GNU Radio 3.5.1 C++ API
gr_pwr_squelch_cc.h
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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2006 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 
00023 #ifndef INCLUDED_GR_PWR_SQUELCH_CC_H
00024 #define INCLUDED_GR_PWR_SQUELCH_CC_H
00025 
00026 #include <gr_core_api.h>
00027 #include <cmath>
00028 #include <gr_squelch_base_cc.h>
00029 #include <gr_single_pole_iir.h>
00030 
00031 class gr_pwr_squelch_cc;
00032 typedef boost::shared_ptr<gr_pwr_squelch_cc> gr_pwr_squelch_cc_sptr;
00033 
00034 GR_CORE_API gr_pwr_squelch_cc_sptr 
00035 gr_make_pwr_squelch_cc(double db, double alpha = 0.0001, int ramp=0, bool gate=false);
00036 
00037 /*!
00038  * \brief gate or zero output when input power below threshold
00039  * \ingroup level_blk
00040  */
00041 class GR_CORE_API gr_pwr_squelch_cc : public gr_squelch_base_cc
00042 {
00043 private:
00044   double d_threshold;
00045   double d_pwr;
00046   gr_single_pole_iir<double,double,double> d_iir;
00047 
00048   friend GR_CORE_API gr_pwr_squelch_cc_sptr gr_make_pwr_squelch_cc(double db, double alpha, int ramp, bool gate);
00049   gr_pwr_squelch_cc(double db, double alpha, int ramp, bool gate);
00050 
00051 protected:
00052   virtual void update_state(const gr_complex &in);
00053   virtual bool mute() const { return d_pwr < d_threshold; }
00054   
00055 public:
00056   std::vector<float> squelch_range() const;
00057 
00058   double threshold() const { return 10*log10(d_threshold); }
00059   void set_threshold(double db) { d_threshold = std::pow(10.0, db/10); }
00060   void set_alpha(double alpha) { d_iir.set_taps(alpha); }
00061 };
00062 
00063 #endif /* INCLUDED_GR_PWR_SQUELCH_CC_H */