Spectrum frequency zoom: Restrict autoscale to visible spectrum area. Added missing images for documentation. Issue #773

sdrbase/dsp/spectrumvis.cpp

@@ -683,6 +683,15 @@ void SpectrumVis::feed(const SampleVector::const_iterator& cbegin, const SampleV
 	 m_mutex.unlock();
 }
 
+void SpectrumVis::getZoomedPSDCopy(std::vector<Real>& copy) const
+{
+    int fftMin = (m_frequencyZoomFactor == 1.0f) ?
+        0 : (m_frequencyZoomPos - (0.5f / m_frequencyZoomFactor)) * m_settings.m_fftSize;
+    int fftMax = (m_frequencyZoomFactor == 1.0f) ?
+        m_settings.m_fftSize : (m_frequencyZoomPos + (0.5f / m_frequencyZoomFactor)) * m_settings.m_fftSize;
+    copy.assign(m_psd.begin() + fftMin, m_psd.begin() + fftMax);
+}
+
 void SpectrumVis::start()
 {
     setRunning(true);

sdrbase/dsp/spectrumvis.h

@@ -147,7 +147,8 @@ public:
     const GLSpectrumSettings& getSettings() const { return m_settings; }
     Real getSpecMax() const { return m_specMax / m_powFFTDiv; }
     void getPowerSpectrumCopy(std::vector<Real>& copy) { copy.assign(m_powerSpectrum.begin(), m_powerSpectrum.end()); }
-    void getPSDCopy(std::vector<Real>& copy) { copy.assign(m_psd.begin(), m_psd.begin() + m_settings.m_fftSize); }
+    void getPSDCopy(std::vector<Real>& copy) const { copy.assign(m_psd.begin(), m_psd.begin() + m_settings.m_fftSize); }
+    void getZoomedPSDCopy(std::vector<Real>& copy) const;
 
 	virtual void feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end, bool positiveOnly);
     virtual void feed(const Complex *begin, unsigned int length); //!< direct FFT feed

sdrgui/gui/glspectrumgui.cpp

@@ -267,7 +267,7 @@ void GLSpectrumGUI::on_autoscale_clicked(bool checked)
     }
 
     std::vector<Real> psd;
-    m_spectrumVis->getPSDCopy(psd);
+    m_spectrumVis->getZoomedPSDCopy(psd);
     int avgRange = m_settings.m_fftSize / 32;
 
     if (psd.size() < (unsigned int) avgRange) {