PURPOSE: To realize a signal transmission/reception system by a CATV line in which massive information is easily sent.

CONSTITUTION: A time division multiplexer 1 multiplexes input digital signals of lots of channels into time division multiplex signals of n-channels, 22k of multi-value orthogonal amplitude modulation is applied to a carrier by using a signal of each of n-channel time division signals to generate n-channel QAM signals, the QAM signal at every channel and each of m-channel television video signals are subjected to frequency multiplexing and the result is sent through a CATV line. The frequency multiplex signal is demultiplexed into each of n-channel QAM signals and each of m-channel television video signals, each of the n-channel QAM signals is subjected to QAM demodulation respectively to generated an n-channel time division multiplex signals and the n-channel time division multiplex signals are subjected to time division demultiplexing to generate the original lots of channel digital signals.