Just for reference, let us say we are talking of a Butterworth low pass filter.
What is the real usefulness of knowing the cutoff frequency value (-3 dB attenuation) for me, when I am interested in designing a filter that would pass UP TO xxx Hz with no attenuation, that is 0 dB?
For this particular case, why cutoff frequency is not expressed as the highest frequency point where attenuation is still 0 dB for that filter?
Other way of asking more or less the same: how can I know for the above filter what is the highest frequency that would pass without being attenuated?
Since we are here, could anyone, after answering that question, extend the concept to all filters?
What is the real usefulness of knowing the cutoff frequency value (-3 dB attenuation) for me, when I am interested in designing a filter that would pass UP TO xxx Hz with no attenuation, that is 0 dB?
For this particular case, why cutoff frequency is not expressed as the highest frequency point where attenuation is still 0 dB for that filter?
Other way of asking more or less the same: how can I know for the above filter what is the highest frequency that would pass without being attenuated?
Since we are here, could anyone, after answering that question, extend the concept to all filters?