GNU Radio Manual and C++ API Reference 3.8.5.0
The Free & Open Software Radio Ecosystem
 
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fft_vfc.h
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1/* -*- c++ -*- */
2/*
3 * Copyright 2004,2010,2012,2018 Free Software Foundation, Inc.
4 *
5 * This file is part of GNU Radio
6 *
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 3, or (at your option)
10 * any later version.
11 *
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.
16 *
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.
21 */
22
23#ifndef INCLUDED_FFT_FFT_VFC_H
24#define INCLUDED_FFT_FFT_VFC_H
25
26#include <gnuradio/fft/api.h>
27#include <gnuradio/sync_block.h>
28
29namespace gr {
30namespace fft {
31
32/*!
33 * \brief Compute forward or reverse FFT. complex vector in / complex vector out.
34 * \ingroup fourier_analysis_blk
35 *
36 * The FFT operation is defined for a vector \f$x\f$ with \f$N\f$ uniformly
37 * sampled points by
38 *
39 * \f[ X(a) = \sum_{k=0}^{N-1} x(a) \cdot e^{-j 2\pi k a / N} \f]
40 *
41 * \f$ X = FFT\{x\} \f$ is the the FFT transform of \f$x(a)\f$, \f$j\f$ is
42 * the imaginary unit, \f$k\f$ and \f$a\f$ range from \f$0\f$ to \f$N-1\f$.
43 *
44 * The IFFT operation is defined for a vector \f$y\f$ with \f$N\f$
45 * uniformly sampled points by
46 *
47 * \f[ Y(b) = \sum_{k=0}^{N-1} y(b) \cdot e^{j 2\pi k b / N} \f]
48 *
49 * \f$Y = IFFT\{y\}\f$ is the the inverse FFT transform of \f$y(b)\f$,
50 * \f$j\f$ is the imaginary unit, \f$k\f$ and \f$b\f$ range from \f$0\f$ to
51 * \f$N-1\f$.
52 *
53 * \b Note, that due to the underlying FFTW library, the output of a FFT
54 * followed by an IFFT (or the other way around) will be scaled i.e.
55 * \f$FFT\{ \, IFFT\{x\} \,\} = N \cdot x \neq x\f$.
56 *
57 * \see http://www.fftw.org/faq/section3.html#whyscaled
58 */
59class FFT_API fft_vfc : virtual public sync_block
60{
61public:
62 // gr::fft::fft_vfc::sptr
63 typedef boost::shared_ptr<fft_vfc> sptr;
64
65 /*! \brief
66 * \param[in] fft_size N.
67 * \param[in] forward True performs FFT, False performs IFFT.
68 * \param[in] window Window function to be used.
69 * \param[in] nthreads Number of underlying threads.
70 */
71 static sptr
72 make(int fft_size, bool forward, const std::vector<float>& window, int nthreads = 1);
73
74 virtual void set_nthreads(int n) = 0;
75
76 virtual int nthreads() const = 0;
77
78 virtual bool set_window(const std::vector<float>& window) = 0;
79};
80
81} /* namespace fft */
82} /* namespace gr */
83
84#endif /* INCLUDED_FFT_FFT_VFC_H */
Compute forward or reverse FFT. complex vector in / complex vector out.
Definition fft_vfc.h:60
virtual bool set_window(const std::vector< float > &window)=0
virtual void set_nthreads(int n)=0
boost::shared_ptr< fft_vfc > sptr
Definition fft_vfc.h:63
virtual int nthreads() const =0
static sptr make(int fft_size, bool forward, const std::vector< float > &window, int nthreads=1)
Definition window.h:35
synchronous 1:1 input to output with history
Definition sync_block.h:38
#define FFT_API
Definition gr-fft/include/gnuradio/fft/api.h:30
GNU Radio logging wrapper for log4cpp library (C++ port of log4j)
Definition basic_block.h:46