TUGAS PRAKTIKUM V

METODE ANALISIS GEOFISIKA II

“PROSES FILTER FIR (LOWPASS, BANDPASS, DAN HIGHPASS) DATA ANGIN”

FAKULTAS MATEMATIKA dan ILMU PENGETAHUAN ALAMUNIVERSITAS GADJAH MADA

YOGYAKARTA2009

load windpowersec.datyear=windpowersec(:,1); x=windpowersec(:,1); y=windpowersec(:,2);figure;stem(x,y,'ro');xlabel('Time (seconds)'); ylabel('Powerout of Wind'); title ({'Grafik Kekuatan Angin 09-02-2009' ; 'Pukul 18.00 - 19.00'}); xi=1:1:232; %Banyak datafor i=1:232 h(i,1)=xi(i); h(i,2)=y(i);end %Baseline Correctionr=mean(y);yb=y-r;figure;plot(x,yb,'r-');xlabel('Time (seconds)'); ylabel('Powerout of Wind'); title ({'Grafik Kekuatan Angin 09-02-2009 Pukul 18.00 - 19.00';'Baseline Correction'});for i=1:232 hbase(i,1)=xi(i); hbase(i,2)=y(i);end %Frekuensi Sampling dan Nyquist%dt = 15 Secondsfsamp=0.067;fnyq=.5*fsamp; %Proses FFTYb=fft(yb); n=length(Yb);power = abs(Yb(1:n/2)).^2;hold off; freq = (1:n/2)/(n/2)*fnyq;figure; plot(freq,power);xlabel('Cycle/Seconds'); ylabel('Power spectral'); title ('Periodogram'); % A. FILTER LOW PASS%========================%Tanggap ImpulseFL = 0.02; %frekuensi cut-off bawahW0=FL/fnyq; for i=1:1:n; LP(i)=2*W0*(sin((i)*pi*W0)/((i)*pi*W0));end;for i=1:n; hL(i)=LP(n-i+1); hL(n+i)=LP(i);end;figure;plot(hL(1:2*n),'b');

title('Tanggapan Impulse Low Pass Filter'); xlabel('n');ylabel('h(n)'); %Zero-Phase ResponseLP1 = abs(fft(LP));for i = 1:1:n/2 LPF(i) = LP1(n/2-i+1);endfigure;plot(freq.*30*pi,LPF,'r');title('Zero-Phase Response'); xlabel('Normalized Frekuensi');ylabel('H(f)'); %Filtering gelombang dengan LPF (Frekuensi Domain)LF = LPF'.*power;figure; plot(freq,LF,'r');title({'Filtering Data dengan Low Pass Filter';'Frekuensi Domain'}); xlabel('Frekuensi (Hz)');ylabel('Amplitude'); %Filtering gelombang dengan LPF (Time Domain)LT = cconv(yb',LP,232);figure; plot(x,LT,'r');title({'Filtering Data dengan Low Pass Filter';'Time Domain'}); xlabel('Time (Seconds)');ylabel('Powerout of Wind'); % B. FILTER HIGH PASS%========================%Tanggap ImpulseFH = 0.01; %frekuensi cut-off atasW1=FH/fnyq; for k=1:1:n; HP(k)=-2*W1*(sin((k)*pi*W1)/((k)*pi*W1));end;for k=1:n; hH(k)=HP(n-k+1); hH(n+k)=HP(k);end;figure;plot(hH(1:2*n),'b'); title('Tanggapan Impulse High Pass Filter'); xlabel('n');ylabel('h(n)'); %Zero-Phase ResponseHP1 = abs(fft(HP));for k = 1:1:n/2 HPF(k) = HP1(k+n/2);endfigure;plot(freq.*30*pi,HPF,'r');title('Zero-Phase Response'); xlabel('Normalized Frekuensi');ylabel('H(f)'); %Filtering gelombang dengan HPF (Frekuensi Domain)HF = HPF'.*power;figure; plot(freq,HF,'r');title({'Filtering Data dengan High Pass Filter';'Frekuensi Domain'}); xlabel('Frekuensi (Hz)');ylabel('Amplitude'); %Filtering gelombang dengan HPF (Time Domain)HT = cconv(yb',HP,232);figure; plot(x,HT,'r');title({'Filtering Data dengan High Pass Filter';'Time Domain'}); xlabel('Time (Seconds)');ylabel('Powerout of Wind');

% C. FILTER BAND PASS%========================%Tanggap ImpulseFL = 0.01;FH = 0.024;W2 = FH/fnyq;W3 = FL/fnyq; for z=1:1:n; BP(z)=2/(z*pi)*(sin((z)*pi*W2)-sin((z)*pi*W3));end;for z=1:n; hB(z)=BP(n-z+1); hB(n+z)=BP(z);end;figure;plot(hB(1:2*n),'b'); title('Tanggapan Impulse Band Pass Filter'); xlabel('n');ylabel('h(n)'); %Zero-Phase ResponseBP1 = abs(fft(BP));for i = 1:1:n/2 BPF(i) = BP1(i);endfigure;plot(freq.*30*pi,BPF,'r');title('Zero-Phase Response'); xlabel('Normalized Frekuensi');ylabel('H(f)'); %Filtering gelombang dengan BPF (Frekuensi Domain)BF = BPF'.*power;figure; plot(freq,BF,'r');title({'Filtering Data dengan Band Pass Filter';'Frekuensi Domain'}); xlabel('Frekuensi (Hz)');ylabel('Amplitude'); %Filtering gelombang dengan BPF (Time Domain)BT = cconv(yb',BP,232);figure; plot(x,BT,'r');title({'Filtering Data dengan Band Pass Filter';'Time Domain'}); xlabel('Time (Seconds)');ylabel('Powerout of Wind');

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Grafik Kekuatan Angin 09-02-2009Pukul 18.00 - 19.00

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Grafik Kekuatan Angin 09-02-2009 Pukul 18.00 - 19.00Baseline Correction

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X: 0.0005776Y: 9.91e+006

Cycle/Seconds

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Periodogram

A. LOWPASS FILTER (FIR)

Panjang Filter (N) yang digunakan samadengan panjang data, 232Dengan frekuensi cut-off atas 0.02 HzFrekuensi nyquist 0.033 Hz

0 50 100 150 200 250 300 350 400 450-0.2

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0.7Tanggapan Impulse Low Pass Filter

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TANGGAPAN IMPULSE LOWPASS DOMAIN TIME

0 0.5 1 1.5 2 2.5 30.4

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2Zero-Phase Response

Normalized Frekuensi

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ZERO-PHASE RESPONSE LOWPASS(Hingga PI)

0 0.005 0.01 0.015 0.02 0.025 0.030

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6Filtering Data dengan Low Pass Filter

Frekuensi Domain

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HASIL FILTERING DATA ANGIN PADA DOMAIN FREKUENSI(DIKALI HASIL ZERO-RESPONSE)

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HASIL FILTERING DATA ANGIN PADA DOMAIN TIME(HASIL KONVOLUSI CIRCULAR DATA DENGAN TANGGAP IMPULSE)

B. HIGHPASS FILTER (FIR)

Panjang Filter (N) yang digunakan samadengan panjang data, 232Dengan frekuensi cut-off bawah 0.01 HzFrekuensi nyquist 0.033 Hz

0 50 100 150 200 250 300 350 400 450-0.6

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0.2Tanggapan Impulse High Pass Filter

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TANGGAPAN IMPULSE HIGHPASS DOMAIN TIME

0 0.5 1 1.5 2 2.5 30.2

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1.8Zero-Phase Response

Normalized Frekuensi

H(f

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ZERO-PHASE RESPONSE HIGHPASS(Hingga PI)

0 0.005 0.01 0.015 0.02 0.025 0.03 0.0350

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Frekuensi Domain

Frekuensi (Hz)

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HASIL FILTERING DATA ANGIN PADA DOMAIN FREKUENSI(DIKALI HASIL ZERO-RESPONSE)

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Filtering Data dengan High Pass FilterTime Domain

Time (Seconds)

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HASIL FILTERING DATA ANGIN PADA DOMAIN TIME(HASIL KONVOLUSI CIRCULAR DATA DENGAN TANGGAP IMPULSE)

C. BANDPASS FILTER (FIR)

Panjang Filter (N) yang digunakan samadengan panjang data, 232Dengan frekuensi cut-off atas 0.01 Hz, dan frekuensi cut-off bawah 0.025 HzFrekuensi nyquist 0.033 Hz

0 50 100 150 200 250 300 350 400 450-0.7

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0.2Tanggapan Impulse Band Pass Filter

n

h(n)

TANGGAPAN IMPULSE BANDPASS DOMAIN TIME

0 0.5 1 1.5 2 2.5 30.4

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1.4

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2Zero-Phase Response

Normalized Frekuensi

H(f

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ZERO-PHASE RESPONSE BANDPASS(Hingga PI)

0 0.005 0.01 0.015 0.02 0.025 0.03 0.0350

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6Filtering Data dengan Band Pass Filter

Frekuensi Domain

Frekuensi (Hz)

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HASIL FILTERING DATA ANGIN PADA DOMAIN FREKUENSI(DIKALI HASIL ZERO-RESPONSE)

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Filtering Data dengan Band Pass FilterTime Domain

Time (Seconds)

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HASIL FILTERING DATA ANGIN PADA DOMAIN TIME(HASIL KONVOLUSI CIRCULAR DATA DENGAN TANGGAP IMPULSE)