Abstract: An optical duplex system may continue to operate after a break in a fibre if light is reflected at the break and received back at the transmitting station, and that station is unable to identify the origin of the data. To prevent this, in a simple 2-channel duplex system, data transmitted from one end is inverted prior to transmission and reinverted at the receiving end, while information from the other end is transmitted and received without inversion. If there is a break, the stations at both ends will receive inverted data and the fault is quickly revealed. In a 2.times.4 channel multiplex system, one channel from one end is inverted before transmission, while three channels from the opposite end are inverted before transmission.

Abstract: A fiber optic communication system especially adapted for use with a programmable industrial controller includes a machanism for evaluating the quality of the fiber optic link. The system includes a transmitter for sending a different unique character over the fiber optic cable at a plurality of light intensities. A receiver is coupled to the fiber optic cable for receiving the characters from the transmitter. The receiver determines whether information was received at each of the plurality of light intensities by determining which of the unique characters were received. In response to the determination of the light intensities that were received an evaluation of the quality of the fiber optic communication system is made.

Abstract: An optical atomic resonance filter using two pump lasers, a buffer gas and magnesium as an atomic vapor converts underwater signals in the Fraunhofer wavelengths in the green portion of the spectrum to UV light which is readily detectable by conventional photomultiplier tubes.

Abstract: A switching apparatus and adjustable time delay protocol to provide switching between N processor system devices in which each device is connected via N+S fibers to N+S switching planes, with one fiber being used for the connection from a device to one of the N+S switching planes. N fibers provide the desired bandwidth and S fibers are used as standby fibers in the event of failure of any of the N fibers. An additional C fiber from each device to a single matrix controller are used to provide control information. The single controller provides control for all N+S switching planes. Each switching plane converts the optical signals that are received over M fibers to electrical signals. The electrical signals are then switched and converted to optical signals by the respective switching planes. Thus, each of the optical signals received over each of the M fibers are transmitted to a respective other one of the M fibers.

Abstract: A transmitter and receiver for "MILES" type systems is in a pistol type configuration, and is provided with a display, to indicate the mode of the controller unit, as well as the specific MILES codes which are transmitted or received. The versatile unit is particularly flexible in its ability to test the various components of Multiple Integrated Laser Engagement System, with "MILES" being the acronym for these combat training exercise systems. A continuous rotary control switch determines the mode, either (1) transmit, (2) receive, or (3) identity change. In the transmit mode, rotation of the switch will change the transmitted MILES code, and actuation of the trigger switch will transmit the MILES code and an associated identity code. In the identity change mode, operating the trigger switch will change the I.D. number of the "player". In the receive mode, the display will show the received MILES code, and the player identity number.

Abstract: A beam deflection system for use in optical radar, communications, or optical display apparatus, having the ability to scan multiple "target" clusters that are widely scattered over a large angular field. In its transmission mode of operation, the system switches a laser beam sequentially across an array of focal elements, moving the beam at high speed, since total beam movement across the array is limited to only a few degrees. The system includes an expansion telescope, which expands the succession of beams from the array of focal elements and directs them onto an array of larger, movable optical elements, such as gimbaled mirrors, which direct the successive beams toward scattered target areas in a large angular field. The system also includes a beam scanning device, for "microscanning" the beam through a number of separately resolvable positions within the field of view of each of the array of focal elements.

Abstract: An electronic appliance, which can facilitate operation of a commander for transmitting a remote control signal for the electronic appliance, includes a receiver for receiving a remote control signal from a commander, a plurality of input terminals for receiving video signals from external signal sources, a signal selection switch for selecting one of the signals received at the input terminals and a broadcast signal and for delivering the selected signal as an output video signal therefrom, a code converter operable in response to the condition of the signal selection switch for converting a signal received at the receiver into a code by which the pertaining signal source can be controlled, and an output terminal for supplying an output of the code converter therefrom to the pertaining signal source via a signal cable.

Abstract: The invention is for an optical communication apparatus for bidirectionally transmitting and receiving supervisory and audio signals. The apparatus includes a telephone line interface unit that receives electric audio and supervisory signals and converts them to optical signals. It is also includes means for receiving optical signals representing audio and supervisory signals. A data unit receives the optical audio and supervisory signals from the interface unit and converts them to electric audio and supervisory signals, and also includes means for receiving electric audio signals and supervisory signals and converting them to corresponding optical signals. An optical link connects the telephone line interface unit and data unit for bidirectional optical communication. A method of practicing the invention is also included.

Abstract: In an infrared communication system in which many units of different requirements can communicate with each other, transceivers are assigned to different categories, each with its own transmitting power and receiving sensitivity depending on the required distance range. This allows simultaneous independent infrared communications in different local areas between low power/sensitivity devices but enables also transmission over larger distances or over the whole system between larger power/sensitivity devices. Depending on the power/sensitivity relation and distance, a potential receiver may either be able to decode data signals correctly, or it may be only able to detect the presence of a carrier. To allow a clear access protocol in all cases, a unit gets two chances to reenter access competition after having sensed the carrier: Either upon decoding a data end delimiter, or upon a timeout equal to the longest possible packet transmission time.

Abstract: A method and system for demultiplexing an optical signal having a bit rate in the order of GBit/second. The system comprising optical demultiplexing means including delay units and sampling devices such as optical modulators which are controlled at the Bit Rate so that the output signals of the optical modulators correspond to respective ones of the four channels of the original multiplexed signal. These demultiplexed signals may then be converted by regenerators into corresponding electrical signals.

Abstract: An optical wavelength-division switching system comprises means for reproducing an electric signal for each channel from a wavelength division multiplexed optical signal, and means for converting the electric signal to a modulated optical signal. The means for reproducing the electric signal can be composed of an optical heterodyne or homodyne detection system, while the means for converting the electric signal can be composed of a distributed feedback laser diode having an optical frequency modulating characteristic so that the number of channels is much increased with the decrease of crosstalk.

Abstract: The node includes plural optical receivers and transmitters. Each receiver and each transmitter of the node is connected to a user terminal by fiber optic cables. The output of each of the node receivers is electrically combined. Splitting logic is also included for splitting the electrical output of the receivers to serve as an input to the plural optical transmitters. The node may be used as an expansion mode or as a head-end unit. The optical receivers and transmitters have a low cost so that the overall node is approximately one fifth the cost of comparable nodes utilizing passive optical stars.

Abstract: Supplied with an optical signal from a directly modulated semiconductor laser (11) in an optical transmitter, an optical frequency discriminator (15) converts a frequency modulated component of the optical signal to an intensity modulated component and produces an output optical beam which consists essentially of the intensity modulated component. Preferably, a negative feedback circuit (32, 33) is supplied in effect with the output optical beam representative of mark and space codes and controls the semiconductor laser and/or the optical frequency discriminator to keep the extinction ratio of the output optical signal at an optimum value such that the optical frequency discriminator has a transmissivity of about 90.degree./o for a predetermined one of the mark and space codes and a substantially zero transmissivity for the other of the mark and space codes.

Abstract: The present invention relates to a technique for repelling carriers in a Frequency Division Multiplexed (FDM) lightwave communication system to minimize mutual interference between signals. The system comprises a plurality of transceivers (20), each comprising a transmitter section (30) and a receiver section (40) which is coupled to a separate user of the system on one side, and on the other side to a lightwave communication arrangement (21-23) that interconnects the plurality of transceivers. Each of the transmitter sections of the system uses a separate carrier (10-14) for transmitting an associated users' information signal, and, during each sequential test cycle period, slowly dithers this carrier in random order to a first nearby frequency (50), on one side of the nominal carrier frequency, and then to a second nearby frequency (51) on the other side of the nominal carrier frequency.

Abstract: A two-wire full duplex frequency division multiplex (FDM) modem system having a unit for cancelling a transmission signal, taking into consideration the line distortion characteristics. The FDM modem system includes two modem units connected through the two-wire full duplex transmission line.Each modem unit includes a unit for modulating a transmission data, a unit for synthesizing the modulated transmission signal and a reception signal, a unit for adding the signal from the synthesizing unit and a signal, a unit for demodulating the reception signal, and a unit for generating the signal supplied to the adding unit cancelling a transmission echo signal included in the signal from the synthesizing unit, from the signal modulated at the modulating unit and the signal from the adding unit. The adding unit subtracts the signal generated at the echo cancellation signal generation unit from the signal from the synthesizer unit.

Abstract: The present invention relates to packet switched interconnection protocols for use in high-speed optical Star-configured Local Area Networks (LANs). In the present Star LAN, a plurality of N+1 wavelength division multiplexed (WDM) channels are provided for use by M transceivers connected to the Star coupler, where preferably M>N. N of the N+1 WDM channels are used for transmission of data packets, and the remaining WDM channel is used by all transceivers for transmitting control packets only. In the present protocols, a transmitter in an active transceiver first send a control packet over the control channel using a first protocol such as, for example, ALOHA or CSMA. The control packet includes (1) the transmitter's unique address, (2) the destined receiver's address, and (3) the address of the data channel to be used in transmitting the associated data packet.

Abstract: An information medium comprising a receiving section, a transmitting section, and a transfer-control section. The receiving section receives instructions from an external device. The transmitting section transmits data to the external device. The transfer-control means detects the ID code contained in any instruction information supplied to the receiving section, and changes the transfer program stored in memory when the ID code specifies a program-change instruction. The changed program is supplied to the external device via the transmitting section, so as to be recognized by the external device. Any instruction information supplied to the information medium has an enabling code field, an identification code field, a data field, and an end code field. The transfer-control section includes a control section and a memory unit.

Abstract: A receiver for optical digital signals has a transimpedance amplifier, the input of which is connected to an operating voltage via an active photodiode, and the output of which is connected to an input of a comparator. An operational amplifier is provided, the one input of which is connected to the input of the transimpedance amplifier, and the other input of which is connected to the operating voltage via a further, unilluminated photodiode. A reference voltage at the other input of the comparator is generated from the output voltage of the operational amplifier via a voltage divider.

Abstract: A self guided vehicle has a roller deck controllably powered by an electric motor to accept and deliver loads on both the left and right side of the vehicle. An infrared communication system is employed to coordinate the overall transfer of these loads between the vehicle and a docking station. The communication system performs the multiple functions of locating the docking station relative to the left and right side of the vehicle, determining the direction the load is to be transferred, and controlling the direction of motor rotation to effect such a transfer.

Abstract: A receiver for optical digital signals which have different amplitudes which comprises a transimpedance amplifier which has a photodiode connected to its input and which produces an output that is supplied to one of the inputs of a comparator. Oppositely poled diodes are connected between the inputs of the comparator and a reference voltage is supplied to the other input of the comparator and a capacitor is connected to the other input of the comparator which together with a resistor comprises a differentiator for the output signals of the transimpedance amplifier.