Abstract: A first in, first out memory (FIFO) includes a multi-port memory array, which is accessed for read/write operations by activating a selected read or write word line. The read word line is controlled by a read shift register, and the write word line is controlled by a write shift register. In order to generate "full" and "empty" flags, the voltage state of read and write word lines are determined in "match circuits", which compare the locations of the read and write pointers. This eliminates the use of counters, and allows the shift registers and word line match circuits to be an integral part of a single-block regular structure. Furthermore, it allows the FIFO to be readily expanded to multiple numbers of words and bits per word.

Abstract: A method for effecting bandwidth-on-demand, multiple digital channel connections between network subscribers, wherein each of a series of call requests from a given network subscriber to a given recipient establishes a connection via a restricted tandem switching arrangement. The switches within the network facilitating this method are each programmed to utilize inter-switch paths having essentially equivalent electrical delays when effecting connections for calls dialed by network subscribers designated as bandwidth-on-demand users, resulting the virtual elimination of inter-channel differential path delays.

Abstract: A method for enabling the service of mobilies by a microcell, in a two tier cellular system, involves identifying a microcell coverage area and offsetting microcell signal strength for a time sufficient to allow a fast moving vehicle, desiring service and having entered the microcell serving area, to exit the microcell coverage area before the call is set up or handed off forcing the controlling macrocell to handle the call setup or hand-off. Hence, only the mobile radiotelephones of stationary and relatively slow moving vehicles are served by the microcell. There is a substantially offset-coverage overlap period between the locations where a mobile may be found during the offset interval or duration of the apparent reduced signal strength of the microcell and the microcell coverage area. Calls that could be serviced by the microcell are instead serviced by the macrocell because the mobile radiotelephone responds to the strongest signal. This loss in capacity is solved by reducing the offset-coverage overlap.

Abstract: In accordance with the principles of this invention, Pulse Code Modulation (PCM) signal streams are converted into Asynchronous Transfer Mode (ATM) cells for switching and transmission across a telecommunications network. Each cell carries one PCM sample of up to 48 different voice connections, the voice connections selected from the PCM data streams because they have a common destination. The cells are transmitted over ATM virtual circuits, each circuit transmitting one cell every 125 .mu.s. Advantageously, ATM transmission systems interface with PCM systems without adding appreciable delay and without requiring additional buffering. Advantageously, new voice paths can be established most of the time by using available slots in the cells of existing virtual paths.

Abstract: An optical fiber cable (20) includes a core (22) which includes a plurality of bundles (31, 31 ) of optical fiber (24) and a yarn-like strength member system (35) which is wrapped with an oscillated or unidirectional lay about the optical fibers. The strength member system also provides impact resistance for the fibers. A jacket (40) which may include a flame-resistant plastic material encloses the core with the outer diameter of the jacket being substantially less than that of typical optical fiber cables. Portions of the strength member system contact an inner surface of the jacket, an outer surface of which is the outer surface of the cable.

Abstract: In a time-space-time switching network that provides connections at a hierarchy of data rates, a path-hunt arrangement effects establishment of a switched connection of a given bandwidth as a collection of a plurality of connections of smaller bandwidths of different sizes. Connections are first found at the highest rate of the hierarchy to satisfy as much of the given bandwidth as possible. Then, connections are found at the lower rates to satisfy any remaining unsatisfied bandwidth. The path-hunt uses a hierarchy of status tables, corresponding to the hierarchy of rates, for each time-switching element of the network. The tables have entries that define availability of time slots--representing bandwidth of the tables' corresponding rates--between that time-switching element and a space-switching stage of the network. Connections are provided at the highest rate by finding matching idle time-slot entries in the high rate status tables for the two time-switching elements involved in the connection.

Abstract: Optical fiber drawn from preforms including sol-gel-derived glass is found to contain small refractory particles of the order of a micron in size. These particles initiate fiber breaks with the result that fiber may not meet proof-test tensile strength requirements. An effective separation method relies upon density and/or size difference from suspended sol particles for separation in the ungelled sol. A preferred separation procedure is centrifugation.

Abstract: A delay-locked-loop (DLL) controls the cutoff frequency of a filter in an exemplary mass storage servo control channel. The cutoff frequency is adjusted in response to a clock pulse which updates the DLL. Between pulses, the DLL holds its value, reducing power consumption. The DLL has a fixed delay (precision) and a variable delay cell producing two delayed outputs, one output a predetermined amount after the other output. The DLL locks the delayed pulses from the variable delay cell to straddle a delayed pulse from the precision delay. The filter has selectable resistors and capacitors for adjusting the frequency thereof. Substantially identical selectable resistors and fixed capacitors are in the variable delay cell. The DLL selects which resistors in the variable delay cell (and corresponding resistors in the filter) results in the straddled delayed pulses. The capacitors in the filter are selected for the approximate desired cutoff frequency of the filter.

Abstract: Despreading of the received signal in a CDMA system is provided using code coefficient sequences which are derived from those utilized by the system users to encode their respective symbols. Each derived code coefficient sequence is a function of the correlation between a different user's code coefficient sequence and the code coefficient sequences of all other users. Advantageously, this technique substantially reduces interference effects and is suitable for use in the despreader of differentially or nondifferentially coded CDMA systems.

Abstract: A particular electrostatic discharge (ESD) protection problem is faced when only n-channel output transistors are present, since there is no p-n junction that could serve to clamp positive ESD voltages, as would be the case if a p-channel output transistor were present. In the present technique, a capacitor couples a bond pad to the gate of a protective transistor that applies a turn-on voltage to the gate of an n-channel output transistor. In this manner, the output transistor itself is used to conduct the ESD current to a power supply conductor (V.sub.SS). In one embodiment, to assist in the turn-on of the n-channel output transistor, a transistor couples the bond pad to the n-tub in which the p-channel pre-driver transistor is formed. Conduction through this transistor raises the n-tub voltage when an ESD event occurs, thereby preventing the p-n junction of the p-channel driver transistor from clamping the turn-on voltage, which would limit the protection obtained by this technique.

Abstract: A method of forming an interlevel dielectric suitable for use with semiconductor integrated circuits is disclosed. The dielectric illustratively includes a triple layer sandwich of ozone-TEOS formed between two layers of plasma-enhanced TEOS. The dielectric is capable of filling high-aspect ratio trenches between runners. The ozone-TEOS is formed at a high pressure (approximately 90 Torr) to reduce hydrogen absorption. The reduced-hydrogen content ozone-TEOS is less susceptible to moisture formation and, therefore, presents less risk of degrading subsequently formed aluminum runners.

Abstract: A growable packet switching arrangement where the distribution network blocking probability is substantially reduced because the network has both switch links and chute links, and the network nodes include both a switching element interconnecting successive stage switch links and a plurality of non-switching, chute connections interconnecting successive stage chute links. A network node can transfer a packet, being received on a switch link, to any selected one of the chute connections of that node for transmission on a chute link. The network nodes are relatively simple and inexpensive because they store only the first few bits needed to route an ATM cell. The blocking probability is further reduced when the number of chutes per node is increased. The number of chutes may be based, for example, on the number of switch link inputs per node.

Abstract: A low-cost, low-power infrared digital communications system. The system overcomes the problem of infrared noise from interior lighting without using either a high-power infrared source or upmodulation of the source. The system includes an infrared collector which uses a non-directional concentrator to concentrate the infrared radiation and a circuit which detects the digital infrared signal in the noise by detecting the edges of the digital infrared signal. Devices in the system need not be aimed at each other, but need only be in line of sight of each other. The preferred embodiment employs the digital infrared signals to communicate between a set of digital devices and a breaker box connected to the telephone network.

Abstract: A technique employing a depolarized optical source to reduce the polarization dependent gain associated with the optical pump signal used to excite doped fiber amplifiers within an optical transmission system. Pumping the doped fiber amplifiers with a signal that has no single predominant linear SOP, equalizes the gain of the amplifiers. A particular embodiment of the invention includes a pump comprised of a passive polarization scrambler coupled to the output of a multifrequency optical laser. The simple, passive arrangement keeps overall system costs to a minimum and increases reliability.

Abstract: A particular electrostatic discharge (ESD) protection problem is faced when only n-channel output transistors are present, since there is no p-n junction that could serve to clamp positive ESD voltages, as would be the case if a p-channel output transistor were present. In the present technique, the output transistor itself is used to conduct the ESD current to a power supply conductor (V.sub.SS). To assist in the turn-on of the n-channel output transistor, a transistor couples the bond pad to the n-tub in which the p-channel pre-driver transistor is formed. Conduction through this transistor raises the n-tub voltage when an ESD event occurs, thereby preventing the p-n junction of the p-channel pre-driver transistor from clamping the turn-on voltage, which would limit the protection obtained by this technique. This technique is especially valuable for SCSI (Small Computer System Interface) chips, since only n-channel output transistors are used.

Abstract: Applicants have discovered that by heating cured polymer-coated fiber at temperatures of 100.degree. C. or more, they can enhance the fiber pullout strength by 25% or more. This postcure heating can advantageously be done off-line by placing loosely wound fiber in a heated oven. Alternatively the postcure heating can be done on-line by reel-to-reel passage of the fiber through a heated furnace. Preferred temperatures are in the range 100.degree. C.-300.degree. C.

Abstract: In accordance with the principles of this invention, Pulse Code Modulation (PCM) signal streams are converted into Asynchronous Transfer Mode (ATM) cells for switching and transmission across a telecommunications network. Each cell carries one PCM sample of up to 48 different voice connections, the voice connections selected from the PCM data streams because they have a common destination. The cells are transmitted over ATM virtual circuits, each circuit transmitting one cell every 125 .mu.s. Advantageously, ATM transmission systems interface with PCM systems without adding appreciable delay and without requiring additional buffering. Advantageously, new voice paths can be established most of the time by using available slots in the cells of existing virtual paths. This application relates to methods of establishing connections in accordance with the principles of the invention.

Abstract: Optical fibers (15) are supported within a bonded support member (16) having along opposite sides first and second grooves (14) which are parallel to the central axes of the fibers being supported. A first opening (22) is formed in a holder member (21) which includes a first projection (27). A cantilever spring member (23) is formed in the holder member having a second projection (27) opposite the first projection. The bonded fiber support member (16) is inserted into the opening such that the first projection engages the first groove (14) on one side, and the second projection engages the second groove (14) on the other side of the bonded support member. Thereafter, the bonded support member is locked into position and the holder biases one end of it against a polishing wheel (29) to permit polishing along a plane which is perpendicular to the axes of the optical fibers.

Abstract: The advantages of both active and passive modelocking techniques are realized within a single device by providing a p-i-n modulator formed at antiresonance within a Fabry-Perot etalon. The p-i-n modulator actively modulates light within the laser cavity by introducing periodic loss in response to changing voltages applied to the modulator. The p-i-n modulator includes an intrinsic region that is disposed between a p-doped region and an n-doped region. The modelocking performance of the p-i-n modulator is enhanced by the saturable absorber action of the intrinsic region.

Abstract: Applicant has demonstrated that by appropriately shaping the laser gain region one can control the polarization direction of semiconductor vertical cavity lasers and enhance their transverse mode selectivity. Specifically, configuring the transverse cross section to regions have a length-to-width ratio in excess of 1.2 favors emission with polarization in the long dimension at the fundamental mode. A cruciform structure favors emission with switchable orthogonal polarization. The transverse shape can be configured by dry etching a particular cavity shape in index guided lasers or by forming a shaped ion implantation region around gain guided lasers.