An analog signal processor is used to quickly process signals that can be too complex to handle any other way. A comparator is used to offer level triggers correct down to microvolts with reaction times in the picoseconds. Analog filters offer anti-aliasing in sampled value systems as inputs and outputs, and can be used as pre-filters in audio and communications. Analog multipliers and dividers are used to offer brief gain control, radiometric function, or continuous energy measurement, with surprising accuracy. Over-voltage protection applications can protect the front-end of analog transmission/receiver systems, multiplexers. Amplification and filtering for noise removal are the main feature of analog signal processing.