signal processing - How to specify amplitude threshold in a filter in MatLab -

hi wanted clarification on how specify amplitude threshold on ellip filter.

this have done far

fmin  = 20;  % minimum passband frequency in hz (high gamma) fmax  = 30;  % maximum passband frequency in hz (high gamma) rs    = 20; % stopband attenuation in db rp    = 1;  % passband ripples in db    % high gamma band  [order, wn] = ellipord([fmin/(fs/2), fmax/(fs/2)], [(fmin-1)/(fs/2), (fmax+1)/(fs/2)], rp, rs); [b,a] = ellip(order, rp, rs, [fmin/(fs/2), fmax/(fs/2)]); 

i new correct me assume rs , rp amplitude thresholds, allowed through? or have else. after averaging out data remove common noise , using ranksum energy data, plot looks image.

as can see there massive spike , reduce threshold spikes can ignore.

rp , rs represent passband ripple , stopband attenuation in frequency domain respectively. plotting frequency response of filter freqz(b,a) give plot looks like:

as can see response in passband between specified fmin (20hz) , fmax (30hz) varies little. variation passband ripple rp.

outside passband (below 20hz , above 30hz), response varies not exceed -20db. stopband attenuation rs.

so, parameters not represent threshold time-domain amplitude, although may able reduce little overall amplitude of large impulses increasing stopband attenuation rs. note better improvement of signal need take account input desired output characteristics.