matlab下实现降噪，功率谱计算。％程序中设定采样点数为256个，采样频率为10000hz，

％输入信号为随机噪声和两个正弦的合成信号

％设定的滤波器的截止频率为3500hz

％通过挈比雪肤滤波器，运行程序，比较滤波前后的频域波形

％滤波去除了高频信号-matlab achieve noise reduction, power spectrum calculation.　Sampling procedure set for 256 points, the sampling frequency of 10000hz, input signal for the random noise and the two sinusoidal signals synthetic filter set a cut-off frequency 3500hz manner than through the filter雪肤, run procedures, compared before and after filtering in frequency domain waveforms filtering in addition to high-frequency signals