diff options
Diffstat (limited to 'gr-noaa/lib/noaa_hrpt_sync_cc.cc')
| -rw-r--r-- | gr-noaa/lib/noaa_hrpt_sync_cc.cc | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/gr-noaa/lib/noaa_hrpt_sync_cc.cc b/gr-noaa/lib/noaa_hrpt_sync_cc.cc index 47858d758..46cc277bd 100644 --- a/gr-noaa/lib/noaa_hrpt_sync_cc.cc +++ b/gr-noaa/lib/noaa_hrpt_sync_cc.cc @@ -27,6 +27,11 @@ #include <noaa_hrpt_sync_cc.h> #include <gr_io_signature.h> +inline int signum(float f) +{ + return f >= 0.0 ? 1 : -1; +} + noaa_hrpt_sync_cc_sptr noaa_make_hrpt_sync_cc(float alpha, float beta, float sps, float max_offset) { @@ -37,8 +42,10 @@ noaa_hrpt_sync_cc::noaa_hrpt_sync_cc(float alpha, float beta, float sps, float m : gr_block("noaa_hrpt_sync_cc", gr_make_io_signature(1, 1, sizeof(gr_complex)), gr_make_io_signature(1, 1, sizeof(gr_complex))), - d_alpha(alpha), d_beta(beta), d_sps(sps), d_max_offset(max_offset), - d_phase(0.0), d_freq(0.0) + d_alpha(alpha), d_beta(beta), + d_sps(sps), d_max_offset(max_offset), + d_phase(0.0), d_freq(1.0/sps), + d_last_sign(1) { } @@ -54,7 +61,25 @@ noaa_hrpt_sync_cc::general_work(int noutput_items, int i = 0, j = 0; while (i < ninputs && j < noutput_items) { - out[j++] = in[i++]; + float sample = in[i++].imag(); + int sign = signum(sample); + d_phase += d_freq; + + // Train on zero crossings in center region of symbol + if (sign != d_last_sign) { + if (d_phase > 0.25 && d_phase < 0.75) { + float phase_err = d_phase-0.5; + d_phase -= phase_err*d_alpha; // 1st order phase adjustment + d_freq -= phase_err*d_beta; // 2nd order frequency adjustment + } + + d_last_sign = sign; + } + + if (d_phase > 1.0) { + out[j++] = in[i]; + d_phase -= 1.0; + } } consume_each(i); |