US Patent 7583749 Digital data transmitting apparatus

A transmitting circuit 10 converts transmission data to a multilevel analog signal suitable for transmission. The multilevel analog signal is output to a cable 21 via an amplifier and a hybrid circuit 12. In the transmitting circuit 10, a waveform which compensates waveform deterioration at the cable 21 is generated. A reception signal from the cable 21 is input to a mixer 14 via the hybrid circuit 12 and an amplifier 13. The mixer 14 mixes the reception signal and a cancel signal output from a cancel signal generation circuit 17 so as to remove undesired signals. In a receiving circuit 15, the signal output from the mixer 14 is sampled by use of a plurality of sample-hold circuits, and subjected to analog sum-of-product computation which is performed by a matrix circuit for distortion compensation. Subsequently, the sampled signals are converted to digital signals. The digital signals are collectively subjected to processing such as parallel-serial conversion, whereby reception data and an evaluation signal are obtained. An adjustment control circuit 18 includes a CPU, and adjusts the respective circuits on the basis of the evaluation signal such that data can be correctly transmitted and received.