Abstract: A data transmission system and method employing either a renegotiated variable bit-rate ("RVBR") network or a renegotiated constant bit-rate ("RCBR") network. Within these networks, data transmission rates between a sender and a recipient are rapidly renegotiated as a function of previously stored data transmission rate information and system buffer levels. Such a system and method can be readily implemented within existing CBR and/or VBR network architectures. The RCBR and RVBR networks allow for the implementation of an intelligent data traffic management systems that are responsive to the rate at which new calls or requests for connections enter and leave the network, the frequency and duration of extended peak rate data bursts, as well as the occurrence of short duration data transmission peaks.

Abstract: An intermodulation distortion (IMD) detection system improves IMD reduction capability of power shared linear amplifier networks. In one embodiment, first and second power sharing networks, preferably Butler Matrices, are provided with a plurality of linear amplifier circuits coupled therebetween. A plurality of input signals are applied to respective input ports of the first power sharing network, with a portion of each input signal amplified by each amplifier circuit and then recombined in the second power sharing network so that each amplified input signal appears at only one output port of the second power sharing network. An antenna coupled to each of these output ports then radiates the amplified signal energy associated with one of the input signals. A test signal, which may be a dual tone signal, is applied to another input port of the first power sharing network, where it is split and amplified by each amplifier circuit.

Abstract: An optical isolator utilizes a pair of polarization selective elements, as for example birefringent wedges, and all integral Faraday rotator aligned therewith to perform optical signal isolation without introducing the polarization mode dispersion inherent in conventional polarization independent optical isolators. Optical isolation is accomplished by passing a forward-directed optical signal through a first birefringent element which separates the optical signal into two orthogonal states. The two orthogonal polarization states exchange identities upon entering the second birefringent element from the Faraday rotation element and are again deflected by the second birefringent element so that they emerge from the second element parallel to each other and, having traveled the same optical path length, witllout any polarization mode dispersion. Both polarization states of the reverse propagating optical signal are sufficiently angularly deflected to avoid coupling with the optical signal path.

Abstract: A symmetric procedure avoids the problems with prior art systems using modifiers with master keys and generates a secure session key from a secret master key and an additional pair of randomly selected signals. The secret master key is known to both parties: one at station A and one at station B. One randomly selected signal of the pair is generated by the party at station A while the other signal in the pair is generated by the party at station B. In one embodiment, a random number signal sent by each one of the parties to the other is encrypted before transmission and decrypted upon reception. Both encryption (at one station) and decryption (at the other station) employ symmetric key cryptographic systems which use the secret master key. The session key is then formed by a commutative combination of both random number signals.

Abstract: An air moving device such as an axial cooling fan comprises a rotatable shaft assembly and a plurality of fan blades coupled to the rotatable shaft assembly, each of the fan blades having a trailing edge when the rotatable shaft assembly is rotated in a given direction. In accordance with one illustrative embodiment of the invention, at least one of the fan blades has a sound reducing material attached thereto alongside the trailing edge thereof. The sound reducing material reduces aeroacoustic noise by reducing the aerodynamic effect that occurs when turbulence produced by the pressure differential between the two sides of one blade comes into contact either with the trailing edge of the given blade which created it, or, more significantly, with the following blade, at or near that blade's trailing edge.

Abstract: An apparatus and method for reducing the runlength of dropped packets in multiple access cellular communication systems. The invention is particularly well suited for use in time-division multiple access (TDMA) systems such as, for example, shared time-division duplexing (STDD) systems, and TDMA/TDD systems with speech activity detection (SAD). Frame time or frequency slots for communicating information are allocated to a first set of active users. A second set of active users which are not allocated a slot in a given frame are identified. At least one of the users in the second set which remains active in a subsequent frame is provided with a priority in obtaining an allocated slot in the subsequent frame. In one embodiment, the slots allocated to particular active users in the given frame are shifted by at least one slot position if the same users are allocated slots in the subsequent frame.

Abstract: Disclosed is an apparatus for digitizing an electromagnetic input signal having frequency components within at least first and second segregated frequency bands, particularly useful in a wireless communications system. The apparatus includes a filtering circuit arrangement for passing only frequency components of the input signal substantially within the first and second frequency bands, to provide a filtered signal having a spectrum with spectral components below a predetermined power level within a frequency gap between the first and second frequency bands. An analog to digital (A/D) converter samples the filtered signal at a sampling rate sufficient to provide a digitized output signal with a frequency spectrum corresponding to that of the filtered signal and also with a replica of spectral components of one of the frequency bands appearing within the frequency gap.

Abstract: A motion detection camera system which may be used as a security camera includes an active pixel imaging system operable in a video and differential mode connected to a mode activation circuit that controls the imaging system mode. In the video mode, the imaging system generates an output signal containing information of a viewed area on a frame by frame manner. In the differential mode, the imaging system generates a differential output signal containing information consisting of the differences in the viewed area between adjacent detected frames. Normally, the imaging system camera is operated in the differential mode. If no motion occurs in the viewed area, the corresponding differential output signal representing the interframe differences will have a constant signal level. Upon detecting that the differential output signal deviates by greater than a threshold level indicating motion in the viewed area, the mode activation circuit causes the imaging system to operate in its video mode.

Abstract: A global satellite communication network is described. The global satellite communication network comprises a plurality of polar communication loops and a plurality of longitudinal communication loops. The polar and longitudinal communication loops are formed in three dimensional space. Each polar communication loop includes a plurality of nodes each bidirectionally communicating with adjacent communicating nodes in the polar communication loops. Each longitudinal communication loop includes a plurality of nodes each bidirectionally communicating with adjacent communicating nodes in the longitudinal communication loops. Each longitudinal communication loop is in communication with each polar communication loop via a node which is common to both the longitudinal communication loop and the polar communication loop.

Abstract: A duplexer, useable to interlink the receiver, transmitter and antenna units of a microwave transmit/receive system takes the form of a "T" junction coupling device and three coaxial lines extending from junction ends at such device to coaxial end connectors on the ends of such lines away from such device. The "T" junction coupling device comprises a copper block having a central cavity and three bores leading into such cavity, a copper cap to close the top of such cavity, a copper disc disposed in said cavity away from its walls and containing a central space and three passages leading into said spaces and corresponding to said bores, and three brass ferrules for such lines. The ferrules are seated on the junction ends of such lines and are soldered to their outer conductors and are pressed fitted into the three bores. The inner conductors are received in the three passages in the disc and are all soldered thereto.

Abstract: A method of field oxide formation which creates field oxides of comparatively uniform height between differently-spaced oxidation masks is disclosed. A patterned oxidation mask, typically silicon nitride, (possibly with underlying polysilicon) is formed. A blanket layer of polysilicon is formed and etched back, thereby filling spaces between closely-spaced portions of the oxidation mask and fillets between less-closely spaced portions. A thermal oxidation is performed to produce a field oxide. The field oxide has comparatively uniform height despite differences in oxidation mask spacing.

Abstract: A data transmission system includes a low bandwidth two way transmission network which is employed to arrange access to and use of a wide bandwidth bearer channel to facilitate the transmission of data at a wide bandwidth enhancing the efficiency of data transmission. In one embodiment, a low bandwidth telecommunication service is used to set up a wide band channel connection on a wide band telecommunication service to allow the user to communicate high speed data without the necessity of overhead addressing and accessing communications on that channel.

Abstract: A patch panel having an array of openings therein and an adapter collar for mounting an optical fiber coupler in an opening. The collar has two body portions, one of which fits within the opening and the other of which buts against the front face of the panel. A coupler receiving opening extends through the body portions and has webs therein providing locking surfaces for the coupler. The collar is mounted and locked in the opening by means of cantilevered arms biased outward from the body portions, and a locking member is insertable between the arms and the body portions to prevent accidental or inadvertent release of the collar from the panel.

Abstract: A tab (22) at the edge of a panel (10) may be advantageously sheared by transporting the panel into an in-line shear (30). As the panel is transported into the shear, an adjustable rail (52) engages the tab (22) to guide the panel to maintain its orientation. The rail (52) is adjusted after the tab (22) has been sheared to now engage the panel (10) along its edge formed by the removal of the tab. In this way, the rail (52) can guide the panel upon transport from the shear.

Abstract: A forward error correction system adaptively changes the number of parity bits, bytes or packets transmitted to a receiver, based on previous error patterns experienced recently in the reception of original and parity bits, bytes or packets by that receiver.

Abstract: A wide variety of services both narrow band and broad band are provided to wireless stations both fixed and mobile by a flexible intelligent ATM base station. Such a base station provides two-way integrated voice, wireless date, wireless multimedia, and compressed video services to a wireless subscriber using different narrow band and wide band Common Air Interfaces (CAI). Uplink service includes narrow band signaling and bearer information signaling. By having a single base station perform these services, the number of station sites, required for a given level of service, may be significantly reduced and the spectrum utilization may be significantly increased.

Abstract: A fire retardant cable for use primarily as a riser cable in buildings has a plurality of groups of twisted pairs of conductors arranged in a "honeycomb" structure. Each conductor comprises a metallic conducting member encased in a single layer of a non-flame retardant polyolefin material such as high density polyethylene. The groups of conductors are surrounded by a jacket of flame retardant poly(vinyl chloride) material.

Abstract: A self-calibration system and method (125) determines the adequacy of an interferometer angle .phi. and surface curvatures in an inspection system (90). The inspection system (90) can contactlessly measure the disparity between two surfaces, such as the undercut or protrusion of an optical fiber (26) relative to a surrounding support material (36) at the endface (79) of an optical fiber termination (37). The inspection system (90) measures an offset of the fringe (113') in the image over the target (25') in the image (111a, 111b, 111c) in order to determine the disparity. In structure, the inspection system (90) has a measurement apparatus (91) with an interferometer (98) situated at the angle .phi. relative to the target (82) controlled by a machine vision system (92) for determining the degree of disparity. Further, the machine vision system (92) preferably employs the self-calibration system and method (125).

Abstract: Tungsten plugs are formed by passivating a substrate having a contact hole with SiH.sub.4, forming a nucleation layer on the passivated substrate by reducing WF.sub.6 with SiH.sub.4 at relatively low pressures and depositing tungsten to substantially fill the contact hole by reducing WF.sub.6 with H.sub.2 at relatively high pressures. Alternatively, rapid thermal annealing is used to cure pinhole defects in a titanium nitride layer on a substrate to avoid the formation of unwanted tungsten volcanoes.