"to amplify the signal" means to make a weak or low-volume signal stronger or louder. It is a way to enhance or boost the power or strength of the message being conveyed. Full definition
By concentrating my works in a single place, I'm not making them unavailable to anyone; I'm just amplifying the signal of all those purchases and reader reactions. (hughhowey.com)
«A paper diagnostic for cancer: Low - cost urine test amplifies signals from growing tumors to detect disease.» (sciencedaily.com)
The protein Gab2 works like a multi-outlet power strip for proteins in a chain of signals: It can pass on a signal it receives to several enzymes at once and can also amplify the signal. (sciencedaily.com)