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: 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: An optical transmission system, especially useful in undersea applications, includes an optical path between two terminals with one or more repeaters located between the terminals for amplifying optical communications signals flowing in the optical path. The repeaters contain optical fiber amplifiers driven by pump lasers. The average optical power produced by the pump lasers is controlled in proportion to the magnitude of electrical line current produced by a controllable constant current source located in one of the terminals. This is achieved by regulator circuits which are responsive to a signal related to the magnitude of the line current and signals related to the actual optical output of the pump lasers. The magnitude of the line current may be conveniently set at the terminals so that the lowest bit error rate is achieved in the transmission system.

Abstract: A monolithically integrated optical filter which is rapidly tunable over a wide optical frequency range comprises an input frequency router connected to an output frequency router by means of controllably transmissive waveguides. A control circuit applies electrical energy to predetermined controllably transmissive waveguides to tune the optical filter to a desired one or more of a plurality of multiplexed input optical frequencies. This filter is economical to construct and is useful in high capacity, high speed optical communications networks.

Abstract: Application programs compiled for a first, "source", computer are translated, from their object form, for execution on a second, "target", computer. The translated application programs are linked or otherwise bound with a translation of the source computer system software. The translated system software operates on the image of the source computer address space in the target computer exactly as it did in the source computer. The semantics of the source computer system software are thus preserved identically. In addition, a virtual hardware environment is provided in the target computer to manage events and to deal with differences in the address space layouts between the source and target computers.

Abstract: Dissipation of the heat produced by the operation of electronic circuitry may be improved by a heat sink which comprises a flat base from which a number of vertical fins extend. The fins are parallel to one another and define a number of parallel channels into which coolant flow is directed. The thermal resistance of the heat sink is optimized by setting fin thickness and channel width parameters to appropriate values. The heat sink may be attached in a heat conductive manner to a heat producing electronic component. One or more of these heat sinked components may be laid out in an in-line or staggered arrangement on a support in the form of a circuit pack. Cooling fluid is delivered to the circuit pack in a variety of ways to cool the heat sinked components. A method of determining the optimum fin thickness and channel width parameters involves determining a relationship between total thermal resistance of the heat sink and combinations of fin thickness and channel width parameters.

Abstract: Non-intrusive monitoring and analysis of real-time facsimile transmissions is accomplished. Analog impairment measurements are made on the high speed page signal in those transmissions and protocol analysis is made on the low speed control messages in those transmissions. These measurements and analysis are a powerful tool for trouble shooting service problems afflicting facsimile transmissions. Actual customer traffic can be monitored to detect circuit impairments and to evaluate service being provided. Customer complaints can be handled by providing them with a special phone number which may be called to provide the ability to have the facsimile transmission experiencing a problem specially directed through the facsimile analyzer and forwarded to the intended destination while it is being non-intrusively monitored by service personnel who then can quickly provide the customer with a diagnosis of the problem.

Abstract: Dissipation of the heat produced by the operation of electronic circuitry may be improved by a heat sink which comprises a flat base from which a number of vertical fins extend. The fins are parallel to one another and define a number of parallel channels into which coolant flow is directed. The thermal resistance of the heat sink is optimized by setting fin thickness and channel width parameters to appropriate values. The heat sink may be attached in a heat conductive manner to a heat producing electronic component. One or more of these heat sinked components may be laid out in an in-line or staggered arrangement on a support in the form of a circuit pack. Cooling fluid is delivered to the circuit pack in a variety of ways to cool the heat sinked components. A method of determining the optimum fin thickness and channel width parameters involves determining a relationship between total thermal resistance of the heat sink and combinations of fin thickness and channel width parameters.

Abstract: Congestion in a high speed connection oriented packet network carrying bursty data and real time service is avoided by a novel in-call negotiation scheme for reserving bandwidth for real time calls and reserving buffer capacity for bursty calls.For a real time call, a centralized call controller in each switch in the network determines which of its outgoing trunks has available to it the peak bandwidth needed to accommodate the call. Once one of these trunks is found, the call routing is set up so that the call is directed through that trunk and the peak bandwidth requirement of the call is allocated on that output trunk for the duration of the call.The network contains one or more switches, each of which has a centralized call controller and a plurality of trunk controllers. The call controller routes calls from a plurality of input trunks to a plurality of output trunks, identifies kinds of calls, and allocates bandwidth on the output trunks.

Abstract: An errorless line protection apparatus involves receipt of data from an active line and a standby line. A determination is made as to whether the data from the active line leads or lags the data on the standby line. A switching system directs the leading data to a lead channel containing a controllable amount of time delay up to the maximum amount that the leading data is expected to led the lagging data. Lagging data is directed to a lag channel. A selected one of the data from the lead channel or the lag channel is delivered to an output line.

Abstract: Apparatus is disclosed for generating two streams of optical pulse signals having less than 100 femtoseconds of jitter. A Ti:sapphire laser that is self mode locked by using self focusing in the gain medium and a weak HITCI intercavity dye jet for starting generates a first stream of substantially 100 femtosecond pulses. This first stream of optical pulses is split into two parts, one of which is used as a desired stream of optical pulses and the other of which is used to pump an HITCI dye laser synchronously to generate a second desired stream of optical pulses. The pulses of the second stream from the dye laser have durations of about 140 femtoseconds and less than 100 femtoseconds of jitter relative to the pulses of the first stream.

Abstract: A system for determining the presence or absence of data on one or more data lines including a flip-flop for each data line with the output of each flip-flop connected to a NAND gate. The NAND gate is connected through an OR gate to two output flip-flops in series. The logic of the system is such that the output of the second of the two output flip-flops provides a signal level which is high or low depending on whether data is present on all of the data lines or one or more lines has no data.

Abstract: A data scrambler circuit which adds the SONET polynomial 1+X.sup.6 +X.sup.7 to data in a parallel format to thereby reduce circuitry clock rates to one-eighth the line rate, which reduces power consumption and simplifies timing constraints. A circuit embodiment includes a first series of flip-flops connected to generate the polynomial and a second series of flip-flops for holding the generated polynomial. The parallel data is added to the held polynomial by a series of exclusive OR gates.

Abstract: A protective circuit for removing power from a load detects the presence of a control signal which causes electrical power to be delivered to a load, for example, via a controlled switching device such as an electromechanical relay or a solid state relay. The protective circuit also detects the presence of voltage across the load, signifying that the controlled switching device is causing power to be supplied to the load. The protective circuit removes power form the load when there is an absence of control signal and there is voltage across the load, indicating a failure of the controlled switching device.

Abstract: An N.times.N integrated optical interconnection apparatus capable of switching, multiplexing, or demultiplexing a large number of input and output wavelength channels achieves low levels of crosstalk and insertion loss. Two substantially identical N.times.M star couplers are connected by an optical diffraction grating comprising M unequal length waveguides spaced from one another by predetermined amounts. Each coupler comprises a dielectric slab defining a free space region between two periodic arrays of waveguides, each radially directed toward a virtual focal point. The arrays are configured so that their respective foci are located at a predetermined distance away from and outside the free space region to minimize phase errors caused by mutual coupling between adjacent waveguides. Specifically, the focal point of each array connected to each star coupler may be located so that it coincides with the phase center of the other array connected to each coupler.

Abstract: A technique of providing numerous distinct conductive patterns on a piezoelectric substrate is accomplished using only two masking apparatus. One masking apparatus defines a common portion or structure for each of the patterns. The second masking apparatus defines numerous distinct patterns, each corresponding to a different alignment position with respect to the common structure already formed on the substrate. One application for this technique is in economic production of coded SAW devices which may serve as coding or decoding devices, filters, or correlators, each of the SAW devices having a different individual code.

Abstract: A frame error detection system for SONET which operates in both the OC-3 and OC-12 modes. The frame detection circuit operates by examining the incoming data bit stream, which is in parallel form, detecting A1 and A2 bytes and if, in the OC-3 mode, three consecutive A1 bytes are received, followed by three A2 bytes, then framing is correct. If one of these bytes is missing, then there is an error in framing. The bytes, as they are received and processed by the system, are stored in a series of flip-flops and the output logic signal therefrom is indicative of the framing condition as to whether it is correct or errored.

Abstract: A frame detection circuit for SONET which operates in both the OC-3 and OC-12 modes. The frame detection circuit operates by examining the incoming data bit stream, detecting A1 and A2 bytes, and counting three consecutive A1 bytes immediately followed by three consecutive A2 bytes. Since the counters recycle upon reaching a three count, the circuit works for both the OC-3 and OC-12 modes.

Abstract: A hermetically sealed optical fiber lens arrangement, particularly for optoelectronic modules, includes an optical fiber which extends through a metal tubule and is fastened therein. The metal tubule is attached through a flange at an aperture in a wall of a module housing, and includes a spherical lens fastened in the module housing. The metal tubule supporting the optical fiber is adjusted in the flange by axially displacing it a preset focal distance from the spherical lens, and is fastened in the flange. The spherical lens mounting takes the form of a metal tubule and is adjusted at the frontal side of the flange adjacent to the housing by transverse displacement and fastened, so as to achieve optimum alignment of the optical axes of said arrangement, and the flange is hermetically sealed directly or through an annular projection of the spherical lens mounting to the modular housing wall.

Abstract: A process for making a thyristor device protected against breakover firing is to generate in the semiconductor body (1) of the thyristor an area (A) which has a lower breakdown voltage than the rest of the semiconductor body. This area is protected by suitable measures when the thyristor is overloaded. The invention features a process in which the area (A) of the semiconductor body (1) is irradiated locally with protons, with the proton energy being measured in such a manner that the maximum of the defect density and doping generated by the proton irradiation lies between the PN junction (15) of the first base region (9) and the second base region (10) and the half thickness of the second base region (10), and the semiconductor body (1) is subsequently heat-treated.