Multibit amplitude and phase modulation transceiver for lan

Abstract

A transceiver for a LAN is capable of communicating multiple bits per signal element to increase the data throughput of the LAN. The transceiver includes a transmitter which receives a multiple bit digital input value originating at a node of the LAN at which the transceiver is present. The transmitter converts the multiple bit digital input signal into a pulse-like analog signal which is amplitude and phase modulated. A receiver of a transceiver at a receiving node the transmitted analog signal converts its amplitude and phase into a corresponding multiple bit digital output value. A time-domain filter of the receiver creates a primary signal from the received analog signal. To sample the primary signal at its maximum amplitude point, a derivative of the primary signal waveform is used to establish the zero derivative point at which the primary signal attains its maximum amplitude, and to establish a fixed sampling point for subsequent signals. The sampling point is synchronized in phase with the stream of received analog signals. The residual intersymbol interference (ISI) effect of preceding signals on the LAN medium is eliminated prior to converting the primary signal to the digital value. To adjust and compensate for attenuation and amplification created by the LAN medium, the signal values are normalized.