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300 baud modulator implemented

This commit is contained in:
Mark Qvist 2019-01-07 13:41:49 +01:00
parent 3f5af2b26b
commit 7f5fe36cc2
2 changed files with 30 additions and 16 deletions
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16
hardware/AFSK.c
View File

@ -399,13 +399,25 @@ void AFSK_adc_isr(Afsk *afsk, int8_t currentSample) {
afsk->iirX[0] = afsk->iirX[1];
#if CONFIG_ADC_SAMPLERATE == 9600
#if CONFIG_ADC_SAMPLERATE == 4800
#if FILTER_CUTOFF == 600
#define IIR_GAIN 2 // Really 2.228465666
#define IIR_POLE 10 // Really Y[0] * 0.1025215106
afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) / IIR_GAIN;
afsk->iirY[0] = afsk->iirY[1];
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] / IIR_POLE);
#else
#error Unsupported filter cutoff!
#endif
#elif CONFIG_ADC_SAMPLERATE == 9600
#if FILTER_CUTOFF == 500
#define IIR_GAIN 4 // Really 4.082041675
#define IIR_POLE 2 // Really Y[0] * 0.5100490981
afsk->iirX[1] = ((int8_t)fifo_pop(&afsk->delayFifo) * currentSample) / IIR_GAIN;
afsk->iirY[0] = afsk->iirY[1];
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] / 2);
afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] / IIR_POLE);
#else
#error Unsupported filter cutoff!

28
hardware/AFSK.h
View File

@ -46,9 +46,12 @@ inline static uint8_t sinSample(uint16_t i) {
#define CONFIG_AFSK_TRAILER_LEN 25UL
#define BIT_STUFF_LEN 5
#define BITRATE 1200
#define BITRATE 300
#if BITRATE == 1200
#if BITRATE == 300
#define CONFIG_ADC_SAMPLERATE 4800UL
#define CONFIG_DAC_SAMPLERATE 19200UL
#elif BITRATE == 1200
#define CONFIG_ADC_SAMPLERATE 9600UL
#define CONFIG_DAC_SAMPLERATE 19200UL
#elif BITRATE == 2400
@ -63,7 +66,9 @@ inline static uint8_t sinSample(uint16_t i) {
#define DAC_TICKS_BETWEEN_SAMPLES ((((CPU_FREQ+FREQUENCY_CORRECTION)) / CONFIG_DAC_SAMPLERATE) - 1)
// TODO: Maybe revert to only looking at two samples
#if BITRATE == 1200
#if BITRATE == 300
#define SIGNAL_TRANSITIONED(bits) DUAL_XOR((bits), (bits) >> 2)
#elif BITRATE == 1200
#if CONFIG_ADC_SAMPLERATE == 19200
#define SIGNAL_TRANSITIONED(bits) QUAD_XOR((bits), (bits) >> 4)
#elif CONFIG_ADC_SAMPLERATE == 9600
@ -81,7 +86,9 @@ inline static uint8_t sinSample(uint16_t i) {
// TODO: Test which target is best in real world
// For 1200, this seems a little better
#if BITRATE == 1200
#if BITRATE == 300
#define PHASE_THRESHOLD (PHASE_MAX / 2)
#elif BITRATE == 1200
#if CONFIG_ADC_SAMPLERATE == 19200
#define PHASE_THRESHOLD (PHASE_MAX / 2)+3*PHASE_BITS // Target transition point of our phase window
#elif CONFIG_ADC_SAMPLERATE == 9600
@ -158,14 +165,11 @@ typedef struct Afsk
// Demodulation values
FIFOBuffer delayFifo; // Delayed FIFO for frequency discrimination
#if BITRATE == 1200
// TODO: Clean this up
#if CONFIG_ADC_SAMPLERATE == 19200
int8_t delayBuf[ADC_SAMPLESPERBIT / 2 + 1]; // Actual data storage for said FIFO
#elif CONFIG_ADC_SAMPLERATE == 9600
int8_t delayBuf[ADC_SAMPLESPERBIT / 2 + 1]; // Actual data storage for said FIFO
#endif
#elif BITRATE == 2400
int8_t delayBuf[7 + 1]; // Actual data storage for said FIFO
int8_t delayBuf[7 + 1];
#elif BITRATE == 300
int8_t delayBuf[ADC_SAMPLESPERBIT / 2 + 1];
#endif
FIFOBuffer rxFifo; // FIFO for received data
@ -177,9 +181,7 @@ typedef struct Afsk
#if ADC_SAMPLESPERBIT < 17
uint16_t sampledBits; // Bits sampled by the demodulator (at ADC speed)
#else
// TODO: Enable error and set up correct size buffers
uint16_t sampledBits;
//#error Not enough space in sampledBits variable!
#error Not enough space in sampledBits variable!
#endif
int16_t currentPhase; // Current phase of the demodulator
uint8_t actualBits; // Actual found bits at correct bitrate