Abstract: An optical radio communication system comprising a first light transmitting system and a second light transmitting system. Each of said first and second light transmitting system comprising a transmitting means and a receiving means. Said transmitting means comprising a light emitting element positioned in a region including and surrounding a focal point of a first parabolic reflector for emitting light beams, said first parabolic reflector having an inner reflective surface for reflecting said light beams emitted from said light emitting element, and a means for driving said light emitting element with a signal to be transmitted.

Abstract: An optical radio system includes a host device, an end device, and a repeater. The host device and the end device communicate with each other via the repeater by use of optical radio. The repeater includes a section for receiving a first light signal from one of the host device and the end device, a section for converting the received first light signal into a first electric signal, a section for frequency-converting the first electric signal into a second electric signal, and a section for generating a second light signal in response to the second electric signal and transmitting the generated second light signal. The repeater also includes a section for demodulating one of the first electric signal and the second electric signal into a baseband signal, a section for detecting a quality of the baseband signal, and a section for enabling transmission of the second light signal only when the detected quality of the baseband signal is equal to or greater than a predetermined quality.