1．找点一段心电信号，画出信号时域波形和频谱图；

2. 利用MATLAB中的随机函数产生噪声加入到心电信号中，使心电信号被污染，读出污染后的号并画出对应信号的时域波形和频谱图；

3．用双线性变换法设计一个Butterworth带通滤波器，输出所设计的滤波器的阶次，分子、分母多项式的系数，画出滤波器的频率响应（幅频响应和相频响应）曲线；（也可以根据自己需要设置滤波器性能指标）

带通通滤波器设计性能指标：fs1=10Hz, fp1=20Hz, fp1=1000Hz, fs2=1200Hz, ap=18dB,as=3dB

4．用滤波器对含噪声的心电信号进行滤波，画出滤波以后信号的时域波形和频谱；

5．比较滤波前后信号变化；

-1. Find a ECG, draw time-domain signal waveform and frequency spectrum　

2. Using MATLAB random function in the noise added to the ECG, so that the contaminated ECG signals, read out the contamination of the number and draw the corresponding time domain waveform and frequency spectrum　

3. Bilinear transformation method used to design a Butterworth bandpass filter, the output of the order of the filter design, numerator, denominator polynomial coefficients, draw the filter frequency response (amplitude frequency response and phase frequency response) curve　 (you can also set filters based on their performance needs)

Filter design with all the performance indicators: fs1 = 10Hz, fp1 = 20Hz, fp1 = 1000Hz, fs2 = 1200Hz, ap = 18dB, as = 3dB

4. Filters for ECG signal with noise filtering, after filtering the signal to draw the time-domain waveform and frequency spectrum　

5. Compare signal change before and after filtering