Implement dc-remove option.

ecmcPlugin_FFT-loc/ecmcPlugin_FFTApp/src/ecmcFFT.cpp

@@ -284,6 +284,7 @@ void ecmcFFT::dataUpdatedCallback(uint8_t*       data,
       updateStatus(CALC);
 
       // **** Breakout to sperate low prio work thread below
+      removeDCOffset();
       calcFFT();      // FFT cacluation
       scaleFFT();     // Scale FFT
       calcFFTAmp();   // Calculate amplitude from complex 
@@ -397,6 +398,23 @@ void ecmcFFT::calcFFTAmp() {
   }
 }
 
+void ecmcFFT::removeDCOffset() {
+  if(!cfgDcRemove_) {
+    return;
+  }
+
+  // calc average of raw data
+  double sum = 0;
+  for(unsigned int i = 0; i < cfgNfft_; ++i ) {
+    sum += dataBuffer_[i];
+  }
+  double avg = sum / ((double)cfgNfft_);
+  for(unsigned int i = 0; i < cfgNfft_; ++i ) {
+    dataBuffer_[i]-=avg;
+  }
+}
+
+
 void ecmcFFT::printEcDataArray(uint8_t*       data, 
                                size_t         size,
                                ecmcEcDataType dt,

ecmcPlugin_FFT-loc/ecmcPlugin_FFTApp/src/ecmcFFT.h

@@ -56,6 +56,7 @@ class ecmcFFT {
   void                  calcFFT();
   void                  scaleFFT();
   void                  calcFFTAmp();
+  void                  removeDCOffset();
   void                  initAsyn();
   void                  updateStatus(FFT_STATUS status);  // Also updates asynparam
   static int            dataTypeSupported(ecmcEcDataType dt);