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authorJohnathan Corgan <johnathan@corganlabs.com>2014-07-21 14:38:14 -0700
committerJohnathan Corgan <johnathan@corganlabs.com>2014-07-21 14:38:14 -0700
commit2ece28b3fea5b27baa6a6858e7645467d75cbd11 (patch)
treeb551a463d785aa4346442cd45ea7aaca73feaaa6 /gr-dtv/lib/atsc/atsc_sync_impl.cc
parentdbbc0687b7323c86eb2b1c2d7524ff212bbd64d8 (diff)
dtv: move ATSC blocks into lib/atsc
Diffstat (limited to 'gr-dtv/lib/atsc/atsc_sync_impl.cc')
-rw-r--r--gr-dtv/lib/atsc/atsc_sync_impl.cc196
1 files changed, 196 insertions, 0 deletions
diff --git a/gr-dtv/lib/atsc/atsc_sync_impl.cc b/gr-dtv/lib/atsc/atsc_sync_impl.cc
new file mode 100644
index 0000000000..ec46d6b8d1
--- /dev/null
+++ b/gr-dtv/lib/atsc/atsc_sync_impl.cc
@@ -0,0 +1,196 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2014 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * GNU Radio is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3, or (at your option)
+ * any later version.
+ *
+ * GNU Radio is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Radio; see the file COPYING. If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "atsc_sync_impl.h"
+#include "atsc_types.h"
+#include <gnuradio/io_signature.h>
+
+namespace gr {
+ namespace dtv {
+
+ atsc_sync::sptr
+ atsc_sync::make(float rate)
+ {
+ return gnuradio::get_initial_sptr
+ (new atsc_sync_impl(rate));
+ }
+
+ atsc_sync_impl::atsc_sync_impl(float rate)
+ : gr::block("dtv_atsc_sync",
+ io_signature::make(1, 1, sizeof(float)),
+ io_signature::make(1, 1, sizeof(atsc_soft_data_segment))),
+ d_next_input(0), d_rx_clock_to_symbol_freq(rate/ATSC_SYMBOL_RATE),
+ d_si(0)
+ {
+ d_loop.set_taps(LOOP_FILTER_TAP);
+ reset();
+ }
+
+ void
+ atsc_sync_impl::reset()
+ {
+ d_w = d_rx_clock_to_symbol_freq;
+ d_mu = 0.5;
+
+ for (int i = 0; i < ATSC_DATA_SEGMENT_LENGTH; i++)
+ sample_mem[i] = 0;
+
+ d_timing_adjust = 0;
+ d_counter = 0;
+ d_symbol_index = 0;
+ d_seg_locked = false;
+
+ d_sr = 0;
+
+ for (int i = 0; i < ATSC_DATA_SEGMENT_LENGTH; i++)
+ d_integrator[i] = SSI_MIN;
+ }
+
+ atsc_sync_impl::~atsc_sync_impl()
+ {
+ }
+
+ void
+ atsc_sync_impl::forecast(int noutput_items,
+ gr_vector_int &ninput_items_required)
+ {
+ unsigned ninputs = ninput_items_required.size();
+ for (unsigned i = 0; i < ninputs; i++)
+ ninput_items_required[i] = static_cast<int>(noutput_items * d_rx_clock_to_symbol_freq * ATSC_DATA_SEGMENT_LENGTH) + 1500 - 1;
+ }
+
+ int
+ atsc_sync_impl::general_work(int noutput_items,
+ gr_vector_int &ninput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items)
+ {
+ const float *in = (const float *) input_items[0];
+ atsc_soft_data_segment *soft_data_segment_out = (atsc_soft_data_segment *) output_items[0];
+
+ float interp_sample;
+
+ // amount actually consumed
+ d_si = 0;
+
+ for (output_produced = 0; output_produced < noutput_items && (d_si + (int)d_interp.ntaps()) < ninput_items[0];) {
+ // First we interpolate a sample from input to work with
+ interp_sample = d_interp.interpolate(&in[d_si], d_mu);
+
+ // Apply our timing adjustment slowly over several samples
+ d_mu += ADJUSTMENT_GAIN * 1e3 * d_timing_adjust;
+
+ double s = d_mu + d_w;
+ double float_incr = floor(s);
+ d_mu = s - float_incr;
+ d_incr = (int)float_incr;
+
+ assert (d_incr >= 1 && d_incr <= 3);
+ d_si += d_incr;
+
+ // Remember the sample at this count position
+ sample_mem[d_counter] = interp_sample;
+
+ // Is the sample positive or negative?
+ int bit = (interp_sample < 0 ? 0 : 1);
+
+ // Put the sign bit into our shift register
+ d_sr = ((bit & 1) << 3) | (d_sr >> 1);
+
+ // When +,-,-,+ (0x9, 1001) samples show up we have likely found a segment
+ // sync, it is more likely the segment sync will show up at about the same
+ // spot every ATSC_DATA_SEGMENT_LENGTH samples so we add some weight
+ // to this spot every pass to prevent random +,-,-,+ symbols from
+ // confusing our synchronizer
+ d_integrator[d_counter] += ((d_sr == 0x9) ? +2 : -1);
+ if(d_integrator[d_counter] < SSI_MIN) d_integrator[d_counter] = SSI_MIN;
+ if(d_integrator[d_counter] > SSI_MAX) d_integrator[d_counter] = SSI_MAX;
+
+ d_symbol_index++;
+ if( d_symbol_index >= ATSC_DATA_SEGMENT_LENGTH )
+ d_symbol_index = 0;
+
+ d_counter++;
+ if( d_counter >= ATSC_DATA_SEGMENT_LENGTH ) { // counter just wrapped...
+ int best_correlation_value = d_integrator[0];
+ int best_correlation_index = 0;
+
+ for(int i = 1; i < ATSC_DATA_SEGMENT_LENGTH; i++)
+ if (d_integrator[i] > best_correlation_value) {
+ best_correlation_value = d_integrator[i];
+ best_correlation_index = i;
+ }
+
+ d_seg_locked = best_correlation_value >= MIN_SEG_LOCK_CORRELATION_VALUE;
+
+ // the coefficients are -1,-1,+1,+1
+ //d_timing_adjust = sample_mem[best_correlation_index - 3] +
+ // sample_mem[best_correlation_index - 2] -
+ // sample_mem[best_correlation_index - 1] -
+ // sample_mem[best_correlation_index];
+
+ //printf( "d_timing_adjust = %f\n", d_timing_adjust );
+
+ int corr_count = best_correlation_index;
+
+ d_timing_adjust = -sample_mem[corr_count--];
+ if( corr_count < 0 ) corr_count = ATSC_DATA_SEGMENT_LENGTH - 1;
+ d_timing_adjust -= sample_mem[corr_count--];
+ if( corr_count < 0 ) corr_count = ATSC_DATA_SEGMENT_LENGTH - 1;
+ d_timing_adjust += sample_mem[corr_count--];
+ if( corr_count < 0 ) corr_count = ATSC_DATA_SEGMENT_LENGTH - 1;
+ d_timing_adjust += sample_mem[corr_count--];
+
+ d_symbol_index = SYMBOL_INDEX_OFFSET - 1 - best_correlation_index;
+ if (d_symbol_index < 0)
+ d_symbol_index += ATSC_DATA_SEGMENT_LENGTH;
+
+ d_counter = 0;
+ }
+
+ // If we are locked we can start filling and producing data packets
+ // Due to the way we lock the first data packet will almost always be
+ // half full, this is OK becouse the fs_checker will not let packets though
+ // untill a non-corrupted field packet is found
+ if( d_seg_locked ) {
+ data_mem[d_symbol_index] = interp_sample;
+
+ if( d_symbol_index >= (ATSC_DATA_SEGMENT_LENGTH - 1) )
+ {
+ for( int i = 0; i < ATSC_DATA_SEGMENT_LENGTH; i++ )
+ soft_data_segment_out[output_produced].data[i] = data_mem[i];
+ output_produced++;
+ }
+ }
+ }
+
+ consume_each(d_si);
+ return output_produced;
+
+ }
+
+ } /* namespace dtv */
+} /* namespace gr */
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