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Added class radioCWModulator_F32 for Morse code
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‎radioCWModulator_F32.cpp‎

Lines changed: 207 additions & 0 deletions
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/*
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* radioCWModulator_F32.cpp
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*
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* Created: Bob larkin W7PUA March 2023
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*
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* License: MIT License. Use at your own risk.
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*/
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#include "radioCWModulator_F32.h"
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#include "sinTable512_f32.h"
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void radioCWModulator_F32::update(void) {
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float32_t keyData[128]; // CW key down and up, 0.0f and 1.0f
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float32_t modulateCW[128]; // Storage for data to modulate sine wave
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uint16_t index, i;
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float32_t a, b;
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audio_block_f32_t *blockOut;
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blockOut = AudioStream_F32::allocate_f32(); // Output block
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if (!blockOut) return;
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// A new character cannot enter sendBuffer during an interrupt, but
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// the state IDLE_CW can be created by some other state ending.
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// So it needs to be in the audio sample loop.
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// We always generate CW at 12 ksps. The number of data points in this
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// generation varies to provide 128 output output points after
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// interpolation to 48 or 96 ksps.
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for(i=0; i<nSamplesPerUpdate; i++)
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{
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timeMsF += timeSamplesMs;
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timeMsI = (uint32_t)(0.5 + timeMsF);
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if(!enableXmit) // Just leave the key up and no new characters
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{
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levelCW = 0.0f;
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goto noXmit;
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}
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switch(stateCW)
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{
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case IDLE_CW:
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timeMsF = 0.0f;
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timeMsI = 0;
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if(((indexW-indexR)&0X1FF) > 0) // Get next char, if available
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{
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c = sendBuffer[indexR];
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if (c>95)
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c -= 64; // Convert lc to caps
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else
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c -= 32; // Move subscript to (0, 63)
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ic = mc[(int)c]; // Ch to morse code lookup
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if (c==27) // Long Dash from ';'
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{
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stateCW = LONG_DASH;
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levelCW = 1.0f;
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timeMsF = 0.0f;
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timeMsI = 0;
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}
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else if (ic==0X17) // A space character
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{
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stateCW = WORD_SPACE;
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levelCW = 0.0f;
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timeMsF = 0.0f;
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timeMsI = 0;
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}
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else if(ic>1 && (ic & 1)==0x01)
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{
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stateCW = DASH_CW;
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levelCW = 1.0f;
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timeMsF = 0.0f;
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timeMsI = 0;
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}
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else if(ic>1 && (ic & 1)==0X00)
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{
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stateCW = DOT_CW;
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levelCW = 1.0f;
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timeMsF = 0.0f;
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timeMsI = 0;
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}
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else if(ic==0X01)
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{
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stateCW = IDLE_CW;
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levelCW = 0.0f;
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}
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} // end, if new character
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break;
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case DASH_CW:
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if(timeMsI > dashCW) // Finished dash
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{
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levelCW = 0.0f;
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if(ic>1) ic >>= 1; // Shift right 1
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if(ic==1)
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stateCW = CHAR_SPACE;
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else
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stateCW = DOT_DASH_SPACE;
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timeMsF = 0.0f;
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timeMsI = 0;
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}
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break;
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case DOT_CW:
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if(timeMsI > dotCW)
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{
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levelCW = 0.0f;
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if(ic>1) ic >>= 1; // Shift right 1
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if(ic==1)
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stateCW = CHAR_SPACE;
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else
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stateCW = DOT_DASH_SPACE;
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timeMsF = 0.0f;
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timeMsI = 0;
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}
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break;
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case DOT_DASH_SPACE:
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if(timeMsI > ddCW) // Just finished
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{
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timeMsF = 0.0f;
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timeMsI = 0;
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if(ic>1 && (ic & 1)==0x01)
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{
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stateCW = DASH_CW;
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levelCW = 1.0f;
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}
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else if(ic>1 && (ic & 1)==0X00)
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{
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stateCW = DOT_CW;
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levelCW = 1.0f;
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}
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else
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{
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stateCW = IDLE_CW;
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levelCW = 0.0;
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}
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}
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break;
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case CHAR_SPACE:
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if(timeMsI > chCW+ddCW) // Just finished sending a character
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// chCW+ddCW sounds better than chCW to me.
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{
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indexR++; // Sending is ended, bump the read index
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indexR = indexR & 0X1FF; // Confine to (0, 511)
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timeMsF = 0.0f;
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timeMsI = 0;
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stateCW = IDLE_CW;
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break;
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}
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case WORD_SPACE:
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if(timeMsI > spCW) // Just finished sending a space
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{
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indexR++; // Sending is ended, bump the read index
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indexR = indexR & 0X1FF; // Confine to (0, 511)
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timeMsF = 0.0f;
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timeMsI = 0;
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stateCW = IDLE_CW;
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break;
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}
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case LONG_DASH:
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if(timeMsI > longDashCW) // Just finished sending a long dash
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{
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levelCW = 0.0f;
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stateCW = CHAR_SPACE;
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timeMsF = 0.0f;
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timeMsI = 0;
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break;
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}
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} // end switch
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noXmit:
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keyData[i] = levelCW;
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} // end, over all 128 times
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arm_fir_f32(&GaussLPFInst, keyData, keyData, nSamplesPerUpdate);
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// INTERPOLATE - Interpolate here to support higher sample rates,
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// while using the same spectral LPF. To this point we have 128, 32
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// or 16 "active" data points for 12, 48, or 96ksps.
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//
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// 0 1 2 3 4 5 6 7 8 9 i
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// 0 0 0 0 1 1 1 1 2 2 i/4
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// t 0 0 0 t 0 0 0 t 0 i==4*(i/4)
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//
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if(nSample > 1) // Only needs interpolation if >1
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{
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for(i=0; i<128; i++)
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{
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if( i==(nSample*(1/nSample)) )
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modulateCW[i]= keyData[i/nSample];
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else
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modulateCW[i] = 0.0f;
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}
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arm_fir_f32(&interpolateLPFInst, modulateCW, keyData, 128);
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}
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// Interpolation is done, now amplitude modulate CW onto a sine wave.
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for (i=0; i < 128; i++)
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{
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phaseS += phaseIncrement;
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if (phaseS > 512.0f) phaseS -= 512.0f;
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index = (uint16_t) phaseS;
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float32_t deltaPhase = phaseS - (float32_t)index;
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// Read two nearest values of input value from the sine table
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a = sinTable512_f32[index];
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b = sinTable512_f32[index+1];
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blockOut->data[i] = magnitude*keyData[i]*(a+(b-a)*deltaPhase);
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}
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AudioStream_F32::transmit(blockOut);
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AudioStream_F32::release (blockOut);
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}

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