ISI (InterSymbol Interference) Signal distortion caused by the overlap of symbols (i.e., the smallest units transmitted) in a digital transmission system. Intersymbol interference includes the overlap of bits in a purely digital transmission system, such as a fiber optic transmission system (FOTS), or sinusoidal waveforms in a digital system involving the modulation of a carrier waveform, such as a T-carrier or E-carrier system. See also pulse dispersion. 74570c09.qxd 9/11/07 12:22 PM Page 262 |