Started the AFSK decoder.

The clock recovery mechanism of GNU Radio is considered
an overkill for the needs of AFSK. So the afsk_decoder
will focus on a frequency domain approach.

grc/CMakeLists.txt

@@ -21,5 +21,6 @@ install(FILES
     satnogs_morse_decoder.xml
     satnogs_morse_debug_source.xml
     satnogs_clear_text_msg_sink.xml
-    satnogs_cw_to_symbol.xml DESTINATION share/gnuradio/grc/blocks
+    satnogs_cw_to_symbol.xml
+    satnogs_afsk_decoder.xml DESTINATION share/gnuradio/grc/blocks
 )

grc/satnogs_afsk_decoder.xml

@@ -0,0 +1,38 @@
+<?xml version="1.0"?>
+<block>
+  <name>afsk_decoder</name>
+  <key>satnogs_afsk_decoder</key>
+  <category>satnogs</category>
+  <import>import satnogs</import>
+  <make>satnogs.afsk_decoder($sampling_rate, $baudrate, $fft_size)</make>
+  <!-- Make one 'param' node for every Parameter you want settable from the GUI.
+       Sub-nodes:
+       * name
+       * key (makes the value accessible as $keyname, e.g. in the make node)
+       * type -->
+  <param>
+    <name>...</name>
+    <key>...</key>
+    <type>...</type>
+  </param>
+
+  <!-- Make one 'sink' node per input. Sub-nodes:
+       * name (an identifier for the GUI)
+       * type
+       * vlen
+       * optional (set to 1 for optional inputs) -->
+  <sink>
+    <name>in</name>
+    <type><!-- e.g. int, float, complex, byte, short, xxx_vector, ...--></type>
+  </sink>
+
+  <!-- Make one 'source' node per output. Sub-nodes:
+       * name (an identifier for the GUI)
+       * type
+       * vlen
+       * optional (set to 1 for optional inputs) -->
+  <source>
+    <name>out</name>
+    <type><!-- e.g. int, float, complex, byte, short, xxx_vector, ...--></type>
+  </source>
+</block>

include/satnogs/CMakeLists.txt

@@ -30,5 +30,6 @@ install(FILES
     morse_decoder.h
     morse_debug_source.h
     clear_text_msg_sink.h
-    cw_to_symbol.h DESTINATION include/satnogs
+    cw_to_symbol.h
+    afsk_decoder.h DESTINATION include/satnogs
 )

include/satnogs/afsk_decoder.h

@@ -0,0 +1,63 @@
+/* -*- c++ -*- */
+/*
+ * gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
+ *
+ *  Copyright (C) 2016, Libre Space Foundation <http://librespacefoundation.org/>
+ *
+ *  This program 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 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef INCLUDED_SATNOGS_AFSK_DECODER_H
+#define INCLUDED_SATNOGS_AFSK_DECODER_H
+
+#include <satnogs/api.h>
+#include <gnuradio/block.h>
+
+namespace gr {
+  namespace satnogs {
+
+    /*!
+     * \brief AFSK decoder. This particular decoder uses a Frequency Domain
+     * approach to retrieve the message.
+     * \ingroup satnogs
+     *
+     */
+    class SATNOGS_API afsk_decoder : virtual public gr::block
+    {
+     public:
+      typedef boost::shared_ptr<afsk_decoder> sptr;
+
+
+      /*!
+       * An AFSK decoder.
+       * @param sampling_rate the input sampling rate
+       * @param baudrate the baudrate (symbols per second)
+       * @param fft_size the FFT size that the decoder will use.
+       * @param auto_carrier_tracking if set to yes, the decoder will try
+       * to automatically find the mark and space frequencies
+       * @param mark_freq the frequency of the mark (1)
+       * @param mark_space the frequency of the space (0)
+       */
+      static sptr make(double sampling_rate, size_t baudrate = 1200,
+		       size_t fft_size = 128,
+		       bool auto_carrier_tracking = false,
+		       double mark_freq = 2400.0,
+		       double space_freq = 1200.0);
+    };
+
+  } // namespace satnogs
+} // namespace gr
+
+#endif /* INCLUDED_SATNOGS_AFSK_DECODER_H */
+

lib/CMakeLists.txt

@@ -30,7 +30,8 @@ list(APPEND satnogs_sources
     morse_decoder_impl.cc
     morse_debug_source_impl.cc
     clear_text_msg_sink_impl.cc
-    cw_to_symbol_impl.cc )
+    cw_to_symbol_impl.cc
+    afsk_decoder_impl.cc )
 
 set(satnogs_sources "${satnogs_sources}" PARENT_SCOPE)
 if(NOT satnogs_sources)

lib/afsk_decoder_impl.cc

@@ -0,0 +1,97 @@
+/* -*- c++ -*- */
+/*
+ * gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
+ *
+ *  Copyright (C) 2016, Libre Space Foundation <http://librespacefoundation.org/>
+ *
+ *  This program 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 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gnuradio/io_signature.h>
+#include "afsk_decoder_impl.h"
+
+namespace gr
+{
+  namespace satnogs
+  {
+
+    afsk_decoder::sptr
+    afsk_decoder::make (double sampling_rate, size_t samples_per_sym,
+		       size_t fft_size,
+		       bool auto_carrier_tracking,
+		       double mark_freq,
+		       double space_freq)
+    {
+      return gnuradio::get_initial_sptr (
+	  new afsk_decoder_impl (sampling_rate, samples_per_sym, fft_size,
+				 auto_carrier_tracking,
+				 mark_freq, space_freq));
+    }
+    /*
+     * The private constructor
+     */
+    afsk_decoder_impl::afsk_decoder_impl (double sampling_rate, size_t samples_per_sym,
+					  size_t fft_size,
+					  bool auto_carrier_tracking,
+					  double mark_freq, double space_freq) :
+	gr::block ("afsk_decoder",
+		   gr::io_signature::make (1, 1, fft_size * sizeof(float)),
+		   gr::io_signature::make (1, 1, sizeof(char))),
+		   d_samp_rate(sampling_rate),
+		   d_samples_per_sym(samples_per_sym),
+		   d_fft_size(fft_size),
+		   d_carriers_found(!auto_carrier_tracking),
+		   d_mark_freq(mark_freq),
+		   d_space_freq(space_freq)
+    {
+      if(auto_carrier_tracking){
+	d_mark_freq = d_space_freq = 0.0;
+      }
+    }
+
+    /*
+     * Our virtual destructor.
+     */
+    afsk_decoder_impl::~afsk_decoder_impl ()
+    {
+    }
+
+    void
+    afsk_decoder_impl::forecast (int noutput_items,
+				 gr_vector_int &ninput_items_required)
+    {
+      ninput_items_required[0] = noutput_items;
+    }
+
+    int
+    afsk_decoder_impl::general_work (int noutput_items,
+				     gr_vector_int &ninput_items,
+				     gr_vector_const_void_star &input_items,
+				     gr_vector_void_star &output_items)
+    {
+      const float *in = (const float *) input_items[0];
+
+      consume_each (noutput_items);
+
+      // Tell runtime system how many output items we produced.
+      return noutput_items;
+    }
+
+  } /* namespace satnogs */
+} /* namespace gr */
+

lib/afsk_decoder_impl.h

@@ -0,0 +1,62 @@
+/* -*- c++ -*- */
+/*
+ * gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
+ *
+ *  Copyright (C) 2016, Libre Space Foundation <http://librespacefoundation.org/>
+ *
+ *  This program 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 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef INCLUDED_SATNOGS_AFSK_DECODER_IMPL_H
+#define INCLUDED_SATNOGS_AFSK_DECODER_IMPL_H
+
+#include <satnogs/afsk_decoder.h>
+
+namespace gr
+{
+  namespace satnogs
+  {
+
+    class afsk_decoder_impl : public afsk_decoder
+    {
+    private:
+      const double d_samp_rate;
+      const size_t d_samples_per_sym;
+      const size_t d_fft_size;
+      bool d_carriers_found;
+      double d_mark_freq;
+      double d_space_freq;
+
+
+    public:
+      afsk_decoder_impl (double sampling_rate, size_t baudrate, size_t fft_size,
+			 bool auto_carrier_tracking, double mark_freq,
+			 double space_freq);
+      ~afsk_decoder_impl ();
+
+      // Where all the action really happens
+      void
+      forecast (int noutput_items, gr_vector_int &ninput_items_required);
+
+      int
+      general_work (int noutput_items, gr_vector_int &ninput_items,
+		    gr_vector_const_void_star &input_items,
+		    gr_vector_void_star &output_items);
+    };
+
+  } // namespace satnogs
+} // namespace gr
+
+#endif /* INCLUDED_SATNOGS_AFSK_DECODER_IMPL_H */
+

swig/satnogs_swig.i

@@ -14,6 +14,7 @@
 #include "satnogs/morse_debug_source.h"
 #include "satnogs/clear_text_msg_sink.h"
 #include "satnogs/cw_to_symbol.h"
+#include "satnogs/afsk_decoder.h"
 %}
 
 %include "satnogs/cw_matched_filter_ff.h"
@@ -27,3 +28,5 @@ GR_SWIG_BLOCK_MAGIC2(satnogs, morse_debug_source);
 GR_SWIG_BLOCK_MAGIC2(satnogs, clear_text_msg_sink);
 %include "satnogs/cw_to_symbol.h"
 GR_SWIG_BLOCK_MAGIC2(satnogs, cw_to_symbol);
+%include "satnogs/afsk_decoder.h"
+GR_SWIG_BLOCK_MAGIC2(satnogs, afsk_decoder);