Patent ID: 7209746

Claim:
A transmission apparatus comprising: a master station for transmitting and receiving a video or audio transmission signal by utilizing a first minute-power wave, said transmission signal comprising slave station address information and master station receiving frequency information indicating a frequency at which a master station can receive a signal from a relay station; a slave station for transmitting and receiving a video or audio transmission signal utilizing a second minute-power wave; and a relay station located between the master station and the slave station, said master and slave stations located apart from each other by a distance longer than the reachable range of a first minute-power wave, wherein said relay station is for receiving a first minute-power signal (f 1 ) from modulating at the master station, modulating it to a different frequency (f 2 ), and transmitting the modulated first minute-power signal to the slave station; said relay station is for receiving from the master station, return frequency information (f 0 ) as part of a first minute-power signal, demodulating a portion of a second minute-power signal received from the slave station, modulating the demodulated portion at the master station return frequency (f 0 ), and transmitting the modulated portion of the second minute-power signal to the master station, thereby establishing a return transmission path between the relay station and the master station; said relay station is for transmitting information about a relay station receiving frequency at which the relay station receives a signal from the slave station; said slave station is for recognizing that a transmission signal is a signal directed to said slave station; and said slave station is for modulating and transmitting a response signal comprising video or audio information at said relay station receiving frequency, thereby establishing a transmission path between the master station and the slave station.