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set default and optional 'channel' width for freq est limits, to avoid nearby strong signals

master
David Rowe 2020-08-09 12:55:58 +09:30
parent c882b32d1c
commit 8f4fc98b2b
1 changed files with 17 additions and 11 deletions
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24
src/rtl_fsk.c
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@ -55,6 +55,7 @@
#define DEFAULT_SYMBOL_RATE 10000 /* symbols/s */ #define DEFAULT_SYMBOL_RATE 10000 /* symbols/s */
#define DEFAULT_M 2 /* 2FSK */ #define DEFAULT_M 2 /* 2FSK */
#define NDFT 256 /* number of DFT points on dashboard */ #define NDFT 256 /* number of DFT points on dashboard */
#define DEFAULT_CHANNEL_WIDTH 25000 /* 25 kHz channel for freq est */
static int do_exit = 0; static int do_exit = 0;
static uint32_t bytes_to_read = 0; static uint32_t bytes_to_read = 0;
@ -72,6 +73,8 @@ static uint32_t sample_counter;
static uint32_t samp_rate = DEFAULT_SAMPLE_RATE; static uint32_t samp_rate = DEFAULT_SAMPLE_RATE;
static float norm_rx_timing_log[NORM_RX_TIMING_LOG_SZ]; static float norm_rx_timing_log[NORM_RX_TIMING_LOG_SZ];
static uint32_t norm_rx_timing_log_index = 0; static uint32_t norm_rx_timing_log_index = 0;
static int fsk_lower = 0;
static int fsk_upper = 0;
void usage(void) void usage(void)
{ {
@ -213,6 +216,8 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx)
/* FSK tone freq estimates */ /* FSK tone freq estimates */
snprintf(buf1, BUF_SZ, ", \"fsk_lower_Hz\":%d, \"fsk_upper_Hz\":%d",
fsk_lower, fsk_upper); strncat(buf, buf1, BUF_SZ);
if (fsk->freq_est_type) if (fsk->freq_est_type)
f_est = fsk->f2_est; f_est = fsk->f2_est;
else else
@ -270,8 +275,9 @@ int main(int argc, char **argv)
uint32_t frequency = 100000000; uint32_t frequency = 100000000;
int Rs = DEFAULT_SYMBOL_RATE; int Rs = DEFAULT_SYMBOL_RATE;
int M = DEFAULT_M; int M = DEFAULT_M;
int channel_width = DEFAULT_CHANNEL_WIDTH;
while ((opt = getopt(argc, argv, "d:f:g:s:b:n:p:S:u:r:m:")) != -1) { while ((opt = getopt(argc, argv, "d:f:g:s:b:n:p:S:u:r:m:c:M:R:")) != -1) {
switch (opt) { switch (opt) {
case 'd': case 'd':
dev_index = verbose_device_search(optarg); dev_index = verbose_device_search(optarg);
@ -295,9 +301,11 @@ int main(int argc, char **argv)
case 'n': case 'n':
bytes_to_read = (uint32_t)atof(optarg) * 2; bytes_to_read = (uint32_t)atof(optarg) * 2;
break; break;
case 'R':
case 'r': case 'r':
Rs = atoi(optarg); Rs = atoi(optarg);
break; break;
case 'M':
case 'm': case 'm':
M = atoi(optarg); M = atoi(optarg);
break; break;
@ -308,11 +316,10 @@ int main(int argc, char **argv)
dashboard = 1; dashboard = 1;
strcpy(hostname, optarg); strcpy(hostname, optarg);
break; break;
case 'M':
M = atoi(optarg); M = atoi(optarg);
break; break;
case 'R': case 'c':
Rs = atoi(optarg); channel_width = atoi(optarg);
break; break;
default: default:
usage(); usage();
@ -425,16 +432,15 @@ int main(int argc, char **argv)
} }
{ {
/* TODO: make some of these command line options */
int P = samp_rate/Rs; int P = samp_rate/Rs;
fsk = fsk_create_hbr(samp_rate,Rs,M,P,FSK_DEFAULT_NSYM,FSK_NONE,100); fsk = fsk_create_hbr(samp_rate,Rs,M,P,FSK_DEFAULT_NSYM,FSK_NONE,100);
fprintf(stderr,"FSK Demod Rs: %3.1f kHz M: %d P: %d Ndft: %d\n", (float)Rs/1000, M, P, fsk->Ndft); fprintf(stderr,"FSK Demod Rs: %3.1f kHz M: %d P: %d Ndft: %d\n", (float)Rs/1000, M, P, fsk->Ndft);
} }
{ {
/* TODO: fsk_lower might need some adjustment, so we avoid the RTLSDR DC line. We really need a GUI /* set minimum "channel" for freq est */
plot of the spectrum and tone estimates to observe what's going on */ fsk_lower = 0;
int fsk_lower = 0; fsk_upper = 4*Rs;
int fsk_upper = samp_rate/2; if (fsk_upper < channel_width) fsk_upper = channel_width;
fprintf(stderr,"Setting estimator limits to %d to %d Hz.\n", fsk_lower, fsk_upper); fprintf(stderr,"Setting estimator limits to %d to %d Hz.\n", fsk_lower, fsk_upper);
fsk_set_freq_est_limits(fsk,fsk_lower,fsk_upper); fsk_set_freq_est_limits(fsk,fsk_lower,fsk_upper);
} }