From 85e2ae3d74d8288ff332f960c5108dc6c2096073 Mon Sep 17 00:00:00 2001
From: Hannes Matuschek <hmatuschek@gmail.com>
Date: Thu, 18 Dec 2014 14:49:33 +0100
Subject: [PATCH] Added Schumann resonances example.

---
 examples/CMakeLists.txt  |   4 ++
 examples/schumann.cc     |   2 +
 examples/schumann.hh     | 106 +++++++++++++++++++++++++++++++++++++++
 examples/sdr_schumann.cc |  40 +++++++++++++++
 4 files changed, 152 insertions(+)
 create mode 100644 examples/schumann.cc
 create mode 100644 examples/schumann.hh
 create mode 100644 examples/sdr_schumann.cc

diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 7e405f8..a0aab40 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -15,6 +15,10 @@ IF(SDR_WITH_PORTAUDIO)
 
  add_executable(sdr_afsk1200 sdr_afsk1200.cc)
  target_link_libraries(sdr_afsk1200 ${LIBS} libsdr)
+
+ qt5_wrap_cpp(sdr_schumann_MOC_SOURCES schumann.hh)
+ add_executable(sdr_schumann sdr_schumann.cc schumann.cc ${sdr_schumann_MOC_SOURCES})
+ target_link_libraries(sdr_schumann ${LIBS} libsdr libsdr-gui)
 ENDIF(SDR_WITH_PORTAUDIO)
 
 IF(SDR_WITH_QT5 AND SDR_WITH_FFTW AND SDR_WITH_PORTAUDIO)
diff --git a/examples/schumann.cc b/examples/schumann.cc
new file mode 100644
index 0000000..75ffcbb
--- /dev/null
+++ b/examples/schumann.cc
@@ -0,0 +1,2 @@
+#include "schumann.hh"
+
diff --git a/examples/schumann.hh b/examples/schumann.hh
new file mode 100644
index 0000000..8738233
--- /dev/null
+++ b/examples/schumann.hh
@@ -0,0 +1,106 @@
+#ifndef SCHUMANN_HH
+#define SCHUMANN_HH
+
+#include <libsdr/sdr.hh>
+#include <libsdr/gui/gui.hh>
+
+class Schumann: public sdr::gui::SpectrumProvider, public sdr::Sink<int16_t>
+{
+  Q_OBJECT
+
+public:
+  explicit Schumann(QObject *parent=0)
+    : sdr::gui::SpectrumProvider(parent), sdr::Sink<int16_t>(),
+      _buffer_idx(0), _avg_count(0), _buffer(2048), _spectrum(2048),
+      _spec_count(0), _avg_spectrum(2048), _subsample(0), _Fs(0), _fft(_buffer, sdr::FFT::FORWARD)
+  {
+    // init spectrum and buffer
+    for (size_t i=0; i<2048; i++) {
+      _buffer[i] = 0;
+      _spectrum[i] = 0;
+    }
+  }
+
+  virtual ~Schumann() {
+    // pass...
+  }
+
+  void config(const sdr::Config &src_cfg) {
+    // Requires type, sample rate & buffer size
+    if (!src_cfg.hasType() || !src_cfg.hasSampleRate() || !src_cfg.hasBufferSize()) { return; }
+
+    // Check buffer type
+    if (sdr::Config::typeId< int16_t >() != src_cfg.type()) {
+      sdr::ConfigError err;
+      err << "Can not configure Schumann: Invalid type " << src_cfg.type()
+          << ", expected " << sdr::Config::typeId<int16_t>();
+      throw err;
+    }
+
+    // Check input sample rate
+    double Fs = src_cfg.sampleRate();
+    if (40 > Fs) {
+      sdr::ConfigError err;
+      err << "Can not configure Schumann: Input sample rate too low! The Schumann node requires at "
+          << "least a sample rate of 40Hz, got " << Fs << "Hz";
+      throw err;
+    }
+
+    // Compute subsample
+    _subsample = Fs/40; _Fs = Fs/_subsample;
+  }
+
+  void process(const sdr::Buffer<int16_t> &buffer, bool allow_overwrite) {
+    for (size_t i=0; i<buffer.size(); i++) {
+      // Add value to buffer
+      _buffer[_buffer_idx] += float(buffer[i])/((1<<15)*_subsample); _avg_count++;
+      // If subsample count is reached:
+      if (_avg_count == _subsample) { _buffer_idx++; _avg_count = 0; }
+      if (_buffer_idx < 2048) { _buffer[_buffer_idx] = 0; }
+      if (_buffer_idx == 2048) {
+        // Compute FFT and add to spectrum:
+        _fft();
+        _spec_count++;
+        for (size_t i=0; i<2048; i++) {
+          _spectrum[i] += _buffer[i].real()*_buffer[i].real() + _buffer[i].imag()*_buffer[i].imag();
+          _avg_spectrum[i] = 10*(_spectrum[i]/_spec_count);
+          std::cout << _avg_spectrum[i] << "\t";
+        }
+        std::cout << std::endl;
+        _buffer[0] = 0; _buffer_idx=0;
+        emit spectrumUpdated();
+      }
+    }
+  }
+
+  bool isInputReal() const {
+    return true;
+  }
+
+  double sampleRate() const {
+    return _Fs;
+  }
+
+  size_t fftSize() const {
+    return 2048;
+  }
+
+  const sdr::Buffer<double> &spectrum() const {
+    return _avg_spectrum;
+  }
+
+protected:
+  size_t _buffer_idx;
+  size_t _avg_count;
+  sdr::Buffer< std::complex<float> > _buffer;
+  sdr::Buffer< double > _spectrum;
+  size_t _spec_count;
+  sdr::Buffer< double > _avg_spectrum;
+  size_t _subsample;
+  double _Fs;
+  sdr::FFTPlan<float> _fft;
+};
+
+
+
+#endif // SCHUMANN_HH
diff --git a/examples/sdr_schumann.cc b/examples/sdr_schumann.cc
new file mode 100644
index 0000000..3de44cc
--- /dev/null
+++ b/examples/sdr_schumann.cc
@@ -0,0 +1,40 @@
+#include <libsdr/sdr.hh>
+#include <signal.h>
+#include <libsdr/gui/gui.hh>
+
+#include <QApplication>
+#include <QMainWindow>
+#include "schumann.hh"
+
+
+using namespace sdr;
+
+
+
+int main(int argc, char *argv[])
+{
+  QApplication app(argc, argv);
+
+  sdr::PortAudio::init();
+
+  sdr::PortSource<int16_t> src(32000, 1024);
+  Schumann schumann;
+  src.connect(&schumann);
+
+  QMainWindow *win = new QMainWindow();
+  sdr::gui::SpectrumView *view = new sdr::gui::SpectrumView(&schumann);
+  win->setCentralWidget(view);
+  win->show();
+
+  sdr::Queue::get().addIdle(&src, &sdr::PortSource<int16_t>::next);
+
+  sdr::Queue::get().start();
+  app.exec();
+
+  sdr::Queue::get().stop();
+  sdr::Queue::get().wait();
+
+  sdr::PortAudio::terminate();
+
+  return 0;
+}