Abstract: Since a sampling frequency of RRU is always constant, A/D conversion may be performed with a sampling frequency higher than necessary with respect to a frequency band width of a radio signal. A sampling frequency change function, and the sampling frequency is reduced in a range where a aliasing component does not deteriorate signal quality of a desired signal component when the sampling frequency is decreased, based on radio band allocation information, or signal transmission between BBU and RRU is stopped in a no signal section, whereby a band required for digital RoF transmission between the BBU and the RRU is reduced.

Abstract: A light-receiving package for flat-plate mounting which can make monitor reception sensitivity of an optical signal constant without increasing the size of a module.

Abstract: The present invention relates to a light ray shift element which provides controlled refraction of the incident ray and an optical axis displacement device using the above light ray shift element. An application of these optical devices to an interleave projection display system is demonstrated. The optical element is constructed from transparent flat plate materials containing a first optical medium and are disposed at a predetermined spacing along the optical axis. The orientation angle of the transparent flat plates with respect to the optical axis can be varied independently. A bulkhead consisting of the transparent flat plates and a second optical medium having an index of refraction different from the first optical medium, which is enclosed in a hermetic extendable seal, is utilized to provide light ray shift and optical axis displacement.