Abstract:
A radio wave sensing apparatus capable of performing carrier sense of a spectrum−spread radio wave with a simple configuration. An information signal S1 is multiplied by a spreading symbol so that a band is spread to generate a spread information signal S7 and combine the spread information signal S7 with an indicator signal S10 of a predetermined band so as to be transmitted as a radio wave. Furthermore, a signal component of a predetermined band is extracted from the received radio wave, thereby isolating an indicator signal S11. According to the reception power of the isolated indicator signal S11, presence/absence of a radio wave is detected. When the presence of a radio wave is detected, transmission of a radio wave is stopped.