信道化发射信号仿真实验，2.　　设计滤波器
应用Parks-McClellan optimal FIR filter order estimation设计滤波器，
参数：
内插I=16
内插前采样率50Hz
滤波器通带截止频率16Hz, 阻带起始频率25Hz；通带和阻带期望的幅度分别为1和0，起伏为1dB和40dB；
利用Parks-McClellan方法得到的频率向量fo，幅度向量ao和权值w设计最终使用的滤波器系数（可以使用remez方法，得到指定阶数的滤波器系数）。
显然，滤波器系数个数应为16的整数倍(Emulation experiment of channelized emission signal, 2. design filter
Using Parks-McClellan optimal FIR filter order estimation to design a filter,
Parameters:
Interpolating I=16
Pre interpolation rate 50Hz
The pass band cut-off frequency is 16Hz, and the band initiation frequency is 25Hz; the expected amplitude of the passband and stopband is 1 and 0, respectively, which fluctuate to 1dB and 40dB.
The frequency coefficients fo, amplitude vector AO and weight W obtained by the Parks-McClellan method are used to design the final filter coefficients (Remez coefficients can be used to get the filter coefficients of the specified order).
Obviously, the number of filter coefficients should be an integer multiple of 16.)