3 * Copyright 2006 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2, or (at your option)
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
27 #include <atsc_bit_timing_loop.h>
28 #include <gr_io_signature.h>
29 #include <atsc_consts.h>
31 float input_rate = 20e6;
32 double ratio_of_rx_clock_to_symbol_freq = input_rate / ATSC_SYMBOL_RATE;
35 atsc_bit_timing_loop_sptr
36 atsc_make_bit_timing_loop()
38 return atsc_bit_timing_loop_sptr(new atsc_bit_timing_loop());
42 atsc_bit_timing_loop::atsc_bit_timing_loop()
43 : gr_block("atsc_bit_timing_loop",
44 gr_make_io_signature(1, 1, sizeof(float)),
45 gr_make_io_signature(2, 2, sizeof(float))),
46 d_interp(ratio_of_rx_clock_to_symbol_freq), d_next_input(0),
47 d_rx_clock_to_symbol_freq (ratio_of_rx_clock_to_symbol_freq)
53 atsc_bit_timing_loop::forecast (int noutput_items, gr_vector_int &ninput_items_required)
55 unsigned ninputs = ninput_items_required.size();
56 for (unsigned i = 0; i < ninputs; i++)
57 ninput_items_required[i] = noutput_items * d_rx_clock_to_symbol_freq + 1500 - 1;
59 inputs0_size = noutput_items * d_rx_clock_to_symbol_freq + 1500 - 1;
60 inputs0_index = d_next_input;
64 atsc_bit_timing_loop::general_work (int noutput_items,
65 gr_vector_int &ninput_items,
66 gr_vector_const_void_star &input_items,
67 gr_vector_void_star &output_items)
69 int r = work (noutput_items, input_items, output_items);
71 consume_each (r * d_rx_clock_to_symbol_freq);
77 atsc_bit_timing_loop::work (int noutput_items,
78 gr_vector_const_void_star &input_items,
79 gr_vector_void_star &output_items)
81 const float *in = (const float *) input_items[0];
82 float *out_sample = (float *) output_items[0];
83 atsc::syminfo *out_tag = (atsc::syminfo *) output_items[1];
85 assert(sizeof(float) == sizeof(atsc::syminfo));
87 // We are tasked with producing output.size output samples.
88 // We will consume approximately 2 * output.size input samples.
90 int si = 0; // source index
91 unsigned int k; // output index
95 double timing_adjustment = 0;
99 memset (&tag, 0, sizeof (tag));
102 for (k = 0; k < noutput_items; k++){
103 if (!d_interp.update (in, inputs0_size, &si, timing_adjustment, &interp_sample)){
104 fprintf (stderr, "GrAtscBitTimingLoop3: ran short on data...\n");
108 d_sssr.update (interp_sample, &seg_locked, &symbol_index, &timing_adjustment);
109 out_sample[k] = interp_sample;
110 tag.valid = seg_locked;
111 tag.symbol_num = symbol_index;
116 d_next_input += si; // update next_input so forecast can get us what we need