脉冲频率为1khz，周期10ms，N=1的正弦脉冲串。
signal x=10*sin(2*pi*f1*t+angle1)+sin(2*pi*f2*t+angle2)+215原始去直流偏移10 5magnitude0-5-10-15 00.020.040.060.080.1time/s0.120.140.160.180.2
butterworth低通滤波器频响曲线 02阶4阶-10magnitude/db-20-30-40-50-60 00.20.40.60.81f/hz1.21.41.61.8x 1024两次鱼叫的频谱353025magnitude2015105005001000150020002500f/hz30003500400045005000
滤波前后的频谱12001000800magnitude60040020000100200300400500f/hz6007008009001000
低通滤波后的时域波形20magnitude100-10-2000.0050.010.0150.02t/s高通滤波后的时域波形100.0250.030.0350.040.045magnitude50-500.20.40.60.81t/s1.21.41.61.8x 102-3
