Before revision: Digital RTAs use digital sampling technology and microprocessor based digital signal processing to perform necessary calculations, such as Fast Fourier Transforms , to perform the measurements and thus do not need analog hardware filters to isolate each frequency band.
After revision: Digital RTAs use digital sampling technology and microprocessor based digital signal processing to perform necessary calculations, such as fast Fourier transforms , to perform the measurements and thus do not need analog hardware filters to isolate each frequency band.