Optimal design of prefilters for binary FSK discriminators

Prefilters are derived for delay-line discriminators for FSK systems which allow these simple demodulators to give optimum, or matched filter performance. Filters are presented which allow the demodulator to give optimum performance even when the tone spacing is a multiple of the minimum orthogonal spacing. Finally, an architecture is suggested that incorporates a tapped-delay-line to synthesise these prefilters.