A comparison of fixed-point and floating-point realization of digital filter

The author deals with the problem of designing FIR (finite impulse response) raised-cosine filters, starting from the frequency specification, that is, from the transfer function C^α( f, p, T). Both the ISI (intersymbol interference) of the cascade of transmitter and receiver filters and the behavior of the stopband (amplitude of the side lobes) are considered in comparing the filter design methods. Three design methods are considered: time-domain method, based on the inverse Fourier transform of C^α(f, p, T); a time domain method with windows, based on the inverse Fourier transform of C ^α(f, p, T), modified by a Hamming window, and frequency sampling based on DFT (discrete Fourier transform) methods