KB8PMY
/
NanoVNA
mirror of https://github.com/ttrftech/NanoVNA.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Add limited variable offset support, and constant sin_cos tables for various offset and ADC speed

Browse Source
pull/130/head
DiSlord 6 years ago
parent 018b9c7776
commit c322d5e3cb
1 changed files with 84 additions and 38 deletions
Show Stats Download Patch File Download Diff File

122
dsp.c
Unescape View File

@ -26,7 +26,23 @@ int16_t samp_buf[SAMPLE_LEN];
int16_t ref_buf[SAMPLE_LEN]; int16_t ref_buf[SAMPLE_LEN];
#endif #endif
#if 1 #ifdef USE_VARIABLE_OFFSET
int16_t sincos_tbl[AUDIO_SAMPLES_COUNT][2];
void generate_DSP_Table(int offset){
float audio_freq = AUDIO_ADC_FREQ;
// N = offset * AUDIO_SAMPLES_COUNT / audio_freq; should be integer
// AUDIO_SAMPLES_COUNT = N * audio_freq / offset; N - minimum integer value for get integer AUDIO_SAMPLES_COUNT
// Bandwidth on one step = audio_freq / AUDIO_SAMPLES_COUNT
float step = 2 * VNA_PI * offset / audio_freq;
float v = step/2;
for (int i=0; i<AUDIO_SAMPLES_COUNT; i++){
sincos_tbl[i][0] = sin(v)*32768.0 + 0.5;
sincos_tbl[i][1] = cos(v)*32768.0 + 0.5;
v+=step;
}
}
#elif FREQUENCY_OFFSET==5000*(AUDIO_ADC_FREQ/AUDIO_SAMPLES_COUNT/1000)
// static Table for 10kHz IF and 96kHz ADC (or 5kHz IF and 48kHz ADC) audio ADC
const int16_t sincos_tbl[48][2] = { const int16_t sincos_tbl[48][2] = {
{ 10533, 31029 }, { 27246, 18205 }, { 32698, -2143 }, { 24636, -21605 }, { 10533, 31029 }, { 27246, 18205 }, { 32698, -2143 }, { 24636, -21605 },
{ 6393, -32138 }, {-14493, -29389 }, {-29389, -14493 }, {-32138, 6393 }, { 6393, -32138 }, {-14493, -29389 }, {-29389, -14493 }, {-32138, 6393 },
@ -41,30 +57,50 @@ const int16_t sincos_tbl[48][2] = {
{ 32138, 6393 }, { 29389, -14493 }, { 14493, -29389 }, { -6393, -32138 }, { 32138, 6393 }, { 29389, -14493 }, { 14493, -29389 }, { -6393, -32138 },
{-24636, -21605 }, {-32698, -2143 }, {-27246, 18205 }, {-10533, 31029 } {-24636, -21605 }, {-32698, -2143 }, {-27246, 18205 }, {-10533, 31029 }
}; };
#elif FREQUENCY_OFFSET==4000*(AUDIO_ADC_FREQ/AUDIO_SAMPLES_COUNT/1000)
// static Table for 8kHz IF and 96kHz audio ADC (or 4kHz IF and 48kHz ADC) audio ADC
const int16_t sincos_tbl[48][2] = {
{ 4277, 32488}, { 19948, 25997}, { 30274, 12540}, { 32488, -4277},
{ 25997,-19948}, { 12540,-30274}, { -4277,-32488}, {-19948,-25997},
{-30274,-12540}, {-32488, 4277}, {-25997, 19948}, {-12540, 30274},
{ 4277, 32488}, { 19948, 25997}, { 30274, 12540}, { 32488, -4277},
{ 25997,-19948}, { 12540,-30274}, { -4277,-32488}, {-19948,-25997},
{-30274,-12540}, {-32488, 4277}, {-25997, 19948}, {-12540, 30274},
{ 4277, 32488}, { 19948, 25997}, { 30274, 12540}, { 32488, -4277},
{ 25997,-19948}, { 12540,-30274}, { -4277,-32488}, {-19948,-25997},
{-30274,-12540}, {-32488, 4277}, {-25997, 19948}, {-12540, 30274},
{ 4277, 32488}, { 19948, 25997}, { 30274, 12540}, { 32488, -4277},
{ 25997,-19948}, { 12540,-30274}, { -4277,-32488}, {-19948,-25997},
{-30274,-12540}, {-32488, 4277}, {-25997, 19948}, {-12540, 30274}
};
#elif FREQUENCY_OFFSET==3000*(AUDIO_ADC_FREQ/AUDIO_SAMPLES_COUNT/1000)
// static Table for 6kHz IF and 96kHz audio ADC (or 3kHz IF and 48kHz ADC) audio ADC
const int16_t sincos_tbl[48][2] = {
{ 3212, 32610}, { 15447, 28899}, { 25330, 20788}, { 31357, 9512},
{ 32610, -3212}, { 28899,-15447}, { 20788,-25330}, { 9512,-31357},
{ -3212,-32610}, {-15447,-28899}, {-25330,-20788}, {-31357, -9512},
{-32610, 3212}, {-28899, 15447}, {-20788, 25330}, { -9512, 31357},
{ 3212, 32610}, { 15447, 28899}, { 25330, 20788}, { 31357, 9512},
{ 32610, -3212}, { 28899,-15447}, { 20788,-25330}, { 9512,-31357},
{ -3212,-32610}, {-15447,-28899}, {-25330,-20788}, {-31357, -9512},
{-32610, 3212}, {-28899, 15447}, {-20788, 25330}, { -9512, 31357},
{ 3212, 32610}, { 15447, 28899}, { 25330, 20788}, { 31357, 9512},
{ 32610, -3212}, { 28899,-15447}, { 20788,-25330}, { 9512,-31357},
{ -3212,-32610}, {-15447,-28899}, {-25330,-20788}, {-31357, -9512},
{-32610, 3212}, {-28899, 15447}, {-20788, 25330}, { -9512, 31357}
};
#else #else
int16_t sincos_tbl[AUDIO_SAMPLES_COUNT][2]; #error "Need check/rebuild sin cos table for DAC"
void generate_DSP_Table(int offset){
float audio_freq = AUDIO_ADC_FREQ;
// N = offset * AUDIO_SAMPLES_COUNT / audio_freq; should be integer
// AUDIO_SAMPLES_COUNT = N * audio_freq / offset; N - minimum integer value for get integer AUDIO_SAMPLES_COUNT
// Bandwidth on one step = audio_freq / AUDIO_SAMPLES_COUNT
float step = 2 * VNA_PI * offset / audio_freq;
float v = step/2;
for (int i=0; i<AUDIO_SAMPLES_COUNT; i++){
sincos_tbl[i][0] = sin(v)*32768.0 + 0.5;
sincos_tbl[i][1] = cos(v)*32768.0 + 0.5;
v+=step;
}
}
#endif #endif
#if 1
// Define DSP accumulator value type
typedef float acc_t; typedef float acc_t;
typedef float measure_t;
acc_t acc_samp_s; acc_t acc_samp_s;
acc_t acc_samp_c; acc_t acc_samp_c;
acc_t acc_ref_s; acc_t acc_ref_s;
acc_t acc_ref_c; acc_t acc_ref_c;
#if 1
void void
dsp_process(int16_t *capture, size_t length) dsp_process(int16_t *capture, size_t length)
{ {
@ -95,16 +131,25 @@ dsp_process(int16_t *capture, size_t length)
} }
#else #else
// Define DSP accumulator value type
typedef int64_t acc_t;
typedef float measure_t;
acc_t acc_samp_s;
acc_t acc_samp_c;
acc_t acc_ref_s;
acc_t acc_ref_c;
// Cortex M4 DSP instruction use // Cortex M4 DSP instruction use
#include "dsp.h" #include "dsp.h"
void void
dsp_process(int16_t *capture, size_t length) dsp_process(int16_t *capture, size_t length)
{ {
uint32_t i = 0; uint32_t i = 0;
int64_t samp_s = 0; // int64_t samp_s = 0;
int64_t samp_c = 0; // int64_t samp_c = 0;
int64_t ref_s = 0; // int64_t ref_s = 0;
int64_t ref_c = 0; // int64_t ref_c = 0;
i=0;
do{ do{
int32_t sc = ((int32_t *)sincos_tbl)[i]; int32_t sc = ((int32_t *)sincos_tbl)[i];
int32_t sr = ((int32_t *)capture)[i]; int32_t sr = ((int32_t *)capture)[i];
@ -114,17 +159,18 @@ dsp_process(int16_t *capture, size_t length)
// ref_s = __smlabb(sr, sc, ref_s); // ref_s+= ref * sin // ref_s = __smlabb(sr, sc, ref_s); // ref_s+= ref * sin
// ref_c = __smlabt(sr, sc, ref_c); // ref_s+= ref * cos // ref_c = __smlabt(sr, sc, ref_c); // ref_s+= ref * cos
// int64_t acc DSP functions // int64_t acc DSP functions
samp_s= __smlaltb(samp_s, sr, sc ); // samp_s+= smp * sin acc_samp_s= __smlaltb(acc_samp_s, sr, sc ); // samp_s+= smp * sin
samp_c= __smlaltt(samp_c, sr, sc ); // samp_c+= smp * cos acc_samp_c= __smlaltt(acc_samp_c, sr, sc ); // samp_c+= smp * cos
ref_s = __smlalbb( ref_s, sr, sc ); // ref_s+= ref * sin acc_ref_s = __smlalbb( acc_ref_s, sr, sc ); // ref_s+= ref * sin
ref_c = __smlalbt( ref_c, sr, sc ); // ref_s+= ref * cos acc_ref_c = __smlalbt( acc_ref_c, sr, sc ); // ref_s+= ref * cos
i++; i++;
} while (i < length/2); } while (i < length/2);
// Accumulate result, for faster calc and prevent overflow reduce size to int32_t // Accumulate result, for faster calc and prevent overflow reduce size to int32_t
acc_samp_s+= (int32_t)(samp_s>>3); // acc_samp_s+= (int32_t)(samp_s>>4);
acc_samp_c+= (int32_t)(samp_c>>3); // acc_samp_c+= (int32_t)(samp_c>>4);
acc_ref_s += (int32_t)( ref_s>>3); // acc_ref_s += (int32_t)( ref_s>>4);
acc_ref_c += (int32_t)( ref_c>>3); // acc_ref_c += (int32_t)( ref_c>>4);
} }
#endif #endif
@ -134,19 +180,19 @@ calculate_gamma(float gamma[2])
#if 1 #if 1
// calculate reflection coeff. by samp divide by ref // calculate reflection coeff. by samp divide by ref
#if 0 #if 0
float rs = acc_ref_s; measure_t rs = acc_ref_s;
float rc = acc_ref_c; measure_t rc = acc_ref_c;
float rr = rs * rs + rc * rc; measure_t rr = rs * rs + rc * rc;
//rr = sqrtf(rr) * 1e8; //rr = sqrtf(rr) * 1e8;
float ss = acc_samp_s; measure_t ss = acc_samp_s;
float sc = acc_samp_c; measure_t sc = acc_samp_c;
gamma[0] = (sc * rc + ss * rs) / rr; gamma[0] = (sc * rc + ss * rs) / rr;
gamma[1] = (ss * rc - sc * rs) / rr; gamma[1] = (ss * rc - sc * rs) / rr;
#else #else
float rs_rc = (float) acc_ref_s / acc_ref_c; measure_t rs_rc = (measure_t) acc_ref_s / acc_ref_c;
float sc_rc = (float)acc_samp_c / acc_ref_c; measure_t sc_rc = (measure_t)acc_samp_c / acc_ref_c;
float ss_rc = (float)acc_samp_s / acc_ref_c; measure_t ss_rc = (measure_t)acc_samp_s / acc_ref_c;
float rr = rs_rc * rs_rc + 1.0; measure_t rr = rs_rc * rs_rc + 1.0;
gamma[0] = (sc_rc + ss_rc*rs_rc) / rr; gamma[0] = (sc_rc + ss_rc*rs_rc) / rr;
gamma[1] = (ss_rc - sc_rc*rs_rc) / rr; gamma[1] = (ss_rc - sc_rc*rs_rc) / rr;
#endif #endif

Write Preview
Loading…
Cancel
Save

Powered by TurnKey Linux.