MATLAB: IIR Bandstop (Notch) Filter design

Question

Im new to filter design and I'd like to design an IIR bandstop filter with the following conditions:

2.01: 200 Hz,

2.02: 15 Hz bandwidth,

2.03: 30 dB depth,

Answer 1

I have absolutely no idea what ‘2.01’, ‘2.02’ and ‘2.03’mean.

Here is a prototype bandstop filter design that you can change to produce the filter you want:

Fs = 900;                                                           % Sampling Frequency
Fn = Fs/2;                                                          % Nyquist Frequency
Wp = [48 52]/Fn;                                                    % Stopband Frequency (Normalised)
Ws = [0.9 1.1].*Wp;                                                 % Passband Frequency (Normalised)
Rp =  1;                                                            % Passband Ripple
Rs = 90;                                                            % Passband Ripple (Attenuation)
[n,Wp] = ellipord(Wp,Ws,Rp,Rs);                                     % Elliptic Order Calculation
[z,p,k] = ellip(n,Rp,Rs,Wp,'stop');                                 % Elliptic Filter Design: Zero-Pole-Gain 
[sos,g] = zp2sos(z,p,k);                                            % Second-Order Section For Stability
figure
freqz(sos, 2^18, Fs)                                                % Filter Bode Plot
set(subplot(2,1,1), 'XLim',[0 Fs/5])                                % Optional

set(subplot(2,1,2), 'XLim',[0 Fs/5])                                % Optional
% signal_filt = filtfilt(sos, g, signal);                             % Filter Signal

Un-comment the filtfilt line to filter your signal.