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118 lines
4.0 KiB
118 lines
4.0 KiB
/*
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* radioBFSKmodulator_F32
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*
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* Created: Bob Larkin 17 March 2022
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*
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* License: MIT License. Use at your own risk. See corresponding .h file.
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*
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* 2 April 2023 -Corrected to handle outputs from a full buffer. RSL
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* Added int16_t getBufferSpace(). RSL
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*/
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#include "radioBFSKmodulator_F32.h"
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// 513 values of the sine wave in a float array:
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#include "sinTable512_f32.h"
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// 64 entry send buffer check. Sets stateBuffer
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// Returns the number of un-transmitted characters.
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int16_t RadioBFSKModulator_F32::checkBuffer(void) {
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int64_t deltaIndex = indexIn - indexOut;
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if(deltaIndex==0LL)
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stateBuffer = DATA_BUFFER_EMPTY;
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else if(deltaIndex==64LL)
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stateBuffer = DATA_BUFFER_FULL;
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else
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stateBuffer = DATA_BUFFER_PART;
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if(deltaIndex<0LL || deltaIndex>64LL) // Should never happen
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{
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Serial.print("ERROR in Buffer; deltaIndex = ");
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Serial.println(deltaIndex);
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}
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return (int16_t)deltaIndex;
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}
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void RadioBFSKModulator_F32::update(void) {
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audio_block_f32_t *blockFSK;
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uint16_t index, i;
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float32_t vca;
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float32_t a, b;
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// uint32_t tt=micros();
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blockFSK = AudioStream_F32::allocate_f32(); // Get the output block
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if (!blockFSK) return;
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for (i=0; i < blockFSK->length; i++)
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{
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samplePerBitCount++;
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// Each data bit is an integer number of sample periods
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if(samplePerBitCount >= samplesPerDataBit) // Bit transition time
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{
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samplePerBitCount = 0; // Wait a bit period before checking again
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if(bitSendCount < numBits) // Still sending a word, get next bit
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{
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vc = (uint16_t)(currentWord & 1); // Send 0 or 1
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currentWord = currentWord >> 1; // Next bit position
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bitSendCount++;
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}
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else // End of word, get another if possible
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{
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if(stateBuffer != DATA_BUFFER_EMPTY)
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{
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indexOut++; // Just keeps on going, not circular
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checkBuffer();
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currentWord = dataBuffer[indexOut&indexMask];
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// Serial.print(indexIn);
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// Serial.print(" In Out ");
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// Serial.println(indexOut);
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vc = (uint16_t)(currentWord & 1); // Bit to send next
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bitSendCount = 1U; // Count how many bits have been sent
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currentWord = currentWord >> 1;
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}
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else // No word available
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{
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vc = 1; //Idle at logic 1 (Make programmable?)
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}
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} // end, get another word
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} // end, bit transition time
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if(FIRcoeff==NULL) // No LPF being used
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vca = (float32_t)vc;
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else
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{
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// Put latest data point intoFIR LPF buffer
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indexFIRlatest++;
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FIRdata[indexFIRlatest & indexFIRMask] = (float32_t)vc; // Add to buffer
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// Optional FIR LPF
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vca = 0.0f;
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int16_t iiBase16 = (int16_t)(indexFIRlatest & indexFIRMask);
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int16_t iiSize = (int16_t)(indexFIRMask + 1ULL);
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for(int16_t k=0; k<numCoeffs; k++)
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{
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int16_t ii = iiBase16 - k;
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if(ii < 0)
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ii += iiSize;
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vca += FIRcoeff[k]*FIRdata[ii];
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}
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}
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// Modulate baseband vca voltage to sine wave frequency (VCO)
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// pre-multiply phaseIncrement[0]=kp*freq[0] and deltaPhase=kp*deltaFreq
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currentPhase += (phaseIncrement[0] + vca*deltaPhase);
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if (currentPhase > 512.0f) currentPhase -= 512.0f;
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index = (uint16_t) currentPhase;
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float32_t deltaPhase = currentPhase - (float32_t)index;
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/* Read two nearest values of input value from the sin table */
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a = sinTable512_f32[index];
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b = sinTable512_f32[index+1];
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blockFSK->data[i] = magnitude*(a+(b-a)*deltaPhase); // Linear interpolation
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samplePerBitCount++;
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}
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AudioStream_F32::transmit(blockFSK);
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AudioStream_F32::release (blockFSK);
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// Serial.print(" "); Serial.println(micros()-tt);
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}
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