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/* -*- c++ -*- */
/*
* Copyright 2004 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 <gsm_receiver_cf.h>
#include <gr_io_signature.h>
#include <gr_math.h>
#include <gsm_constants.h>
#include <Assert.h>
gsm_receiver_cf_sptr
gsm_make_receiver_cf(int osr)
{
return gsm_receiver_cf_sptr(new gsm_receiver_cf(osr));
}
static const int MIN_IN = 1; // mininum number of input streams
static const int MAX_IN = 1; // maximum number of input streams
static const int MIN_OUT = 0; // minimum number of output streams
static const int MAX_OUT = 1; // maximum number of output streams
/*
* The private constructor
*/
gsm_receiver_cf::gsm_receiver_cf(int osr)
: gr_block("gsm_receiver",
gr_make_io_signature(MIN_IN, MAX_IN, sizeof(gr_complex)),
gr_make_io_signature(MIN_OUT, MAX_OUT, 142 * sizeof(float))),
d_counter(0)
{
}
/*
* Virtual destructor.
*/
gsm_receiver_cf::~gsm_receiver_cf()
{
}
void gsm_receiver_cf::forecast(int noutput_items, gr_vector_int &ninput_items_required)
{
ninput_items_required[0] = noutput_items * TS_BITS; //TODO include oversampling ratio here
}
int
gsm_receiver_cf::general_work(int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const gr_complex *in = (const gr_complex *) input_items[0];
float *out = (float *) output_items[0];
// DCOUT(ninput_items[0]);
// DCOUT(noutput_items);
d_return = 0; //!
int start_pos = find_fcch_burst(in, ninput_items[0]);
for (int i = 0; i < TS_BITS; i++) {
out[i] = d_phase_diff_buffer[i+start_pos-USEFUL_BITS];
}
consume_each(start_pos);
d_counter += start_pos;
return d_return;
}
int gsm_receiver_cf::find_fcch_burst(const gr_complex *in, const int nitems)
{
for (int i = 0; (i < nitems - 1) && (i < BUFFER_SIZE); i++) {
gr_complex conjprod = in[i+1] * conj(in[i]);
float diff_angle = gr_fast_atan2f(imag(conjprod), real(conjprod));
d_phase_diff_buffer[i] = diff_angle;
}
int hit_count = 0;
int miss_count = 0;
int start_pos = -1;
d_return = 0;//!
for (int i = 0; ; i++) {
if (i > nitems - USEFUL_BITS - 1) {
start_pos = nitems - USEFUL_BITS - 1;
break;
}
if (d_phase_diff_buffer[i] > 0) {
if (! hit_count) {
start_pos = i+USEFUL_BITS;
}
hit_count++;
} else if (hit_count >= FCCH_HITS_NEEDED) {
DCOUT("znalezione fcch na pozycji" << d_counter+start_pos-USEFUL_BITS);
d_return = 1;//!
break;
} else if (++miss_count > FCCH_MAX_MISSES) {
start_pos = -1;
hit_count = miss_count = 0;
}
}
/*
//Do we have a match?
if (start_pos >= 0) {
//Is it within range? (we know it's long enough then too)
if (start_pos < 2*MAX_CORR_DIST) {
d_burst_start = start_pos;
d_bbuf_pos = 0; //load buffer from start
return FCCH;
} else {
//TODO: don't shift a tiny amount
shift_burst(start_pos - MAX_CORR_DIST);
}
} else {
//Didn't find anything
d_burst_start = MAX_CORR_DIST;
d_bbuf_pos = 0; //load buffer from start
}
*/
//DCOUT("start_pos: " << start_pos);
return start_pos;
}
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