www.pudn.com > voiceprocessingtoolbox.rar > fft5.m

% Use the Blackman window on the sinusoid data 
N=64; 
zpf=8; 
xw = [w .* cos(2*pi*n*f*T),zeros(1,(zpf-1)*N)]; % windowed, zero-padded data 
X = fft(xw);                                    % Smoothed, interpolated spectrum 
 
% Plot time data 
subplot(2,1,1); 
plot(xw);         
title('Windowed, Zero-Padded, Sampled Sinusoid'); 
xlabel('Time (samples)'); ylabel('Amplitude'); 
text(-50,1,'a)') 
 
% Plot spectral magnitude in the best way 
spec = 10*log10(conj(X).*X);  % Spectral magnitude in dB 
spec = max(spec,-60*ones(1,nfft)); % clip to -60 dB 
subplot(2,1,2); 
plot(fninf,fftshift(spec),'-'); axis([-0.5,0.5,-60,40]); grid; 
title('Smoothed, Interpolated, Spectral Magnitude (dB)');  
xlabel('Normalized Frequency (cycles per sample))');  
ylabel('Magnitude (dB)');