679 results about "Fiber optic transmission" patented technology

There is disclosed a radio communication system in which a constitution of a base station and further a control station can be simplified. A radio communication system according to the present invention converts a received signal received by a plurality of antenna elements in a base station to a signal of different frequency band, and then conflates the converted signal in order to generate sub-carrier wave multiplex signal. The signal is converted to an optical signal, and then the optical signal is transmitted to a control station via an optical fiber. Or the control station performs weighting to phase of the transmitted signal transmitted from a plurality of antennas of a base station, and then performs frequency conversion to different frequency band, and then conflates the converted signal in order to generate the sub-carrier wave multiplex signal. The signal is converted to an optical signal, and then an optical signal is transmitted to the base station side via the optical fiber. The control station and the base station divides the received sub-carrier wave multiplex signal by each frequency band, and then the frequency of the divided signals are converted to the same frequency band in order to generate the transmitted / received signal of each antenna element. By such a constitution, it is possible to reduce constituent of the optical transmission components to the minimum and to simplify the constitution of the base station. Furthermore, it is possible to maintain the relative phase difference and the relative intensity of the transmitted / received signal of each antenna element. Because of this, it is possible to estimate an arrival direction of the received signal and to control radiation beam pattern of the transmitted signal.

A hybrid cable comprising an optical fiber, an intermediate layer surrounding the optical fiber, and an electrically insulating jacket surrounding the intermediate layer. The intermediate layers include a collection of metallic strands. The hybrid cable may be used to establish simultaneous electrical and fiber-optic connection between two communication devices. Thus, the two communication devices may simultaneously transfer optical signals through the optical fiber and perform any of various electrical functions (power transfer, eye safety control) through the metallic strands. For example, an optical transceiver may couple to an optical antenna unit through the hybrid cable. Such an optical transceiver may serve as part of a point-to-point link, a point-to-multipoint link, and / or, a link between a primary transceiver unit and an optical router.

This invention generally relates to an optical filter for a fiber optic communication system. An optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source.

An optical signal return path system includes a transmitter having a sample clock generator for generating a sample clock and an RF signal receiver for receiving and converting an analog RF data signal into a first data stream of digitized RF data samples at a rate determined by the sample clock. Supplemental channel circuitry provides a second data stream. A multiplexor receives and combines the first data stream and second data stream, and an optical transmitter converting the combined data stream into a serialized optical data signal for transmission over an optical fiber. The second data stream may contain maintenance data reflecting an operational state of the transmitter. A receiver receives the optical data signal and recovers therefrom a digital data stream and an associated first clock having an associated first clock rate. The data stream is stored in a memory device at the first clock rate. A clock generator generates a second clock having an associated second clock rate that is adjusted in accordance with a clock control signal. A control circuit reads data from the memory device at a rate corresponding to the second clock rate and generates a fullness signal that indicates whether the memory device is more full than a predefined threshold fullness level. A clock speed adjusting circuit generates the clock control signal in accordance with the fullness signal.

An improved fiber-optic communications system comprises a multi-mode waveguide carrying an optical signal, a single-mode waveguide optically coupled to and receiving the optical signal from the multi-mode waveguide and an adiabatic coupler optically coupled between the multi-mode waveguide and the single-mode waveguide. The multi-mode and single-mode waveguides may be optical fibers. The adiabatic coupler may comprise a tapered core surrounded by a cladding. Alternatively, the adiabatic coupler may comprise a core surrounded by a cladding, wherein the refractive index of at least one of the core and the cladding varies over the length of the adiabatic coupler.