;
// Repack the data (8-bit unsigned values containing unsigned 16-bit data)
@ -99,7 +97,7 @@ bool CFMControl::writeModem(const unsigned char* data, unsigned int length)
out[nOut++] = (sample >> 0) & 0xFFU;
}
return m_network->write(out, nOut);
return m_network->write((unsigned char*)out, nOut);
}
return true;
@ -113,23 +111,25 @@ unsigned int CFMControl::readModem(unsigned char* data, unsigned int space)
if (m_network == NULL)
return 0U;
unsigned char netData[300U];
unsigned int length = m_network->read(netData, 270U);
if(space > 252U)
space = 252U;
unsigned char netData[168U];//84 * 2 modem can handle up to 84 samples (252 bytes) at a time
unsigned int length = m_network->read(netData, 168U);
if (length == 0U)
return 0U;
float samples[170U];
float samples[84U];
unsigned int nSamples = 0U;
// Convert the unsigned 16-bit data (+65535 - 0) to float (+1.0 - -1.0)
for (unsigned int i = 0U; i < length; i += 2U) {
unsigned short sample = (netData[i + 0U] << 8) | netData[i + 1U];
samples[nSamples++] = (float(sample) / 32767.0F) - 1.0F;
}
// Pre-emphasise the data and other stuff.
// for (unsigned int i = 0U; i < nSamples; i++)
// samples[i] = m_preemphasis.filter(samples[i]);
//Pre-emphasise the data and other stuff.
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;

4
FMControl.h
View file

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

5
FMNetwork.cpp
View file

@ -107,6 +107,7 @@ unsigned int CFMNetwork::read(unsigned char* data, unsigned int space)
{
assert(data != NULL);
unsigned int bytes = m_buffer.dataSize();
if (bytes == 0U)
return 0U;
@ -114,6 +115,10 @@ unsigned int CFMNetwork::read(unsigned char* data, unsigned int space)
if (bytes < space)
space = bytes;
//we store usignedshorts, therefore ensure we always return and even number of data
if(space > 0 && space % 2 != 0)
space--;//round down to multiple of 2
m_buffer.getData(data, space);
return space;

8
IIRDirectForm1Filter.cpp
View file

@ -21,14 +21,18 @@
#include "math.h"
CIIRDirectForm1Filter::CIIRDirectForm1Filter(float b0, float b1, float b2, float , float a1, float a2, float addtionalGaindB) :
m_x2(0.0F),
m_y2(0.0F),
m_x1(0.0F),
m_y1(0.0F),
m_b0(b0),
m_b1(b1),
m_b2(b2),
m_a1(a1),
m_a2(a2),
m_additionalGainLin(::powf(10.0F, addtionalGaindB / 20.0F))
m_additionalGainLin(0.0F)
{
m_additionalGainLin = ::powf(10.0F, addtionalGaindB / 20.0F);
}
float CIIRDirectForm1Filter::filter(float sample)