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coded up decimator, but not tested

master
David 2020-08-18 15:10:39 +09:30
parent bd6097365a
commit ec04e1601a
1 changed files with 129 additions and 23 deletions
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152
src/rtl_fsk.c
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@ -47,16 +47,23 @@
#include "fsk.h"
#include "libcsdr.h"
#define DEFAULT_SAMPLE_RATE 240000
/* rtlsdr ------------------------------------*/
#define DEFAULT_SAMPLE_RATE 1800000
#define DEFAULT_BUF_LENGTH (16 * 16384)
#define MINIMAL_BUF_LENGTH 512
#define MAXIMAL_BUF_LENGTH (256 * 16384)
#define BUF_SZ 8192
#define NORM_RX_TIMING_LOG_SZ 1024
/* fsk modem ----------------------------------*/
#define CSDR_BUFSIZE 1024
#define DEFAULT_MODEM_SAMPLE_RATE 40000 /* sample rate we run demod at */
#define DEFAULT_SYMBOL_RATE 10000 /* symbols/s */
#define DEFAULT_M 2 /* 2FSK */
#define NDFT 256 /* number of DFT points on dashboard */
#define DEFAULT_CHANNEL_WIDTH 25000 /* 25 kHz channel for freq est */
#define NORM_RX_TIMING_LOG_SZ 1024
static int do_exit = 0;
static uint32_t bytes_to_read = 0;
@ -70,6 +77,7 @@ static int dashboard = 0;
static int sockfd;
static struct sockaddr_in serveraddr;
static int portno = 8001;
static uint32_t sample_counter;
static uint32_t samp_rate = DEFAULT_SAMPLE_RATE;
static float norm_rx_timing_log[NORM_RX_TIMING_LOG_SZ];
@ -77,6 +85,17 @@ static uint32_t norm_rx_timing_log_index = 0;
static int fsk_lower = 0;
static int fsk_upper = 0;
static int csdr_factor;
static float csdr_in[CSDR_BUFSIZE*2];
static float csdr_out[CSDR_BUFSIZE*2];
static int csdr_nout, csdr_nin;
static int csdr_padded_taps_length;
static float *csdr_taps;
static COMP* modembuf;
static size_t nmodembuf = 0;
static size_t nmodembuf_max = 0;
void usage(void)
{
fprintf(stderr,
@ -130,11 +149,53 @@ static void udp_sendbuf(char buf[]) {
}
}
static void csdr_decimate_cc(float *out, float *in, int the_bufsize, float *taps, int taps_length, int factor, int *nout, int *next_nin) {
int output_size, input_skip;
output_size=fir_decimate_cc((complexf*)in, (complexf*)out, the_bufsize, factor, taps, taps_length);
input_skip=factor*output_size;
memmove((complexf*)in,((complexf*)in)+input_skip,(the_bufsize-input_skip)*sizeof(complexf));
*nout = output_size;
*next_nin = input_skip;
}
static float *csdr_init_decimate_cc(int factor, float transition_bw, window_t window, int *padded_taps_length) {
int taps_length;
float *taps;
int i;
fprintf(stderr,"fir_decimate_cc: factor = %d window = %s\n", factor, firdes_get_string_from_window(window));
taps_length = firdes_filter_len(transition_bw);
fprintf(stderr,"fir_decimate_cc: taps_length = %d\n",taps_length);
// allocate taps array
*padded_taps_length = taps_length;
#define NEON_ALIGNMENT (4*4*2)
#ifdef NEON_OPTS
errhead(); fprintf(stderr,"taps_length = %d\n", taps_length);
*padded_taps_length = taps_length+(NEON_ALIGNMENT/4)-1 - ((taps_length+(NEON_ALIGNMENT/4)-1)%(NEON_ALIGNMENT/4));
fprintf(stderr,"padded_taps_length = %d\n", *padded_taps_length);
taps = (float*) (float*)malloc((*padded_taps_length+NEON_ALIGNMENT)*sizeof(float));
fprintf(stderr,"taps = %x\n", taps);
taps = (float*)((((unsigned)taps)+NEON_ALIGNMENT-1) & ~(NEON_ALIGNMENT-1));
errhead(); fprintf(stderr,"NEON aligned taps = %x\n", taps);
for(i=0;i<*padded_taps_length-taps_length;i++) taps[taps_length+i]=0;
#else
taps = (float*)malloc(taps_length*sizeof(float));
#endif
firdes_lowpass_f(taps,taps_length, 0.5/(float)factor,window);
return taps;
}
static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx)
{
unsigned char *pout;
unsigned int i;
unsigned char bitbuf[fsk->Nbits];
COMP *pmodembuf;
int prev_fsk_nin;
if (ctx) {
if (do_exit)
@ -153,30 +214,51 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx)
}
*/
/* append to existing samples in rawbuf */
/* resample rawbuf to demod sample rate ------------------------------- */
memcpy(&rawbuf[nrawbuf],buf,len);
nrawbuf += len;
assert(nrawbuf < 2*out_block_size);
assert(nrawbuf < nrawbuf_max);
/* process as many samples in rawbuf as possible */
pout = rawbuf;
while(nrawbuf >= 2*fsk_nin(fsk)) {
COMP modbuf[fsk->N+fsk->Ts*2]; /* max nin value with timing slips */
/* complex unsigned 8 bit to float conversion */
for(i=0;i<fsk_nin(fsk);i++){
modbuf[i].real = ((float)pout[2*i]-127.0)/128.0;
modbuf[i].imag = ((float)pout[2*i+1]-127.0)/128.0;
pmodembuf = modembuf + nmodembuf;
while(nrawbuf >= 2*(size_t)csdr_nin) {
complexf *pcsdr_in = ((complexf*)csdr_in)+(CSDR_BUFSIZE-csdr_nin);
for(i=0;i<(uint32_t)csdr_nin;i++) {
pcsdr_in[i].i = ((float)pout[2*i]-127.0)/128.0;
pcsdr_in[i].q = ((float)pout[2*i+1]-127.0)/128.0;
}
pout += 2*fsk_nin(fsk);
nrawbuf -= 2*fsk_nin(fsk);
fsk_demod(fsk, bitbuf, modbuf);
csdr_decimate_cc((float*)pmodembuf, csdr_in, CSDR_BUFSIZE, csdr_taps, csdr_padded_taps_length, csdr_factor,
&csdr_nout, &csdr_nin);
/* place resampled signal in modem input buf */
pmodembuf += csdr_nout;
nmodembuf += csdr_nout;
assert(pmodem_buf < (modembuf + nmodembuf_max));
pout += 2*csdr_nin;
nrawbuf -= 2*csdr_nin;
assert(nrawbuf >= 0);
}
/* copy left over rawbuf samples to start for next time */
memmove(rawbuf,pout,nrawbuf);
/* when we have fsk_nin() samples run demod ----------------------------- */
pmodembuf = modembuf;
while(nmodembuf >= fsk_nin(fsk)) {
prev_fsk_nin = fsk_nin(fsk); /* fsk_nin gets updated in fsk_demod() */
fsk_demod(fsk, bitbuf, pmodembuf);
pmodembuf += 2*prev_fsk_nin;
nmodembuf -= 2*prev_fsk_nin;
assert(nmodembuf >= 0);
/* output demodulated bits */
if (fwrite(bitbuf, 1, fsk->Nbits, (FILE*)ctx) != (unsigned int)fsk->Nbits) {
fprintf(stderr, "Short write, bits lost, exiting!\n");
rtlsdr_cancel_async(dev);
}
if((FILE*)ctx == stdout) fflush((FILE*)ctx);
if (dashboard) {
/* update buffer of timing samples */
if (norm_rx_timing_log_index < NORM_RX_TIMING_LOG_SZ)
@ -250,8 +332,8 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx)
}
}
/* copy left over to start of buffer */
memmove(rawbuf,pout,nrawbuf);
/* copy left over modem saples to start of buffer */
memmove(modembuf,pmodembuf,nmodembuf*sizeof(COMP));
if (bytes_to_read > 0)
bytes_to_read -= len;
@ -346,12 +428,17 @@ int main(int argc, char **argv)
out_block_size = DEFAULT_BUF_LENGTH;
}
buffer = malloc(out_block_size * sizeof(uint8_t));
buffer = malloc(out_block_size * sizeof(uint8_t)); assert(buffer != NULL);
nrawbuf_max = 2 * out_block_size;
rawbuf = malloc(nrawbuf_max * sizeof(uint8_t));
rawbuf = malloc(nrawbuf_max * sizeof(uint8_t)); assert(rawbuf != NULL);
nrawbuf = 0;
/* create UDP socket for debug/status information */
assert((samp_rate % DEFAULT_MODEM_SAMPLE_RATE) == 0);
nmodembuf_max = nrawbuf_max*samp_rate/DEFAULT_MODEM_SAMPLE_RATE;
modembuf = (COMP*)malloc(nmodembuf_max * sizeof(COMP)); assert(modembuf != NULL);
/* create UDP socket for dashboard debug/status information ----------------------------- */
if (dashboard) {
struct hostent *server;
@ -432,11 +519,28 @@ int main(int argc, char **argv)
goto out;
}
}
/* Setup the CSDR Decimator -------------------------------------------------*/
{
// design decimating filter
float transition_bw = 0.05;
window_t window = WINDOW_DEFAULT;
csdr_factor = samp_rate/DEFAULT_MODEM_SAMPLE_RATE;
csdr_taps = csdr_init_decimate_cc(csdr_factor, transition_bw, window, &csdr_padded_taps_length);
assert(CSDR_BUFSIZE > padded_taps_length);
// first call to work out how many input samples needed (csdr_nin)
csdr_decimate_cc(csdr_out, csdr_in, CSDR_BUFSIZE, csdr_taps, csdr_padded_taps_length, csdr_factor, &csdr_nout, &csdr_nin);
}
/* Setup the FSK demod -------------------------------------------------*/
{
int P = samp_rate/Rs;
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);
int P = DEFAULT_MODEM_SAMPLE_RATE/Rs;
fsk = fsk_create_hbr(DEFAULT_MODEM_SAMPLE_RATE,Rs,M,P,FSK_DEFAULT_NSYM,FSK_NONE,100);
fprintf(stderr,"FSK Demod Fs: %d Rs: %3.1f kHz M: %d P: %d Ndft: %d\n", DEFAULT_MODEM_SAMPLE_RATE,
(float)Rs/1000, M, P, fsk->Ndft);
}
{
/* set minimum "channel" for freq est */
@ -447,6 +551,7 @@ int main(int argc, char **argv)
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);
}
/* Reset endpoint before we start reading from it (mandatory) */
verbose_reset_buffer(dev);
@ -495,6 +600,7 @@ int main(int argc, char **argv)
fsk_destroy(fsk);
free (buffer);
free (rawbuf);
free(modembuf);
out:
return r >= 0 ? r : -r;
}