Merge pull request #24 from Dantali0n/master

New function to perform DC removal from sample data

README.md

@@ -56,6 +56,9 @@ Destructor
 * **Compute**(double *vReal, double *vImag, uint16_t samples, uint8_t power, uint8_t dir);
 * **Compute**(uint8_t dir);
 Calcuates the Fast Fourier Transform.
+* **DCRemoval**(double *vData, uint16_t samples);
+* **DCRemoval**();
+Removes the DC component from the sample data.
 * **MajorPeak**(double *vD, uint16_t samples, double samplingFrequency);
 * **MajorPeak**();
 Looks for and returns the frequency of the biggest spike in the analyzed signal.

keywords.txt

@@ -14,6 +14,7 @@ arduinoFFT	KEYWORD1
 
 ComplexToMagnitude	KEYWORD2
 Compute	KEYWORD2
+DCRemoval	KEYWORD2
 Windowing	KEYWORD2
 Exponent	KEYWORD2
 Revision	KEYWORD2

src/arduinoFFT.cpp

@@ -177,6 +177,39 @@ void arduinoFFT::ComplexToMagnitude(double *vReal, double *vImag, uint16_t sampl
 	}
 }
 
+void arduinoFFT::DCRemoval()
+{
+	// calculate the mean of vData
+	double mean = 0;
+	for (uint16_t i = 1; i < ((this->_samples >> 1) + 1); i++)
+	{
+		mean += this->_vReal[i];
+	}
+	mean /= this->_samples;
+	// Subtract the mean from vData
+	for (uint16_t i = 1; i < ((this->_samples >> 1) + 1); i++)
+	{
+		this->_vReal[i] -= mean;
+	}
+}
+
+void arduinoFFT::DCRemoval(double *vData, uint16_t samples)
+{
+	// calculate the mean of vData
+	#warning("This method is deprecated and will be removed on future revisions.")
+	double mean = 0;
+	for (uint16_t i = 1; i < ((samples >> 1) + 1); i++)
+	{
+		mean += vData[i];
+	}
+	mean /= samples;
+	// Subtract the mean from vData
+	for (uint16_t i = 1; i < ((samples >> 1) + 1); i++)
+	{
+		vData[i] -= mean;
+	}
+}
+
 void arduinoFFT::Windowing(uint8_t windowType, uint8_t dir)
 {// Weighing factors are computed once before multiple use of FFT
 // The weighing function is symetric; half the weighs are recorded

src/arduinoFFT.h

@@ -72,10 +72,12 @@ public:
 	void ComplexToMagnitude(double *vReal, double *vImag, uint16_t samples);
 	void Compute(double *vReal, double *vImag, uint16_t samples, uint8_t dir);
 	void Compute(double *vReal, double *vImag, uint16_t samples, uint8_t power, uint8_t dir);
+	void DCRemoval(double *vData, uint16_t samples);
 	double MajorPeak(double *vD, uint16_t samples, double samplingFrequency);
 	void Windowing(double *vData, uint16_t samples, uint8_t windowType, uint8_t dir);
 	void ComplexToMagnitude();
 	void Compute(uint8_t dir);
+	void DCRemoval();
 	double MajorPeak();
 	void Windowing(uint8_t windowType, uint8_t dir);