From b3fb6cc35e7026246ce1d71d248fccefe230aab8 Mon Sep 17 00:00:00 2001 From: Mark Qvist Date: Sun, 26 Apr 2015 18:15:05 +0200 Subject: [PATCH] Implemented selectable data rates --- hardware/AFSK.c | 20 ++++++++++++++++++-- hardware/AFSK.h | 27 +++++++++++++++++---------- 2 files changed, 35 insertions(+), 12 deletions(-) diff --git a/hardware/AFSK.c b/hardware/AFSK.c index a4866ba..c8c5f90 100644 --- a/hardware/AFSK.c +++ b/hardware/AFSK.c @@ -340,8 +340,16 @@ void AFSK_adc_isr(Afsk *afsk, int8_t currentSample) { 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; #else - #error Unsupported bitrate! + #error Unsupported filter cutoff! #endif afsk->iirY[0] = afsk->iirY[1]; @@ -354,8 +362,16 @@ void AFSK_adc_isr(Afsk *afsk, int8_t currentSample) { 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 800Hz 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 800Hz chebyshev filter: + // afsk->iirY[1] = afsk->iirX[0] + afsk->iirX[1] + (afsk->iirY[0] * -0.0630669239); #else - #error Unsupported bitrate! + #error Unsupported filter cutoff! #endif diff --git a/hardware/AFSK.h b/hardware/AFSK.h index aab4823..aecce47 100644 --- a/hardware/AFSK.h +++ b/hardware/AFSK.h @@ -44,15 +44,20 @@ inline static uint8_t sinSample(uint16_t i) { #define CONFIG_AFSK_RXTIMEOUT 0 #define CONFIG_AFSK_PREAMBLE_LEN 150UL #define CONFIG_AFSK_TRAILER_LEN 50UL +#define BIT_STUFF_LEN 5 + #define SAMPLERATE 9600 -#define BITRATE 1600 +#define BITRATE 1200 + +#define SAMPLESPERBIT (SAMPLERATE / BITRATE) +#define PHASE_INC 1 // Nudge by an eigth of a sample each adjustment #if BITRATE == 960 #define FILTER_CUTOFF 600 - #define MARK_FREQ 1300 - #define SPACE_FREQ 2100 - #define PHASE_BITS 8 // How much to increment phase counter each sample -#if BITRATE == 1200 + #define MARK_FREQ 960 + #define SPACE_FREQ 1600 + #define PHASE_BITS 10 // How much to increment phase counter each sample +#elif BITRATE == 1200 #define FILTER_CUTOFF 600 #define MARK_FREQ 1200 #define SPACE_FREQ 2200 @@ -60,15 +65,17 @@ inline static uint8_t sinSample(uint16_t i) { #elif BITRATE == 1600 #define FILTER_CUTOFF 800 #define MARK_FREQ 1600 - #define SPACE_FREQ 2800 - #define PHASE_BITS 6 + #define SPACE_FREQ 2600 + #define PHASE_BITS 8 +#elif BITRATE == 2400 + #define FILTER_CUTOFF 1600 + #define MARK_FREQ 2400 + #define SPACE_FREQ 4200 + #define PHASE_BITS 4 #else #error Unsupported bitrate! #endif -#define SAMPLESPERBIT (SAMPLERATE / BITRATE) -#define BIT_STUFF_LEN 5 -#define PHASE_INC 1 // Nudge by an eigth of a sample each adjustment #define PHASE_MAX (SAMPLESPERBIT * PHASE_BITS) // Resolution of our phase counter = 64 #define PHASE_THRESHOLD (PHASE_MAX / 2) // Target transition point of our phase window