Abstract: A phase-lock loop (FIG. 1) is initialized at power-up by an oscillator (14) control signal (28) that has previously been stored by a processor (20) in a non-volatile memory (27). The stored control signal is generated by the phase-lock loop's controller (12) in response to receipt of a calibrated reference input signal, as part of manufacturing of the phase-lock loop and occasionally thereafter during normal operation. Being stored in non-volatile memory, the control signal is not lost upon removal of power from the phase-lock loop. The stored control signal is then used to control the oscillator instead of the controller's output upon power-up and until the later one of (a) receipt by the phase-lock loop of a valid reference signal and (b) receipt of a directive for the controller to take over control of the oscillator.

Abstract: Transmission of clock signals at the pump wavelength of an optical amplifier utilized to amplify data signals being communicated in an optical network. The clock signals synchronize the data signals to a terminal utilizing the optical network. The pump wavelength is generated by a pump laser which supplies the amplification power for the optical amplifier. The clock signals are communicated on the pump optical wavelength by directly modulating the pump laser or by using an external modulator which inhibits the transmission of the pump laser's output.

Abstract: A system combining LAN and telecommunication capabilities to provide a high speed wireless LAN capability and to simultaneously provide wireless ISDN capability within an office. The LAN and ISDN information is communicated over a common transmission medium. The system also allow a user to interconnect wireless ISDN digital terminals to any other ISDN equipment anywhere in a PBX switch system or the public network. The system provides for communication of information between wireless LAN units and ISDN equipment. For example, this function allows a local computer using a local LAN interface to communicate with a remote computer via ISDN switching facilities. Further, the expense of hiding unsightly wiring in an office environment can be avoided, and the cost of moves and rearrangements of equipment can be greatly minimized.

Abstract: A communications signal-transmitting device carried by a communications system user indicates the location of that user relative to other wired or wireless communications devices connected to a communications system. This location indication is utilized by the communications system to forward incoming voice and/or data communications for that user to the other communications device so that the user can receive such communications. As a result, the location of any potential system user is provided and call forwarding for that user is accomplished without the prior art problems associated with activation and deactivation. In the disclosed embodiments which pertain to the forwarding of voice communications in a PBX environment, the communications device is a pager which communicates with the wired or wireless telephone sets connected to the line side of the PBX to provide the PBX with the location of the system user relative to these telephone sets.

Abstract: Optical fiber (12)extending from an optical coupler (11) is routed on a substrate layer (13) by first inserting the optical coupler in a device holder (16) having a slotted member (17). An opening in a substrate layer is made to match a cavity (19) in a support member (20). The device holder is inserted in the cavity (19) of the support member (20) and the substrate layer (13) is supported by the support member (20) such that the opening exposes the device holder (16). The optical fiber extending from the optical coupler is inserted into a slot of the slotted member (17) such that a bridging portion (21) of the fiber bridges a distance between the upper surface of the substrate layer (13) and the slotted member (17). The bridging portion of the optical fiber is engaged with a routing device, and the fiber is then muted on the upper surface of the substrate layer (13).

Abstract: Solving the aging problem of crystal oscillators by doing field recalibration. The solution is to utilize an accurate external reference signal to determine when the frequency of the digital temperature compensated crystal oscillator (DTCXO) has drifted from the reference signal in excess of a specification. When this occurs, the DTCXO has used its internal compensation values to correct its output hence the difference between the external reference signal and the frequency of the DTCXO in excess of the specification is due to aging. A new compensation value for the present temperature is calculated using the reference signal. Using the well known fact that the temperature aging uniformly shifts the frequency over the temperature range, a controller utilizes the difference between the new compensation value and the stored compensation value for the present temperature to shift the entire set of compensation values to compensate for the aging effect.

Abstract: A cellular telecommunication switching system responsive to an emergency call from a cellular telephone to request that the geo-coordinates be transmitted from the cellular telephone and to convert those coordinates into conventional municipality or rural address location information. In one embodiment, the cellular telecommunication switching system utilizes an internal database to convert the geo-coordinates to location information. In another embodiment, the cellular telecommunication switching system utilizes an external database to perform this conversion. In yet a third embodiment, a cellular telephone performs the conversion and transmits to the cellular telecommunication switching system the location information.

Abstract: Detecting and evaluating optical subcircuits created by optical splitters in an optical circuit. One or more optical wavelengths are utilized for the transmission of data; whereas, other optical wavelengths are utilized to perform optical time domain reflectometry measurements on each optical subcircuit. Following an optical splitter, each optical path from the optical splitter has inserted into it an optical filter which allows the transmission of the optical wavelengths utilized for data transmission and one of the optical wavelengths utilized to perform the optical time domain reflectometry measurements. An optical time domain reflectometry instrument transmits each of the optical wavelengths, utilized for testing, individually into the optical circuit and analyzes the returned optical pulse. Since only one optical subcircuit allows the passage of any given optical wavelength for testing, each optical subcircuit can be fully analyzed.

Abstract: Replacing costly electro-optic or fused quartz crystalline structures or molded plastic optical waveguide splitters with an optical switch comprising an array of spatial light modulators between two relatively, thick, optical glass flats. Associated with each spatial light modulator are partial holes in the optical glass flats with the partial holes being in alignment with the spatial light modulator. Using a new experimentally-developed laser technique, these holes can be drilled to a precise depth so that the distance between the ends of standard silica optical fibers inserted into opposing holes approximates the diameter of those fibers. Since the diameter of a partial hole is insignificant compared to the overall area of an optical glass flat, the physical strength of the optical glass flats is not reduced even when a number of partial holes are drilled into the optical glass flats.

Abstract: An apparatus to determine characteristics of an optical communication path by utilizing electrical devices in an electrical path in parallel with the optical communication path. Each electrical device is physically located with a passive or active optical device and specifies the attenuation and delay of the optical device. A receiver measures the electrical qualities of each electrical device in the electrical path which is parallel to the optical path from the optical transmitter. The electrical measurements allow the receiver to automatically adjust its optical receiver to the attenuation and delay introduced by the optical devices in the optical path.

Abstract: An optical coupler using round optical fibers whose ends have been formed into a predefined shape to allow greater physical packing densities in order to achieve greater uniform illumination efficiency. The interstitial space between optical fibers is greatly reduced by thermoforming the ends of round optical fibers in a mold that makes a gradual transition from a circular shape to the predefined shape to avoid optical loss. Since the change in shape is gradual, the total cross-sectional area of the fibers remains constant; and optical loss is minimal because there is no reduction in mode volume. The predefined shape may be substantially square or rectangular. The core and cladding materials of the optical fiber are carefully chosen with respect to the glass transition state temperatures of both materials because the temperature at which the materials are formed by a mold are slightly above the glass transition state of the core or cladding, whichever is higher.

Abstract: A communications switching system such as a PBX, central office switch and the like, responds to an incoming call to a called party by signaling a paging device as well as some other communications device having communications capability different from that of the paging device. In the disclosed embodiment, which pertains to a private branch exchange (PBX), this other communications device is one which provides two-way voice communications. Advantageously, the paging device may also be provided with the capability of signalling the communications system that the called party will shortly answer the call via a communications device possessing two-way voice communications. Upon receipt of this pager-transmitted signal, the communications system, if desired, can be provided with the ability to provide an announcement to the calling party of the called party's intent to answer the call.

Abstract: Molding optical components from a mold that is produced using the same type of optical fibers that will be interconnected by the optical components. The outer diameter of a silica optical fiber varies only by approximately .+-.1 micron and the outer surface of a silica optical fiber has an optical finish. Thus by using optical fiber to fabricate molds, molds can be produced which have the required accuracy and finish for the production of optical components. The outer coating of the optical fibers used to fabricate the mold is only removed within and in close proximity to a combination region in a splitter/combiner resulting in the capability to pigtail optical fibers attached to a splitter/combiner molded from the resulting mold.

Abstract: Molding optical components from a mold that is produced using the same type of optical fibers that will be interconnected by the optical components. The outer diameter of a silica optical fiber varies only by approximately .+-.1 micron and the outer surface of a silica optical fiber has an optical finish. Thus by using optical fiber to fabricate molds, molds can be produced which have the required accuracy and finish for the production of optical components. The outer coating of the optical fibers used to fabricate the mold is only removed within and in close proximity to a combination region in a splitter/combiner resulting in the capability to pigtail optical fibers attached to a splitter/combiner molded from the resulting mold.

Abstract: Utilization of an electrical link separate from an optical transmission path to gather information identifying the number and types of optical devices in the optical path and utilization of this information to adjust the power output level of an optical transmitter and to transmit the power output level to optical receivers connected to the optical transmitter by the optical path. Each optical receiver is responsive to the number and types of optical components in the path between the optical receiver and the optical transmitter and the power output level to adjust the sensitivity of the optical receiver. Each optical component is associated with an electrical identification circuit connected to the electrical link which specifies the information on the electrical link concerning the optical component including the performance characteristics of the optical component.

Abstract: Visual indication of an operational condition on a printed circuit board by utilizing a pair of LEDs for each operational indication and by utilizing each LED of a pair to verify that the other LED can emit light greater than a predefined level. In addition, if an error condition is determined to exist in a pair of LEDs, a central processor is notified of this fact to allow the error condition to be remedied. Further, if a failure is detected in the pair, both LEDs are utilized to indicate an operational condition on the printed circuit board. This increases the probability that the LED pair will be able to indicate the operational condition.

Abstract: Depolarization of light by utilizing a small concentration of refractive or diffractive microparticles in an optical core of an optical coupler that is coupling light from polarized source to a polarization type optical switch such as a ferroelectric liquid crystal. The result is that light from the laser is bent slightly by either the refractive or diffractive effects of the microspheres which causes scattering; and as a consequence, the light is depolarized in a relatively short distance within the optical core before reaching the liquid crystal switch. The microparticles maybe closely matched to the index of refraction of the core material resulting in smaller deflection angles and lower reflections. In addition, these microparticles match the specific gravity of the core material such that they do not settle out of suspension while the core material is being hardened from a semi-liquid state.

Abstract: An apparatus for duplicated clock circuits using equivalent devices in monolithically package devices and cross-coupling local clock signals of each clock circuit over the appropriate link cables with the other clock circuit. The apparatus distributes the local clock signal to both clock circuits for precise delay compensation. Further, the apparatus utilizes the propagation delay matching of semiconductor devices in the same package on the same monolithic substrate and the matching of interconnection impedances in corresponding devices in different packages to closely match the phase of duplicated clock signals. It further takes advantage of the fact that the locally used clock signals not normally cross-coupled are cross-coupled using cables which are chosen in length to exactly compensate for the actual cross-coupling delays in the cables; and since the routes are chosen to be the same, the temperature variations which cause small differences in propagation speeds through the cables are also compensated.

Abstract: A duplicated transmission system in which two optical wavelengths are utilized on each of a pair of optical links with one optical wavelength communicating data and the other optical wavelength communicating a signal designating an active optical link of the pair. Each of the optical links is terminated on a transmit unit and a receive unit. The two transmit units determine which of the optical links is the active optical link, and each of the transmit units then transmits a signal on the second wavelength of the terminated optical link indicating this decision. The second wavelength of the active optical link designates that it is active, and the second wavelength of the standby optical link designates that it is the standby optical link. Upon reception of the information on the second wavelengths, the receive units both select the active optical link.

Abstract: An optical switching unit requiring no optical-to-electrical conversions on optical data paths being switched through the optical switching unit. The optical switching unit receives optical data information from one terminal and switches it to another terminal. The optical switching unit frame synchronizes the data transmission timing of the terminals in accordance with the data transmission timing of the optical switching unit. This frame synchronization eliminates the need to provide data buffering and frame synchronization in the optical switching unit. The optical switching unit comprises an optical network, system clock, optical input interfaces for receiving information from terminals, and optical output interfaces for transmitting information to terminals. The system clock determines the timing of each terminal using information transmitted to an optical input interface by the terminal.