I have designed this bandstop filter to a desired specification:
$\text{Stopband attenuation} = 40\,\text{dB}$ $\text{Passband ripple} = 2\,\text{dB}$ etc ...
I understand that the stopband ripple can be given by the following:
$$ \text{Stopband ripple} = −20\log_{10}(\delta_s) $$ $$ \Leftrightarrow 40 = −20\log_{10}(\delta_s) $$ $$\Leftrightarrow \delta_s=0.01$$
Where I am confused is how this value can be converted into $\text{dB}$ so that it can be compared to the stop-band ripple seen in the MATLAB simulation (which is in $\text{dB}$). $40\,\text{dB}$ is the stopband attenuation, not the stopband ripple (or is it?). the simulation is showing a stopband ripple of around $32\,\text{dB}$.... are the stopband attenuation and ripple with same ? What am I missing ?