Windowed FIR Filter with Gain

The examples provided here use this signal:

$\cos(2\pi\times0.5t) + 0.2\sin(2\pi\times2.5t+0.1) + 0.2\sin(2\pi\times15.3t) + 0.1\sin(2\pi\times16.7t + 0.1) + 0.1\sin(2\pi\times23.45t+0.8)$

FIRWin2

Type 1 Filter

The parameters for this filter are as follows:

• Taps ⇨ 15
• Cutoff Frequency ⇨ [0Hz, 25Hz, 50Hz]
• Gains ⇨ [0.0, 1.0, 1.0]
• Sampling Frequency ⇨ 100Hz

Code

double samplingRate = 100;
double[] freqs = {0.0, 25, 50};
double[] gains = {0.0, 1.0, 1.0};
int taps = 15;

FIRWin2 fw2 = new FIRWin2(taps, samplingRate);
double[] outCoeffs = fw2.computeCoefficients(freqs, gains);
double[] filteredX = fw2.firfilter(outCoeffs, signal);

Type 2 Filter

The parameters for this filter are as follows:

• Taps ⇨ 10
• Cutoff Frequency ⇨ [0Hz, 25Hz, 50Hz]
• Gains ⇨ [1.0, 1.0, 0.0]
• Sampling Frequency ⇨ 100Hz

Code

double samplingRate = 100;
double[] freqs = {0.0, 25, 50};
double[] gains = {1.0, 1.0, 0.0};
int taps = 10;

FIRWin2 fw2 = new FIRWin2(taps, samplingRate);
double[] outCoeffs = fw2.computeCoefficients(freqs, gains);
double[] filteredX = fw2.firfilter(outCoeffs, signal);

Type 3 Filter

The parameters for this filter are as follows:

• Taps ⇨ 15
• Cutoff Frequency ⇨ [0Hz, 25Hz, 50Hz]
• Gains ⇨ [0.0, 1.0, 0.0]
• Sampling Frequency ⇨ 100Hz

Code

double samplingRate = 100;
double[] freqs = {0.0, 25, 50};
double[] gains = {0.0, 1.0, 0.0};
int taps = 15;

FIRWin2 fw2 = new FIRWin2(taps, samplingRate, true);
double[] outCoeffs = fw2.computeCoefficients(freqs, gains);
double[] filteredX = fw2.firfilter(outCoeffs, signal);

Type 4 Filter

The parameters for this filter are as follows:

• Taps ⇨ 10
• Cutoff Frequency ⇨ [0Hz, 25Hz, 50Hz]
• Gains ⇨ [0.0, 1.0, 1.0]
• Sampling Frequency ⇨ 100Hz

Code

double samplingRate = 100;
double[] freqs = {0.0, 25, 50};
double[] gains = {0.0, 1.0, 1.0};
int taps = 10;

FIRWin2 fw2 = new FIRWin2(taps, samplingRate, true);
double[] outCoeffs = fw2.computeCoefficients(freqs, gains);
double[] filteredX = fw2.firfilter(outCoeffs, signal);