Abstract: An optical space communication apparatus such as an optical space communication transceiver comprises a plurality of modules which can be coupled and separated from each other. In the modules, the positions of optical elements are adjusted beforehand with respect to coupling reference portions of the modules which are to constitute a common reference at the time of coupling of the modules. As a result, the modules can be automatically positioned relative to one another at the time of coupling therebetween. Alternatively, one of the plurality of modules may have a stand reference portion having a predetermined positional relationship with its optical element and its coupling reference portion. The stand reference portion is coupled to the reference portion of the stand whose angle can be adjusted to thereby constitute the common reference.

Abstract: There are provided a communication system and an apparatus for modulating a communication signal into a chirp signal and executing the communication. In the system, a signal to be transmitted is input, a predetermined analog pattern signal is added to the input signal and is pulse position modulated, the modulated signal is converted into the chirp signal, and the chirp signal is output onto a transmission path. The converted chirp signal can be also converted into an optical signal and the optical signal can be also output onto the transmission path. After the analog or digital input signal was pulse position modulated, by converting the modulated signal into the chirp signal, the analog signal can be also transmitted and received as a chirp signal. Thus, the communication reliability can be assured without being influenced by disturbance noises or irrespective of a limitation of a transmission electric power of the transmission path.

Abstract: There are provided digital communicating method and apparatus for modulating digital signals into chirp signals and performing the communication. In this method, pulses indicative of digital signals of codes "1" and "0" are modulated, the modulated pulse signals are converted into chirp signals, the chirp signals are converted into the optical signals and output as transmission signals, and the digital signals are input and the pulses based thereon are generated. A wave of a predetermined frequency is multiplied by the pulses indicative of "1" and "0" of the digital signals and the modulation is executed. The communication signals can be converted into the chirp signals by the chirp conversion elements using the surface acoustic wave-dispersive delay lines having different converting characteristics by the simple construction.

Abstract: A light signal receiver comprises a plurality of photo-sensors, a detector for detecting signal levels of light signals sensed by the photo-sensors, a selector for selecting those photo-sensors which result in a proper output signal, and output means for combining the signals sensed by the selected photo-sensors to produce the output signal.