close all, clear all, clc
% Chebyshev I Notch Filter
SR = 10E3; % 10 kHz sample rate
SR2 = SR/2;
Fs = [1800 2200]; % Stopband: 1.8 kHz - 2.2 kHz
Fp = [1500 2500]; % Passband: 1.5 kHz - 2.5 kHz 
Wp = Fp/SR2;
Ws = Fs/SR2;
Rp = 0.5;
Rs = 30;
[N, Wn] = cheb1ord(Wp, Ws, Rp, Rs);
[B, A] = cheby1(N, Rp, Wn, 'stop');
[H, w] = freqz(B, A);
subplot(2,1,1), plot(w/pi*SR2, abs(H)), grid
subplot(2,1,2), plot(w/pi*SR2, angle(H)), grid