GNU Radio 3.5.3.2 C++ API
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00001 /* -*- c++ -*- */ 00002 /* 00003 * Copyright 2002 Free Software Foundation, Inc. 00004 * 00005 * This file is part of GNU Radio 00006 * 00007 * GNU Radio is free software; you can redistribute it and/or modify 00008 * it under the terms of the GNU General Public License as published by 00009 * the Free Software Foundation; either version 3, or (at your option) 00010 * any later version. 00011 * 00012 * GNU Radio is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 * GNU General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU General Public License 00018 * along with GNU Radio; see the file COPYING. If not, write to 00019 * the Free Software Foundation, Inc., 51 Franklin Street, 00020 * Boston, MA 02110-1301, USA. 00021 */ 00022 #ifndef _GRI_MMSE_FIR_INTERPOLATOR_H_ 00023 #define _GRI_MMSE_FIR_INTERPOLATOR_H_ 00024 00025 #include <gr_core_api.h> 00026 #include <vector> 00027 00028 class gr_fir_fff; 00029 00030 /*! 00031 * \brief Compute intermediate samples between signal samples x(k*Ts) 00032 * \ingroup filter_primitive 00033 * 00034 * This implements a Mininum Mean Squared Error interpolator with 8 taps. 00035 * It is suitable for signals where the bandwidth of interest B = 1/(4*Ts) 00036 * Where Ts is the time between samples. 00037 * 00038 * Although mu, the fractional delay, is specified as a float, it is actually 00039 * quantized. 0.0 <= mu <= 1.0. That is, mu is quantized in the interpolate 00040 * method to 32nd's of a sample. 00041 * 00042 * For more information, in the GNU Radio source code, see: 00043 * \li gnuradio-core/src/gen_interpolator_taps/README 00044 * \li gnuradio-core/src/gen_interpolator_taps/praxis.txt 00045 */ 00046 00047 class GR_CORE_API gri_mmse_fir_interpolator { 00048 public: 00049 gri_mmse_fir_interpolator (); 00050 ~gri_mmse_fir_interpolator (); 00051 00052 unsigned ntaps () const; 00053 unsigned nsteps () const; 00054 00055 /*! 00056 * \brief compute a single interpolated output value. 00057 * \p input must have ntaps() valid entries. 00058 * input[0] .. input[ntaps() - 1] are referenced to compute the output value. 00059 * 00060 * \p mu must be in the range [0, 1] and specifies the fractional delay. 00061 * 00062 * \returns the interpolated input value. 00063 */ 00064 float interpolate (const float input[], float mu) const; 00065 00066 protected: 00067 std::vector<gr_fir_fff *> filters; 00068 }; 00069 00070 00071 #endif /* _GRI_MMSE_FIR_INTERPOLATOR_H_ */