% build filter% sample ratefs = 6250;% cutoff frequencyfc = 1000;% build a 6th-order highpass Butterworth filter with a cutoff frequency of 300 Hz,[b a]=butter(2 ,fc/(fs/2),'high');

% show magnitude responsen = 512;[h,w] = freqz(b,a,[0:(fs/n/2):fs/2],fs);plot(w/1000,20*log10(abs(h)));ylabel('Magnitude(dB)')xlabel('Frequency(kHz)')title('Magnitude Response(dB)');grid on;