Abstract: A wireless intrasatellite communication system is disclosed. Satellite telemetry signals are multiplexed, converted into a digital data stream, and processed by an ASIC to form a multiplexed telemetry data stream. An infrared transceiver transmits the multiplexed telemetry data stream along an optical path to a designated interface that is associated with a remote command and telemetry unit. Telemetry signals are aggregated within a plurality of remote command and telemetry units and transmitted to a central command and telemetry unit via a high-speed digital bus. Command data issued from the central command and telemetry unit is distributed to a designated remote command and telemetry unit, and is routed to the appropriate user unit via the optical path. The user unit processes the command data and generates a responsive command signal output.

Abstract: An apparatus for looping-back an optical signal in an optical communications system includes a transmitting station and a receiving station optically coupled to the transmitting station by a transmission fiber and reception fiber. Data is transmitted from the transmitting station to the receiving station through the transmission fiber and is also transmitted from the receiving station to the transmitting station through the reception fiber. The apparatus includes a beam splitter having an input port, an output port and a tap port, operationally coupled to the transmission line. The beam splitter is capable of diverting a preselected beam portion of an optical data beam being transmitted through the transmission fiber to the tap port. A tap fiber that is operationally coupled to the tap port allows the preselected beam portion to propagate therethrough. An optical analyzer, optically coupled to the tap fiber, regenerates the preselected portion, thereby creating a return beam.

Abstract: A method to determine a switching moment (Ti) of a switch (SWi) is provided. The switch is coupled to an optical combiner (OC) of a tree-like optical network. The optical combiner enables multiple access of information signals (IN1, . . . , INi, . . . INn) which are upstream transmitted from network units (NU1, NU1′, NU1″, . . . , NUi, . . . , NUn) to a line terminator (LT) via the cascade connection of dedicated branches (B1, . . . , Bi, . . . , Bn), the optical combiner and a common branch (BC). The switch passes an information signal (INi) at an approximated switching moment (APP-Ti) when the information signal is present and interrupts the branch when the information signal is not present.

Abstract: A system and method for reducing Raman cross-talk between optical signals having different wavelengths in an optical communications system. Optical signals having wavelengths &lgr;1, &lgr;2, &lgr;3, and &lgr;4, respectively, are launched into an optical fiber at the headend of the system by an optical transmitter. Each wavelength &lgr; is preferably separated from each adjacent wavelength by the same amount, &Dgr;&lgr;. &lgr;1 and &lgr;2 have vertical polarizations and &lgr;3 and &lgr;4 have horizontal polarizations. Because there is no Raman cross-talk between orthogonally polarized optical signals, there will be no Raman cross-talk between &lgr;1 and &lgr;3, between &lgr;2 and &lgr;4, between &lgr;1 and &lgr;4, or between &lgr;2 and &lgr;3. However, there is Raman cross-talk between &lgr;1 and &lgr;2 because each is vertically polarized and also between &lgr;3 and &lgr;4 because each is horizontally polarized.

Abstract: A monitoring method for optical communication equipment wherein the levels of the total signals on a plurality of optical fibers are checked, the signal qualities of the individual communication channels which are respectively transmitted on one fiber are cyclically monitored, and all criteria are evaluated in order to establish a monitoring algorithm by which the critical channels are monitored more intensively than reliable ones.

Abstract: The invention concerns a system for compensating polarization dispersion of channels in a wavelength-division multiplex signal. In accordance with the invention, the system comprises a plurality of cascaded polarization control modules respectively associated with said channels and a common differential delay generator. Each polarization control module comprises a drop and insert multiplexer for extracting the signal from the associated channel from the input multiplex signal and inserting a modified channel supplied by a polarization controller. The system further comprises a control loop for controlling the polarization controllers in response to the optical properties of the channel signals at the output of the differential delay generator and obtaining a compensated multiplex signal.

Abstract: A wavelength division multiplexed optical system utilizes a plurality of lasers each operating at a different wavelength. Each laser is directly modulated with independent data at an NRZ signal of a given bit rate frequency and their outputs are combined as a train of pulses in a single optical fiber in the WDM format. The train of pulses is passed through a Mach-Zehender modulator driven with a sine wave synchronized with the bit rate of the NRZ drive to the lasers.

Abstract: An optical signal receiving apparatus capable of substantially instantaneously and stably discriminating the logic from the header of a burst-like optical signal comprising a pre-amplifier circuit for amplifying an output from a photodiode receiving cell signals, a dummy side variable gain amplifying unit for performing the gain control by feedback control with respect to the output from the pre-amplifier circuit and outputting the gain at that time as gain information, a memory unit for holding the gain information, and a signal side variable gain amplifying unit for performing the gain control by feedfoward control by using the gain set by the gain information and outputting the amplified signal.

Abstract: The present invention relates to an arrangement and a method for detecting faults in an optical fiber network, comprising at least two nodes arranged with at least two optical fibers to a bus with the end nodes connected via two spare fibers. Every node comprising a central module (50), at least two protection switches (60,61) and optical amplifiers (21,22,23,24) and said central module comprising at least one central processor (51), at least one logical unit (52), at least one protection signal transmitter (53) and at least one protection signal monitor (54). The end nodes of the bus transmit a protection signal in at least one direction of the bus and said end nodes can detect the own protection signal and the protection signal transmitted from the other end node. All nodes in the bus can detect Optical Power Loss, OPL. The bus will reshape into new end nodes in case of a fault.

Abstract: In a method for deciding the level of an input signal, positive and negative signals are provided in response to the input signal. A peak of the positive signal is detected to provide a positive-peak value. A peak of the negative signal is detected to provide a negative-peak value. The positive signal and the negative-peak value are combined to provide a first combination signal. The negative signal and the positive-peak value are combined to provide a second combination signal. The first and second combination signals are compared to provide an output signal of zero or one.

Abstract: In an optical transmitter, light outputs with different wavelengths are emitted from a plurality of light sources by a plurality of driving circuits, respectively. An optical switch control circuit controls an optical switch in response an input connection instruction such that an optional one of a plurality of input ports is connected to an optional one of a plurality of output ports to pass the light output from the optional input port to the optional output port. A plurality of modulator driving circuits drive a plurality of optical modulators in accordance with a plurality of data signals such that the light outputs from the output ports are optically modulated by the plurality of optical modulators, respectively.

Abstract: It is the object of the invention to provide a WDM optical transmission system, in which the transmission performance of the system is optimized by keeping an optical power per an optical signal constant, independent of the number of the optical signals. An alternating current (AC) voltage of a frequency f.sub.1 is supplied to a burst generator, and control bursts S.sub.1 to S.sub.n (frequency f.sub.1) with different transmitting times are generated by the burst generator. These control bursts are respectively supplied to laser diodes (LDs) provided with control circuits, and directly modulate the output of the LDs. Moreover, the output of the LDs are respectively modulated by external optical modulators, multiplexed by an optical coupler and emitted to an optical fiber.

Abstract: A remote infrared password key system teaches entering a password with a remote control, conveniently entering a password by pressing one key utilizing a password hot key which also eliminates the need to store the password, and preventing unwanted disclosure of the password, by using a remote infrared password key system.

Abstract: In an optical branching/multiplexing apparatus, to effect harmful influence to transferring characteristic of optical signal of wavelength penetrated through an optical branching device is prevented. At the optical branching device, a specific wavelength signal is subjected to an optical-branching, while another wavelength signal with exception of the specific wavelength is penetrated in wavelength division multiplexed main input signal. Multiplexed input signal is amplified by an optical amplifier 7 with variable gain, before amplified signal is divided by a photo coupler to be applied to the optical multiplexing device and to the other hand input sides of a comparator.

Abstract: A bi-directional protection facility is provided in an optical communication system in which an optical communications node communicates with another optical communications node via first and second bi-directional communications paths respectively serving as a service path and protection path, and in which a filter at each node processes signals respectively received over the service and protection paths and generates an in-band signal and out-of-band signal for each of the paths. A control unit then generates a Loss of Signal indication for the service path if the level of the out-of-band signal is found to be greater than the level of the in-band signal and protection switching is effectuated as a function of the presence of the control signal. In addition, an outgoing signal to the other communications node is interrupted for a sufficient period of time to cause a LOS at that node and thus trigger protection switching thereat to complete the bi-directional switching process.