Abstract: There are disclosed a transmission device and a reception device having a high secrecy making it difficult to wire tap by a third device. The transmission device includes a modulation section which can be modulated by a plurality of modulation methods and a transmission section which can transmit a radio signal by using a plurality of carrier frequencies. Moreover, the reception device includes a demodulation device which can demodulate by using a plurality of demodulation methods and a reception section which can receive a radio signal by using a plurality of carrier frequencies. The transmission communication method or the reception communication method is changed as the time elapses by changing the combination of the modulation method or demodulation method and the carrier frequency, thereby transmitting or receiving data.

Abstract: The present invention avoids distortion in a radio frequency device due to a received RF signal which has a voltage strength that is too high. The invention comprises a radio frequency signal attenutation circuitry, a radio frequency signal processing circuitry, intermediate frequency processing circuitry, and a gain controlling unit. The gain controlling unit is configured to output a control signal to the radio frequency signal attenuation circuitry and intermediate frequency processing circuitry. The radio frequency signal attenuation circuitry is configured to attenuate a radio frequency signal prior to being processed by radio frequency processing circuitry and intermediate frequency processing circuitry. Accordingly, saturation in the radio frequency signal processing circuitry and intermediate frequency processing circuitry is avoided.

Abstract: Upon receiving an FM multiplex broadcasting wave carrying audible information and supplemental visible information, an FM radio receiver equipped with a display unit audibly outputs the audible information and displays the supplemental visible information on the display unit. When the FM radio receiver receives the supplemental visible information while the receiver is not in a reproduction mode, the received supplemental visible information is stored in a reproduction buffer. When the FM radio receiver is set to the reproduction mode, the supplemental visible information stored in the reproduction buffer is displayed on the display unit.