Interpolation: Narrower filter, normalize RMS.

src/apps/leandvbtx.cc

@@ -0,0 +1,169 @@
+// leandvbtx.cc copyright (c) 2016-2017 pabr@pabr.org
+// http://www.pabr.org/radio/leandvb
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <math.h>
+
+#include "leansdr/framework.h"
+#include "leansdr/generic.h"
+#include "leansdr/dsp.h"
+#include "leansdr/sdr.h"
+#include "leansdr/dvb.h"
+#include "leansdr/rs.h"
+#include "leansdr/filtergen.h"
+
+using namespace leansdr;
+
+template<typename T>
+struct interpolator : runnable {
+  unsigned int d;
+
+  interpolator(scheduler *sch, int _d, pipebuf<T> &_in, pipebuf<T> &_out)
+    : runnable(sch, "interpolator"),
+      d(_d),
+      in(_in), out(_out, d) { }
+  void run() {
+    unsigned long count = min(in.readable(), out.writable()/d);
+    T *pin=in.rd(), *pend=pin+count, *pout=out.wr();
+    for ( ; pin<pend; ++pin ) {
+      *pout++ = *pin;
+      for ( int skip=d-1; skip--; ) *pout++ = 0;
+    }
+    in.read(count);
+    out.written(count*d);
+  }
+private:
+  pipereader<T> in;
+  pipewriter<T> out;
+};
+
+struct config {
+  int interp;
+  int decim;
+  config()
+    : interp(2), decim(1)
+  { }
+};
+    
+void run(config &cfg) {
+  scheduler sch;
+
+  unsigned long BUF_PACKETS = 12;  // TBD Reduce copying
+  unsigned long BUF_BYTES = SIZE_RSPACKET*12;
+  unsigned long BUF_SYMBOLS = BUF_BYTES*8;
+  unsigned long BUF_BASEBAND = 4096;
+
+  // TS PACKETS ON STDIN
+
+  pipebuf<tspacket> p_tspackets(&sch, "TS packets", BUF_PACKETS);
+  file_reader<tspacket> r_stdin(&sch, 0, p_tspackets);
+
+  // RANDOMIZER
+
+  pipebuf<tspacket> p_rtspackets(&sch, "rand TS packets", BUF_PACKETS);
+  randomizer r_rand(&sch, p_tspackets, p_rtspackets);
+
+  // RS-ENCODER
+
+  pipebuf< rspacket<u8> > p_rspackets(&sch, "RS-enc packets", BUF_PACKETS);
+  rs_encoder r_rsenc(&sch, p_rtspackets, p_rspackets);
+
+  // PACKETS TO BYTES
+
+  pipebuf<u8> p_mpegbytes(&sch, "mpegbytes", BUF_BYTES);
+  interleaver r_inter(&sch, p_rspackets, p_mpegbytes);
+
+  // CONVOLUTIONAL CODER
+
+  pipebuf<u8> p_symbols(&sch, "symbols", BUF_SYMBOLS);
+  dvb_convol r_convol(&sch, p_mpegbytes, p_symbols);
+
+  // IQ MAPPER
+
+  pipebuf<cf32> p_iqsymbols(&sch, "IQ symbols", BUF_SYMBOLS);
+  cstln_transmitter<f32,0> r_mod(&sch, p_symbols, p_iqsymbols);
+  cstln_lut<256> qpsk(cstln_lut<256>::QPSK);
+  r_mod.cstln = &qpsk;
+
+  // RESAMPLER
+
+  if ( sch.verbose )
+    fprintf(stderr, "Resampling rate: %d/%d\n", cfg.interp, cfg.decim);
+  pipebuf<cf32> p_interp(&sch, "interpolated", BUF_BASEBAND);
+  float Fcut = 0.5 * (1.0) / cfg.interp;
+  int order = cfg.interp*10;
+  order = ((order+1)/2) * 2;
+  float *coeffs;
+  int ncoeffs = filtergen::lowpass(order, Fcut, &coeffs);
+  filtergen::normalize_power(ncoeffs, coeffs, sqrtf(cfg.interp));
+#if 0
+  fprintf(stderr, "COEFFS[%d]=", ncoeffs);
+  for ( int i=0; i<ncoeffs; ++i ) fprintf(stderr, " %f", coeffs[i]);
+  fprintf(stderr, "\n");
+#endif
+  fir_resampler<cf32,float>
+    r_resampler(&sch, ncoeffs, coeffs,
+		p_iqsymbols, p_interp, cfg.interp, 1);
+
+  pipebuf<cf32> p_resampled(&sch, "resampled", BUF_BASEBAND);
+  decimator<cf32> r_decim(&sch, cfg.decim, p_interp, p_resampled);
+
+#if 0
+  // SS ESTIMATOR
+
+  pipebuf<f32> p_ss(&sch, "ss", BUF_BASEBAND);
+  pipebuf<f32> p_ampmin(&sch, "ampmin", BUF_BASEBAND);
+  pipebuf<f32> p_ampmax(&sch, "ampmax", BUF_BASEBAND);
+  ss_amp_estimator<f32> r_ssest(&sch, p_resampled, p_ss, p_ampmin, p_ampmax);
+  r_ssest.window_size = 4096;
+  r_ssest.decimation = 4096 * 256;
+  file_printer<f32> r_print_ss(&sch, "TXSS %f\n", p_ss, 2);
+  file_printer<f32> r_print_ampmin(&sch, "TXAMPMIN %f\n", p_ampmin, 2);
+  file_printer<f32> r_print_ampmax(&sch, "TXAMPMAX %f\n", p_ampmax, 2);
+#endif
+
+  // IQ ON STDOUT
+
+  file_writer<cf32> r_stdout(&sch, p_resampled, 1);
+
+  sch.run();
+  sch.shutdown();
+  if ( sch.verbose ) sch.dump();
+}
+
+// Command-line
+
+void usage(const char *name, FILE *f, int c) {
+  fprintf(f, "Usage: %s [options]  < TS  > IQ\n", name);
+  fprintf(f, "Modulate MPEG packets into a DVB-S baseband signal\n");
+  fprintf(f, "Output float complex samples\n");
+  fprintf
+    (f, "\nOptions:"
+     "  -f INTERP[/DECIM]        Samples per symbols (default: 2)\n"
+     );
+  exit(c);
+}
+
+int main(int argc, char *argv[]) {
+  config cfg;
+
+  for ( int i=1; i<argc; ++i ) {
+    if      ( ! strcmp(argv[i], "-h") )
+      usage(argv[0], stdout, 0);
+    else if ( ! strcmp(argv[i], "-f") && i+1<argc ) {
+      ++i;
+      cfg.decim = 1;
+      if ( sscanf(argv[i], "%d/%d", &cfg.interp, &cfg.decim) < 1 )
+	usage(argv[0], stderr, 1);
+    }
+    else 
+      usage(argv[0], stderr, 1);
+  }
+
+  run(cfg);
+
+  return 0;
+}