ABSTRACT
Because the passband attenuation of first stage Half-Band filter should be determined by the the second stage Half-Band filter passband attenuation. The second stage Half-Band filter has been able to be fully finalized technical indicators. Therefore, we should design the second stage Half-Band filter first. The input signal sampling frequency of the Half-Band filter is 4 kHz, the sampling frequency of the output signal is 2 kHz and it is the last stage of the digital decimation filter, so the passband cutoff frequency, stopband start frequency and stopband attenuation are required to meet the overall requirements of the digital decimation filter. We set the Half-Band filter passband cutoff frequency 0.8 kHz, the transition zone from 0.8 kHz to 1.2 kHz, stopband attenuation is 120 dB. By Using FDATool toolbox in MATLAB software, we can design the Half-Band filter meet all the requirements.
