PURPOSE: To simplify the configuration of a hardware and further to suppress carrier frequencies to one frequency by constituting the plural filter groups of a MODEM with transform multiplexer(TMUX) or transform demultiplexer(TDMUX).
CONSTITUTION: A modulator input signal is divided into plural channels and converted to a time division multiplex(TDM) signal by a demultiplexer(DMUX) 52. On the other hand, this signal is further converted to a frequency division multiplex(FDM) signal by a transform multiplexer(TMUX) 53, and a carrier signal is modulated with the FDM signal by a modulator 54. Thus, a plural carrier modulator 50 is constituted. Therefore, the modulator and a carrier signal generator, etc., are reduced in comparison with the conventional configuration, and the amount of the hardware can be reduced. Concerning even a plural carriers modulator 51, it can be similarly composed of a demodulator 55, TDMUX 56 and MUX 57.
OTA MASAAKI
TSUKAGOSHI KAZUAKI
ADACHI MASARU
HITACHI ELECTRONICS
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