SYSTEM FOR TRANSMITTING, RECEIVING AND DECODING MULTILEVEL SIGNALS

Apparatus for automatically equalizing a multilevel signal transmission system is disclosed for transmitting a signal in the form of a multilevel signal. In particular, an automatic equalization system is adapted to provide a reference level signal having fewer levels than the multilevel signal; predetermined level values are inserted in a train of multilevel signals at predetermined time intervals for the purpose of correct detection of the multilevel from the received signal waveform although intersymbol interference is introduced in a received multilevel signal owing to linear distortion of the transmission line such as amplitude distortion, phase distortion or the like. In the receiving side, the intersymbol interference with the reference level signal is detected and then an adjustment device of an automatic equalizer is controlled to correct intersymbol interference, with the result that the intersymbol interference in the multilevel signal to be transmitted is corrected.