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Filters reworked for new samplerate

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Mark Qvist 2018-12-30 00:32:19 +01:00
parent 74e0b0d1db
commit 56bed68143
4 changed files with 69 additions and 57 deletions
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90
hardware/AFSK.c
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@ -375,54 +375,53 @@ void AFSK_adc_isr(Afsk *afsk, int8_t currentSample) {
afsk->iirX[0] = afsk->iirX[1];
#if FILTER_CUTOFF == 600
afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) >> 2;
// The above is a simplification of:
// afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) / 3.558147322;
#elif FILTER_CUTOFF == 800
afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) >> 2;
// The above is a simplification of:
// afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) / 2.899043379;
#elif FILTER_CUTOFF == 1200
afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) >> 1;
// The above is a simplification of:
// afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) / 2.228465666;
#elif FILTER_CUTOFF == 1600
afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) >> 1;
// The above is a simplification of:
// afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) / 1.881349100;
#if CONFIG_SAMPLERATE == 9600
#if FILTER_CUTOFF == 600
afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) >> 2;
// The above is a simplification of:
// afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) / 3.558147322;
#else
#error Unsupported filter cutoff!
#endif
#elif CONFIG_SAMPLERATE == 19200
#if FILTER_CUTOFF == 600
afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) / 6;
#else
#error Unsupported filter cutoff!
#endif
#else
#error Unsupported filter cutoff!
#error Unsupported samplerate!
#endif
afsk->iirY[0] = afsk->iirY[1];
#if FILTER_CUTOFF == 600
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] >> 1);
// The above is a simplification of a first-order 600Hz chebyshev filter:
// afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] * 0.4379097269);
#elif FILTER_CUTOFF == 800
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] / 3);
// The above is a simplification of a first-order 800Hz chebyshev filter:
// afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] * 0.3101172565);
#elif FILTER_CUTOFF == 1200
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] / 10);
// The above is a simplification of a first-order 1200Hz chebyshev filter:
// afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] * 0.1025215106);
#elif FILTER_CUTOFF == 1600
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + -1*(afsk->iirY[0] / 17);
// The above is a simplification of a first-order 1600Hz chebyshev filter:
// afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] * -0.0630669239);
#if CONFIG_SAMPLERATE == 9600
#if FILTER_CUTOFF == 600
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] >> 1);
// The above is a simplification of:
// afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] * 0.4379097269);
#else
#error Unsupported filter cutoff!
#endif
#elif CONFIG_SAMPLERATE == 19200
#if FILTER_CUTOFF == 600
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] / 2);
#else
#error Unsupported filter cutoff!
#endif
#else
#error Unsupported filter cutoff!
#error Unsupported samplerate!
#endif
//int8_t freq_disc = (int8_t)fifo_pop(&afsk->delayFifo) * currentSample;
// We put the sampled bit in a delay-line:
// First we bitshift everything 1 left
afsk->sampledBits <<= 1;
// And then add the sampled bit to our delay line
afsk->sampledBits |= (afsk->iirY[1] > 0) ? 0 : 1;
//afsk->sampledBits |= (freq_disc > 0) ? 0 : 1;
// Put the current raw sample in the delay FIFO
fifo_push(&afsk->delayFifo, currentSample);
@ -489,6 +488,7 @@ void AFSK_adc_isr(Afsk *afsk, int8_t currentSample) {
// the last 3 sampled bits. If there is two or
// more 1's, we will assume that the transmitter
// sent us a one, otherwise we assume a zero
uint8_t bits = afsk->sampledBits & 0x07;
if (bits == 0x07 || // 111
bits == 0x06 || // 110
@ -498,15 +498,17 @@ void AFSK_adc_isr(Afsk *afsk, int8_t currentSample) {
afsk->actualBits |= 1;
}
//// Alternative using five bits ////////////////
// uint8_t bits = afsk->sampledBits & 0x0f;
// uint8_t c = 0;
// c += bits & BV(1);
// c += bits & BV(2);
// c += bits & BV(3);
// c += bits & BV(4);
// c += bits & BV(5);
// if (c >= 3) afsk->actualBits |= 1;
//// Alternative using six bits ////////////////
// uint8_t bits = afsk->sampledBits & 0x3F;
// uint8_t c = 0;
// c += bits & _BV(0);
// c += bits & _BV(1);
// c += bits & _BV(2);
// c += bits & _BV(3);
// c += bits & _BV(4);
// c += bits & _BV(5);
// if (c >= 3) afsk->actualBits |= 1;
/////////////////////////////////////////////////
// Now we can pass the actual bit to the HDLC parser.