digital: converted mpsk snr and probes to new style.

author: Tom Rondeau <trondeau@vt.edu> 2012-08-14 00:00:14 -0400
committer: Tom Rondeau <trondeau@vt.edu> 2012-08-14 00:00:14 -0400
commit: 48a95b3469febf4929c74f41beac6b33ab77566e (patch)
tree: 09fcfa18252f4e629f1bdb280b7ef0a12e1f401b /gr-digital/include/digital
parent: 509fddb30a70862b31b0488acfbbdf523b48af0d (diff)
5 files changed, 544 insertions, 4 deletions
diff --git a/gr-digital/include/digital/CMakeLists.txt b/gr-digital/include/digital/CMakeLists.txt
index 7d8545b185..2445a6fe37 100644
--- a/gr-digital/include/digital/CMakeLists.txt
+++ b/gr-digital/include/digital/CMakeLists.txt
@@ -77,7 +77,7 @@ install(FILES
     ${digital_generated_includes}
     api.h
     glfsr.h
-#    impl_mpsk_snr_est.h
+    mpsk_snr_est.h
     additive_scrambler_bb.h
     binary_slicer_fb.h
     clock_recovery_mm_cc.h
@@ -105,7 +105,7 @@ install(FILES
     map_bb.h
 #    metric_type.h
 #    mpsk_receiver_cc.h
-#    mpsk_snr_est_cc.h
+    mpsk_snr_est_cc.h
 #    ofdm_cyclic_prefixer.h
 #    ofdm_frame_acquisition.h
 #    ofdm_frame_sink.h
@@ -116,8 +116,8 @@ install(FILES
     pfb_clock_sync_ccf.h
     pfb_clock_sync_fff.h
     pn_correlator_cc.h
-#    probe_density_b.h
-#    probe_mpsk_snr_est_c.h
+    probe_density_b.h
+    probe_mpsk_snr_est_c.h
     scrambler_bb.h
 #    simple_framer.h
 #    simple_framer_sync.h
diff --git a/gr-digital/include/digital/mpsk_snr_est.h b/gr-digital/include/digital/mpsk_snr_est.h
new file mode 100644
index 0000000000..80dad77ce3
--- /dev/null
+++ b/gr-digital/include/digital/mpsk_snr_est.h
@@ -0,0 +1,287 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2011,2012 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.
+ */
+
+#ifndef INCLUDED_DIGITAL_MPSK_SNR_EST_H
+#define INCLUDED_DIGITAL_MPSK_SNR_EST_H
+
+#include <digital/api.h>
+#include <gr_complex.h>
+
+namespace gr {
+  namespace digital {
+
+    //! Enum for the type of SNR estimator to select
+    /*! \ingroup snr_blk
+     *  \anchor ref_snr_est_types
+     *
+     * Below are some ROUGH estimates of what values of SNR each of
+     * these types of estimators is good for. In general, these offer
+     * a trade-off between accuracy and performance.
+     *
+     * \li SNR_EST_SIMPLE:  Simple estimator (>= 7 dB)
+     * \li SNR_EST_SKEW:    Skewness-base est (>= 5 dB)
+     * \li SNR_EST_M2M4:    2nd & 4th moment est (>= 1 dB)
+     * \li SNR_EST_SVR:     SVR-based est (>= 0dB)
+     */
+    enum snr_est_type_t {
+      SNR_EST_SIMPLE = 0,   // Simple estimator (>= 7 dB)
+      SNR_EST_SKEW,	    // Skewness-base est (>= 5 dB)
+      SNR_EST_M2M4,         // 2nd & 4th moment est (>= 1 dB)
+      SNR_EST_SVR           // SVR-based est (>= 0dB)
+    };
+
+    /*! \brief A parent class for SNR estimators, specifically for
+     *  M-PSK signals in AWGN channels.
+     *  \ingroup snr_blk
+     */
+    class DIGITAL_API mpsk_snr_est
+    {
+    protected:
+      double d_alpha, d_beta;
+
+    public:
+      /*! Constructor
+       *
+       *  Parameters:
+       *  \param alpha: the update rate of internal running average
+       *  calculations.
+       */
+      mpsk_snr_est(double alpha);
+      virtual ~mpsk_snr_est();
+
+      //! Get the running-average coefficient
+      double alpha() const;
+
+      //! Set the running-average coefficient
+      void set_alpha(double alpha);
+
+      //! Update the current registers
+      virtual int update(int noutput_items,
+			 const gr_complex *input);
+
+      //! Use the register values to compute a new estimate
+      virtual double snr();
+    };
+
+
+    //! \brief SNR Estimator using simple mean/variance estimates.
+    /*! \ingroup snr_blk
+     *
+     *  A very simple SNR estimator that just uses mean and variance
+     *  estimates of an M-PSK constellation. This esimator is quick
+     *  and cheap and accurate for high SNR (above 7 dB or so) but
+     *  quickly starts to overestimate the SNR at low SNR.
+     */
+    class DIGITAL_API mpsk_snr_est_simple :
+      public mpsk_snr_est
+    {
+    private:
+      double d_y1, d_y2;
+  
+    public:
+      /*! Constructor
+       *
+       *  Parameters:
+       *  \param alpha: the update rate of internal running average
+       *  calculations.
+       */
+      mpsk_snr_est_simple(double alpha);
+      ~mpsk_snr_est_simple() {}
+
+      int update(int noutput_items,
+		 const gr_complex *input);
+      double snr();
+    };
+
+
+    //! \brief SNR Estimator using skewness correction.
+    /*!  \ingroup snr_blk
+     *
+     *  This is an estimator that came from a discussion between Tom
+     *  Rondeau and fred harris with no known paper reference. The
+     *  idea is that at low SNR, the variance estimations will be
+     *  affected because of fold-over around the decision boundaries,
+     *  which results in a skewness to the samples. We estimate the
+     *  skewness and use this as a correcting term.
+     */
+    class DIGITAL_API mpsk_snr_est_skew :
+      public mpsk_snr_est
+    {
+    private:
+      double d_y1, d_y2, d_y3;
+  
+    public:
+      /*! Constructor
+       *
+       *  Parameters:
+       *  \param alpha: the update rate of internal running average
+       *  calculations.
+       */
+      mpsk_snr_est_skew(double alpha);
+      ~mpsk_snr_est_skew() {}
+
+      int update(int noutput_items,
+		 const gr_complex *input);
+      double snr();
+    };
+
+
+    //! \brief SNR Estimator using 2nd and 4th-order moments.
+    /*! \ingroup snr_blk
+     *
+     *  An SNR estimator for M-PSK signals that uses 2nd (M2) and 4th
+     *  (M4) order moments. This estimator uses knowledge of the
+     *  kurtosis of the signal (k_a) and noise (k_w) to make its
+     *  estimation. We use Beaulieu's approximations here to M-PSK
+     *  signals and AWGN channels such that k_a=1 and k_w=2. These
+     *  approximations significantly reduce the complexity of the
+     *  calculations (and computations) required.
+     *
+     *  Reference:
+     *  D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR
+     *  estimation techniques for the AWGN channel," IEEE
+     *  Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000.
+     */
+    class DIGITAL_API mpsk_snr_est_m2m4 :
+      public mpsk_snr_est
+    {
+    private:
+      double d_y1, d_y2;
+  
+    public:
+      /*! Constructor
+       *
+       *  Parameters:
+       *  \param alpha: the update rate of internal running average
+       *  calculations.
+       */
+      mpsk_snr_est_m2m4(double alpha);
+      ~mpsk_snr_est_m2m4() {}
+
+      int update(int noutput_items,
+		 const gr_complex *input);
+      double snr();
+    };
+
+
+    //! \brief SNR Estimator using 2nd and 4th-order moments.
+    /*!  \ingroup snr_blk
+     *
+     *  An SNR estimator for M-PSK signals that uses 2nd (M2) and 4th
+     *  (M4) order moments. This estimator uses knowledge of the
+     *  kurtosis of the signal (k_a) and noise (k_w) to make its
+     *  estimation. In this case, you can set your own estimations for
+     *  k_a and k_w, the kurtosis of the signal and noise, to fit this
+     *  estimation better to your signal and channel conditions.
+     *
+     *  A word of warning: this estimator has not been fully tested or
+     *  proved with any amount of rigor. The estimation for M4 in
+     *  particular might be ignoring effectf of when k_a and k_w are
+     *  different. Use this estimator with caution and a copy of the
+     *  reference on hand.
+     *
+     *  The digital_mpsk_snr_est_m2m4 assumes k_a and k_w to simplify
+     *  the computations for M-PSK and AWGN channels. Use that
+     *  estimator unless you have a way to guess or estimate these
+     *  values here.
+     *
+     *  Original paper: 
+     *  R. Matzner, "An SNR estimation algorithm for complex baseband
+     *  signal using higher order statistics," Facta Universitatis
+     *  (Nis), no. 6, pp. 41-52, 1993.
+     *
+     *  Reference used in derivation:
+     *  D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR
+     *  estimation techniques for the AWGN channel," IEEE
+     *  Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000.
+     */
+    class DIGITAL_API snr_est_m2m4 :
+      public mpsk_snr_est
+    {
+    private:
+      double d_y1, d_y2;
+      double d_ka, d_kw;
+  
+    public:
+      /*! Constructor
+       *
+       *  Parameters:
+       *  \param alpha: the update rate of internal running average
+       *  calculations.
+       *  \param ka: estimate of the signal kurtosis (1 for PSK)
+       *  \param kw: estimate of the channel noise kurtosis (2 for AWGN)
+       */
+      snr_est_m2m4(double alpha, double ka, double kw);
+      ~snr_est_m2m4() {}
+
+      int update(int noutput_items,
+		 const gr_complex *input);
+      double snr();
+    };
+
+
+    //! \brief Signal-to-Variation Ratio SNR Estimator.
+    /*! \ingroup snr_blk
+     *
+     *  This estimator actually comes from an SNR estimator for M-PSK
+     *  signals in fading channels, but this implementation is
+     *  specifically for AWGN channels. The math was simplified to
+     *  assume a signal and noise kurtosis (k_a and k_w) for M-PSK
+     *  signals in AWGN. These approximations significantly reduce the
+     *  complexity of the calculations (and computations) required.
+     *
+     *  Original paper:
+     *  A. L. Brandao, L. B. Lopes, and D. C. McLernon, "In-service
+     *  monitoring of multipath delay and cochannel interference for
+     *  indoor mobile communication systems," Proc. IEEE
+     *  Int. Conf. Communications, vol. 3, pp. 1458-1462, May 1994.
+     *
+     *  Reference:
+     *  D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR
+     *  estimation techniques for the AWGN channel," IEEE
+     *  Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000.
+     */
+    class DIGITAL_API mpsk_snr_est_svr :
+      public mpsk_snr_est
+    {
+    private:
+      double d_y1, d_y2;
+  
+    public:
+      /*! Constructor
+       *
+       *  Parameters:
+       *  \param alpha: the update rate of internal running average
+       *  calculations.
+       */
+      mpsk_snr_est_svr(double alpha);
+      ~mpsk_snr_est_svr() {}
+
+      int update(int noutput_items,
+		 const gr_complex *input);
+      double snr();
+    };
+
+  } /* namespace digital */
+} /* namespace gr */
+
+#endif /* INCLUDED_DIGITAL_MPSK_SNR_EST_H */
diff --git a/gr-digital/include/digital/mpsk_snr_est_cc.h b/gr-digital/include/digital/mpsk_snr_est_cc.h
new file mode 100644
index 0000000000..e6cc511dc7
--- /dev/null
+++ b/gr-digital/include/digital/mpsk_snr_est_cc.h
@@ -0,0 +1,96 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2011,2012 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.
+ */
+
+#ifndef INCLUDED_DIGITAL_MPSK_SNR_EST_CC_H
+#define INCLUDED_DIGITAL_MPSK_SNR_EST_CC_H
+
+#include <digital/api.h>
+#include <digital/mpsk_snr_est.h>
+#include <gr_sync_block.h>
+
+namespace gr {
+  namespace digital {
+
+    //! \brief A block for computing SNR of a signal.
+    /*! \ingroup snr_blk
+     *
+     *  This block can be used to monitor and retrieve estimations of
+     *  the signal SNR. It is designed to work in a flowgraph and
+     *  passes all incoming data along to its output.
+     *
+     *  The block is designed for use with M-PSK signals
+     *  especially. The type of estimator is specified as the \p type
+     *  parameter in the constructor. The estimators tend to trade off
+     *  performance for accuracy, although experimentation should be
+     *  done to figure out the right approach for a given
+     *  implementation. Further, the current set of estimators are
+     *  designed and proven theoretically under AWGN conditions; some
+     *  amount of error should be assumed and/or estimated for real
+     *  channel conditions.
+     */
+    class DIGITAL_API mpsk_snr_est_cc : virtual public gr_sync_block
+    {
+    public:
+      // gr::digital::mpsk_snr_est_cc::sptr
+      typedef boost::shared_ptr<mpsk_snr_est_cc> sptr;
+
+      /*! Factory function returning shared pointer of this class
+       *
+       *  Parameters:
+       *
+       *  \param type: the type of estimator to use \ref ref_snr_est_types
+       *  "snr_est_type_t" for details about the available types.
+       *  \param tag_nsamples: after this many samples, a tag containing
+       *  the SNR (key='snr') will be sent
+       *  \param alpha: the update rate of internal running average
+       *  calculations.
+       */
+      static sptr make(snr_est_type_t type,
+		       int tag_nsamples,
+		       double alpha);
+
+      //! Return the estimated signal-to-noise ratio in decibels
+      virtual double snr() = 0;
+
+      //! Return the type of estimator in use
+      virtual snr_est_type_t type() const = 0;
+
+      //! Return how many samples between SNR tags
+      virtual int tag_nsample() const = 0;
+
+      //! Get the running-average coefficient
+      virtual double alpha() const = 0;
+
+      //! Set type of estimator to use
+      virtual void set_type(snr_est_type_t t) = 0;
+
+      //! Set the number of samples between SNR tags
+      virtual void set_tag_nsample(int n) = 0;
+
+      //! Set the running-average coefficient
+      virtual void set_alpha(double alpha) = 0;
+    };
+
+  } /* namespace digital */
+} /* namespace gr */
+
+#endif /* INCLUDED_DIGITAL_MPSK_SNR_EST_CC_H */
diff --git a/gr-digital/include/digital/probe_density_b.h b/gr-digital/include/digital/probe_density_b.h
new file mode 100644
index 0000000000..7459663fe1
--- /dev/null
+++ b/gr-digital/include/digital/probe_density_b.h
@@ -0,0 +1,63 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2008,2012 Free Software Foundation, Inc.
+ *
+ * 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.
+ */
+
+#ifndef INCLUDED_GR_PROBE_DENSITY_B_H
+#define INCLUDED_GR_PROBE_DENSITY_B_H
+
+#include <digital/api.h>
+#include <gr_sync_block.h>
+
+namespace gr {
+  namespace digital {
+
+    /*!
+     * This block maintains a running average of the input stream and
+     * makes it available as an accessor function.  The input stream
+     * is type unsigned char.
+     *
+     * If you send this block a stream of unpacked bytes, it will tell
+     * you what the bit density is.
+     *
+     * \param alpha  Average filter constant
+     *
+     */
+    class DIGITAL_API probe_density_b : virtual public gr_sync_block
+    {
+    public:
+      // gr::digital::probe_density_b::sptr
+      typedef boost::shared_ptr<probe_density_b> sptr;
+
+      static sptr make(double alpha);
+
+      /*!
+       * \brief Returns the current density value
+       */
+      virtual double density() const = 0;
+
+      /*!
+       * \brief Set the average filter constant
+       */
+      virtual void set_alpha(double alpha) = 0;
+    };
+
+  } /* namespace digital */
+} /* namespace gr */
+
+#endif /* INCLUDED_GR_PROBE_DENSITY_B_H */
diff --git a/gr-digital/include/digital/probe_mpsk_snr_est_c.h b/gr-digital/include/digital/probe_mpsk_snr_est_c.h
new file mode 100644
index 0000000000..d65e8e1b6e
--- /dev/null
+++ b/gr-digital/include/digital/probe_mpsk_snr_est_c.h
@@ -0,0 +1,94 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2011,2012 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.
+ */
+
+#ifndef INCLUDED_DIGITAL_PROBE_MPSK_SNR_EST_C_H
+#define INCLUDED_DIGITAL_PROBE_MPSK_SNR_EST_C_H
+
+#include <digital/api.h>
+#include <digital/mpsk_snr_est.h>
+#include <gr_sync_block.h>
+
+namespace gr {
+  namespace digital {
+
+    //! \brief A probe for computing SNR of a signal.
+    /*! \ingroup snr_blk
+     *
+     *  This is a probe block (a sink) that can be used to monitor and
+     *  retrieve estimations of the signal SNR. This probe is designed
+     *  for use with M-PSK signals especially. The type of estimator
+     *  is specified as the \p type parameter in the constructor. The
+     *  estimators tend to trade off performance for accuracy,
+     *  although experimentation should be done to figure out the
+     *  right approach for a given implementation. Further, the
+     *  current set of estimators are designed and proven
+     *  theoretically under AWGN conditions; some amount of error
+     *  should be assumed and/or estimated for real channel
+     *  conditions.
+     */
+    class DIGITAL_API probe_mpsk_snr_est_c : virtual public gr_sync_block
+    {
+    public:
+      // gr::digital::probe_mpsk_snr_est_c::sptr
+      typedef boost::shared_ptr<probe_mpsk_snr_est_c> sptr;
+
+      /*! Make an MPSK SNR probe.
+       *
+       *  Parameters:
+       *
+       *  \param type: the type of estimator to use \ref ref_snr_est_types
+       *  "snr_est_type_t" for details about the available types.
+       *  \param msg_nsamples: [not implemented yet] after this many
+       *  samples, a message containing the SNR (key='snr') will be sent
+       *  \param alpha: the update rate of internal running average
+       *  calculations.
+       */
+      static sptr make(snr_est_type_t type,
+		       int msg_nsamples,
+		       double alpha);
+
+      //! Return the estimated signal-to-noise ratio in decibels
+      virtual double snr() = 0;
+
+      //! Return the type of estimator in use
+      virtual snr_est_type_t type() const = 0;
+
+      //! Return how many samples between SNR messages
+      virtual int msg_nsample() const = 0;
+
+      //! Get the running-average coefficient
+      virtual double alpha() const = 0;
+
+      //! Set type of estimator to use
+      virtual void set_type(snr_est_type_t t) = 0;
+
+      //! Set the number of samples between SNR messages
+      virtual void set_msg_nsample(int n) = 0;
+
+      //! Set the running-average coefficient
+      virtual void set_alpha(double alpha) = 0;
+    };
+
+  } /* namespace digital */
+} /* namespace gr */
+
+#endif /* INCLUDED_DIGITAL_PROBE_MPSK_SNR_EST_C_H */
author	Tom Rondeau <trondeau@vt.edu>	2012-08-14 00:00:14 -0400
committer	Tom Rondeau <trondeau@vt.edu>	2012-08-14 00:00:14 -0400
commit	48a95b3469febf4929c74f41beac6b33ab77566e (patch)
tree	09fcfa18252f4e629f1bdb280b7ef0a12e1f401b /gr-digital/include/digital
parent	509fddb30a70862b31b0488acfbbdf523b48af0d (diff)