Matched swept-frequency digital modulation for binary signaling in inhomogeneous dispersive media

A digital modulation technique which is most suitable for binary signaling through inhomogeneous dispersive media is introduced. Space-time rays are used to synthesize frequency-modulated input pulses that are either compressed in the medium with enhanced output or dispersed in the medium with widely spread output. The synthesized binary signals are shown to be in the form of swept-frequency signals which are matched to the dispersive properties of the medium. For media with quadratic phase functions, or under narrow-band conditions, the matched binary signals are linearly frequency modulated (chirp) with sweep rates that are related to the medium dispersion. The medium response to the matched chirp-modulated signals is investigated in detail. Conditions for the enhancement of the performance of the proposed modulation technique due to the available bandwidth are also discussed.