Quadrature modulator for TDMA/TDD radio communication apparatus

DETAILED DESCRIPTION It is therefore an object of the present invention to provide a radio telephone apparatus of the TDMA/TDD system type capable of completely solving the problem of the occurrence of the channel interference in the same housing, thereby avoiding the problem of the prior art.
In accordance with an aspect of the present invention, there is provided a radio telephone apparatus for conducting communications in a TDMA/TDD system using carriers, wherein the carrier in a signal transmission has a frequency different from that of the carrier in a signal reception.
According to another aspect of the present invention, there is provided a radio telephone apparatus having transmitting means and receiving means for conducting communications, wherein the transmitting means includes a frequency divider quadrature modulator (at times referred to herein as a frequency division orthogonal modulator).
The modulator includes an amplifier for receiving as input thereto a local signal and producing therefrom an intermediate frequency, the amplifier amplifying a carrier frequency with which the intermediate frequency is mixed, and a control terminal for stopping the output of the intermediate frequency.
According to still another aspect of the present invention, there is provided a radio communication system in which a plurality of radio stations share thereamong a frequency with respect to time for establishing a time-division multiplex connection therebetween and conduct time-division bidirectional transmissions by use of channels of the frequency respectively assigned thereto.
Each of the radio station includes a transmitting section having a frequency division modulator and a transmission amplifier, a receiving section having a demodulator, and an antenna change-over switch for connecting an antenna to either one of the transmitting section and the receiving section.
The radio station sets, in a signal transmission state, the switch to a side of the transmitting section and setting the frequency divider quadrature modulator of the transmitting section to an operative state, thereby emitting a transmission wave