GNU Radio 3.6.5.1 C++ API
digital_ofdm_sync_sc_cfb.h
Go to the documentation of this file.
1
/* -*- c++ -*- */
2
/* Copyright 2012 Free Software Foundation, Inc.
3
*
4
* This file is part of GNU Radio
5
*
6
* GNU Radio is free software; you can redistribute it and/or modify
7
* it under the terms of the GNU General Public License as published by
8
* the Free Software Foundation; either version 3, or (at your option)
9
* any later version.
10
*
11
* GNU Radio is distributed in the hope that it will be useful,
12
* but WITHOUT ANY WARRANTY; without even the implied warranty of
13
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14
* GNU General Public License for more details.
15
*
16
* You should have received a copy of the GNU General Public License
17
* along with GNU Radio; see the file COPYING. If not, write to
18
* the Free Software Foundation, Inc., 51 Franklin Street,
19
* Boston, MA 02110-1301, USA.
20
*/
21
22
#ifndef INCLUDED_DIGITAL_OFDM_SYNC_SC_CFB_H
23
#define INCLUDED_DIGITAL_OFDM_SYNC_SC_CFB_H
24
25
#include <
digital_api.h
>
26
#include <
gr_hier_block2.h
>
27
28
class
digital_ofdm_sync_sc_cfb
;
29
typedef
boost::shared_ptr<digital_ofdm_sync_sc_cfb>
digital_ofdm_sync_sc_cfb_sptr
;
30
31
/*! \param fft_len FFT length
32
* \param cp_len Length of the guard interval (cyclic prefix) in samples
33
* \param use_even_carriers If true, the carriers in the sync preamble are occupied such
34
* that the even carriers are used (0, 2, 4, ...). If you use all
35
* carriers, that would include the DC carrier, so be careful.
36
*/
37
DIGITAL_API
digital_ofdm_sync_sc_cfb_sptr
38
digital_make_ofdm_sync_sc_cfb
(
int
fft_len,
int
cp_len,
bool
use_even_carriers=
false
);
39
40
/*!
41
* \brief Schmidl & Cox synchronisation for OFDM
42
* \ingroup ofdm_blk
43
* \ingroup synchronizers_blk
44
*
45
* \details
46
* Input: complex samples.
47
* Output 0: Fine frequency offset, scaled by the OFDM symbol duration.
48
* This is \f$\hat{\varphi}\f$ in [1]. The normalized frequency
49
* offset is then 2.0*output0/fft_len.
50
* Output 1: Beginning of the first OFDM symbol after the first (doubled) OFDM
51
* symbol. The beginning is marked with a 1 (it's 0 everywhere else).
52
*
53
* The evaluation of the coarse frequency offset is *not* done in this block.
54
* Also, the initial equalizer taps are not calculated here.
55
*
56
* Note that we use a different normalization factor in the timing metric than
57
* the authors do in their original work[1]. If the timing metric (8) is
58
* \f[
59
* M(d) = \frac{|P(d)|^2}{(R(d))^2},
60
* \f]
61
* we calculate the normalization as
62
* \f[
63
* R(d) = \frac{1}{2} \sum_{k=0}^{N-1} |r_{k+d}|^2,
64
* \f]
65
* i.e., we estimate the energy from *both* half-symbols. This avoids spurious detects
66
* at the end of a burst, when the energy level suddenly drops.
67
*
68
* [1] Schmidl, T.M. and Cox, D.C., "Robust frequency and timing synchronization for OFDM",
69
* Communications, IEEE Transactions on, 1997.
70
*/
71
class
DIGITAL_API
digital_ofdm_sync_sc_cfb
:
public
gr_hier_block2
72
{
73
private
:
74
friend
DIGITAL_API
digital_ofdm_sync_sc_cfb_sptr
digital_make_ofdm_sync_sc_cfb
(
int
fft_len,
int
cp_len,
bool
use_even_carriers);
75
digital_ofdm_sync_sc_cfb
(
int
fft_len,
int
cp_len,
bool
use_even_carriers);
76
77
public
:
78
~
digital_ofdm_sync_sc_cfb
();
79
80
};
81
82
#endif
/* INCLUDED_DIGITAL_OFDM_SYNC_SC_CFB_H */
83
gr-digital
include
digital_ofdm_sync_sc_cfb.h
Generated on Mon Aug 19 2013 15:37:30 for GNU Radio 3.6.5.1 C++ API by
1.8.1.2