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/* -*- c++ -*- */
/*
* Copyright 2002 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 2, 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.
*/
#include <GrAtscBitTimingLoop3.h>
#include <cmath>
#include <cstdio>
#include <assert.h>
using std::abs;
static const int NOUTPUTS = 2;
GrAtscBitTimingLoop3::GrAtscBitTimingLoop3 (double ratio_of_rx_clock_to_symbol_freq)
: VrDecimatingSigProc<float,float> (NOUTPUTS, (int) rint (ratio_of_rx_clock_to_symbol_freq)),
d_interp (ratio_of_rx_clock_to_symbol_freq), d_next_input(0),
d_rx_clock_to_symbol_freq (ratio_of_rx_clock_to_symbol_freq)
{
assert (ratio_of_rx_clock_to_symbol_freq >= 1.8); // sanity check
history = 1500; // spare input samples in case we need them.
}
//
// We are nominally a 2x decimator, but our actual rate varies slightly
// depending on the difference between the transmitter and receiver
// sampling clocks. Hence, we need to compute our input ranges
// explictly.
int
GrAtscBitTimingLoop3::forecast(VrSampleRange output,
VrSampleRange inputs[]) {
assert (numberInputs == 1);
/* dec:1 ratio with history */
inputs[0].index = d_next_input;
inputs[0].size =
((unsigned long) (output.size * d_rx_clock_to_symbol_freq) + history - 1);
return 0;
}
int
GrAtscBitTimingLoop3::work (VrSampleRange output, void *ao[],
VrSampleRange inputs[], void *ai[])
{
iType *in = ((iType **)ai)[0];
oDataType *out_sample = ((oDataType **)ao)[0];
oTagType *out_tag = ((oTagType **) ao)[1];
// Force in-order computation of output stream.
// This is required because of our slightly variable decimation factor
sync (output.index);
// We are tasked with producing output.size output samples.
// We will consume approximately 2 * output.size input samples.
int si = 0; // source index
unsigned int k; // output index
float interp_sample;
int symbol_index;
double timing_adjustment = 0;
bool seg_locked;
oTagType tag;
memset (&tag, 0, sizeof (tag));
for (k = 0; k < output.size; k++){
if (!d_interp.update (in, inputs[0].size, &si, timing_adjustment, &interp_sample)){
fprintf (stderr, "GrAtscBitTimingLoop3: ran short on data...\n");
break;
}
d_sssr.update (interp_sample, &seg_locked, &symbol_index, &timing_adjustment);
out_sample[k] = interp_sample;
tag.valid = seg_locked;
tag.symbol_num = symbol_index;
out_tag[k] = tag;
}
d_next_input += si; // update next_input so forecast can get us what we need
return k;
}
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