Abstract: An input clock signal associated with an input data signal is divided by a predetermined integer N, to form a sub-rate clock signal. The sub-rate clock signal is sampled and transmitted along with the input data over an asynchronous data channel. At the receiver, the resulting sub-rate clock signal is received and coupled to a phase lock loop which generates a recovered clock signal of the same frequency and substantially in phase with the input clock signal.

Abstract: A signal despreader for use in a CDMA system processes samples of the received signal with filtered replicas of the code coefficient sequences associated with the system users. The symbols transmitted by each system user are recovered using a filtered replica of that user's associated code coefficient sequence. In the disclosed embodiment, the communications channel between each system user's transmitter and the base station is bandlimited. Accordingly, within each user's transmitter, filtering apparatus having a frequency characteristic is utilized to limit the frequency spectrum of each coded signal to a predetermined bandwidth equal to or less than that of the communications channel. Each filtered replica, pursuant to the present invention, reflects this frequency characteristic. In addition, the communications channel also has a frequency characteristic, and each filtered replica can reflect this characteristic as well.

Abstract: The onset of haze on silicon wafers is controlled by treating the wafers with a chemical selected from the group consisting of hot water and isopropyl alcohol and then storing the treated wafers in an inert atmosphere such as nitrogen or argon.

Abstract: An optical fiber splicing device includes a clip (20) which aligns and secures cylindrical rods (28, 30 and 32) utilized within a three-rod optical fiber splicing device. The clip (20) is a generally cylindrically shaped component which is made of a resilient material and is positionable so as to encase three cylindrical rods (28, 30 and 32). The clip (20) comprises a circular body portion (22) and two protruding leg portions (24 and 26) which extend from an point on the outer periphery of clip body (22). The two leg portions (24 and 26) are constructed and oriented such that they may be manipulated to controllably expand the inner diameter of clip body (22). To facilitate an optical fiber splice or connection, the clip (20) of the present invention allows the clip body (22) to be expanded to loosen the grip on rods (28, 30 and 32) held therein, thereby allowing the optical fiber ends to be inserted between the rods.

Abstract: Arrays of light beams are combined in a manner that minimizes optical power loss by passing a first array of light beams through an angle-variant device onto a target surface while reflecting a second array of light beams off the angle-variant device onto the target surface. The light beams of the first array are arranged to strike the angle-variant device at a first family of angles at which the angle-variant device is substantially transmissive. The light beams of the second array are arranged to strike the angle-variant device at a second family of angles at which the angle-variant device is substantially reflective.

Abstract: An objective lens for a free-space photonic switching system is disclosed. The objective lens is utilized to change a collimated array of beams into an array of spots which will focus on the array of spatial light modulating elements (S-SEEDs, for example). The requirements for the lens (low f-number, field of view, etc.), result in a lens which includes an external stop, positive doublet, a positive (e.g., plano-convex) lens and a negative (e.g., field flattener) lens, the latter pair of lenses being separated by a predetermined distance d.

Abstract: Secure teleconferencing between three or more parties is achieved by receiving encrypted information streams from each of the parties to the conference. The encrypted information streams are received in decryption/re-encryption units co-located with a conference bridge established in a telecommunication switching system in a public switched telephone network central office. The decryption/re-encryption units decrypt the information streams and then re-encrypt those information streams in accordance with a common conference encryption algorithm. The re-encryption processes for the information streams are synchronized so that the re-encryption circuitry for all information streams are in the same cryprostate at all times during the re-encryption procedure. The decryption/re-encryption units are located in secure surroundings to protect the unencrypted information streams present in those units.

Abstract: A prepaid telephone system having multilingual capabilities is provided in a public switched telephone network. A telephone user buys a predetermined amount of service beforehand and receives a card imprinted with a unique account number. A plurality of toll free access telephone numbers allows the user to access the prepaid telephone system. Each of those telephone numbers causes the prepaid system to interact with the user in the language in which he or she wishes the system to operate. The user is prompted in the chosen language to enter his or her card number. The authenticity of the number and the available credit is determined. If there is a certain minimum amount of credit available, the user is prompted to enter the phone number of a desired party. The user may also dial a speed dialing alias which connects the user to special services including news, weather, travel, translation, and other services.

Abstract: A unified and automated system for providing, restoring and optimizing special services is continually aware of the state of all the equipment and facilities in the network. The unified system responds automatically to a request for a special service by 1) designing a circuit required to support the requested special service, 2) identifying network facilities and configurations for implementing the designed circuit, 3) assigning those facilities to the circuit, 4) causing the various equipment providing the facilities to be interconnected to implement the service, 5) verifying the integrity of the special service, and 6) delivering the service to the customer.

Abstract: A transmitter suitable for ISDN use feeds the 2B1Q transmit signals directly into a sigma-delta modulator. The input word is two or three bits and the datapath within the sigma-delta modulator need be only six bits wide. The sigma-delta modulator has sample-hold means which has some filtering effect. The additional filtering requirements are met with an analog filter. No digital interpolation filter is required.

Abstract: In this invention, an optical beam is multiplexed with two independently generated electrical pulse signals applied simultaneously to an interferometer having at least two branches to perform electrical-to-optical operations, such as logic, encryption or multiplexing operations. A Y junction interferometer which is coupled to receive a CW or periodic occurring optical beam has at least one set of individually addressable contacts. A first pair of individually addressable contacts is coupled to receive a first independently generated electrical pulse signal of a given frequency and amplitude, and a second pair of individually addressable contacts coupled to the same or another branch of the Y is coupled to receive a second independently generated electrical pulse signal of a given frequency and amplitude which is other than substantially identical to and other than substantially in-phase inverse with the first signal.

Abstract: An "intelligent" maintenance termination unit (MTU) that can be installed at or near the demarcation point between the telecommunications network and Customer Premises Equipment (CPE), includes a program controlled processor arranged to perform numerous testing and evaluation functions on (1) the CPE and the drop portion of the telecommunications circuit located on the customer side of the MTU, as well as (2) the line portion of the telecommunications circuit on the network side of the MTU. Testing may be initiated in response to actuation of a pushbutton switch or other initiation means by the customer. Specific tests are then performed in response to receipt of signal sequences (such as Touch-Tone signals) received from a technician at a remote test center.

Abstract: An integrated circuit, illustratively an SRAM, with pull down gates symmetrically positioned with respect to the ground line is disclosed. The symmetric positioning helps to insure cell stability.

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: The versatility of a voice directed communications system is enhanced by centralizing voice verification and recognition apparatus and employing a frame relay network to connect such apparatus to individual ones of a plurality of platforms, each operative for establishing telephone calls in response to receipt of verbal directions from respective callers. In addition, each such platform is associated with a communications network node, such as an operator service position system, so that a caller need only dial a few telephone digits, e.g., the digits zero and zero, to access a respective one of the platforms.

Abstract: Timing recovery circuitry for recovering digital data generates a timing signal which is a function of the delay provided by an equalizer to one or more predetermined frequency components of its input signal. Advantageously, this approach is applicable to systems which utilize one or more baseband or passband equalizers. The disclosed embodiments of the present invention pertain to a dual-duplex system. In such a system, the digital data to be transmitted is divided into two different digital signals and each signal is coupled through an associated transmission channel. At the receiver, the received version of each transmitted signal is processed by an associated equalizer and the outputs therefrom are combined to recover the digital data. In the disclosed embodiments of the present invention, the necessary timing signal for such recovery is a function of the delay introduced by each equalizer to at least one predetermined frequency component of that equalizer's input signal.

Abstract: A cordless telephone arranged for operation in a frequency hopping system conserves battery power in a handset unit when this unit is located remote from an associated base unit and in a standby state. While in this standby state, the handset unit resides in a low power monitoring mode and monitors a channel pseudo-randomly selected from a plurality of available channels in the frequency hopping band for receipt of an initialization signal from the associated base unit. The base unit similarly monitors this selected one of the channels for receipt of this initialization signal from the handset unit. Should ongoing communications between the base unit and the handset unit be inadvertently interrupted, the cordless telephone quickly re-establishes communications in the frequency hopping system through an initialization process executed by both the handset unit and the base unit.

Abstract: A plug-in circuit card assembly for mounting high power electrical and optical components. The apparatus comprises a printed wiring circuit mounting high power electrical and optical components and connectors with conducting paths interconnecting the components and ones of the components with the connectors. The assembly has a structure attached to the printed wiring circuit with a heat sink formed at one end and having a pair of plates extending outward therefrom. One plate mounts a plurality of high thermal conducting pedestals each engaging corresponding ones of the components. Vent tubes are positioned between the plates with each vent tube having one end engaging one of the pedestals and an opposite end engaging the heat sink and functions to conduct heat from the components to the heat sink for dissipation.

Abstract: A half bridge power converter utilizes two oppositely phased power switches operated with unequal duty cycles. A magnetic arrangement with two inductance values having a ratio equal to the ratio of the unequal duty cycles is included in the converter to compensate for the unequal duty cycles.

Abstract: A time-division multiplex switch (100) switches a hierarchy of data rates. It sets up higher-rate connections not as a plurality of individual lowest-rate connections but as one or more time slots in each one of a plurality of sequential frames (40, 50) that correspond to that higher rate in each superframe (30). A time-slot-interchange switching element (131, 141 ) of the switch utilizes a plurality of physically or logically distinct double-buffered data memories (301, 302, 303) each corresponding to a different one of the superframe and different-size ones of the frames. Reading and writing of each of the data memories' buffers alternates with the corresponding one of the superframe and different-size frames; reading of a data memory's buffer immediately follows writing of that buffer.