Abstract: A telephone with an automatic muting circuit that mutes the microphone in response to detection of speaking pauses of the local user to reduce noise due to acoustical feedback that are detected by comparing the waveforms from the microphone and the audio speaker after being amplified by amplifiers with automatic gain control circuits to the same level with speech subtractor. During pauses when the signals compared are substantially the same, then automatic muting circuit is activated by the speech subtractor to mute the microphone but when the local user speaks into the microphone the subtraction of the waveforms does not yield a null result and the microphone is unmuted.

Abstract: A method for controlling data packet traffic flow over a bus interconnecting two or more nodes in a data communication system, each node having a unique address associated therewith and having a respective buffer memory for temporarily holding incoming data communicated thereto, each node further being capable of multicast sending of data packets over the bus to one or more nodes having respective addresses logically associated a unique address, the method comprising: checking current available buffer memory occupancy upon receipt of a data packet, the node being capable of outputting for transmission on the bus a first flow control indicator message when the data temporarily stored in the buffer memory is above a first buffer occupancy threshold associated with data of a first priority type, and a second flow control indicator message when the data temporarily stored in the buffer memory is above a second buffer occupancy threshold, the second buffer occupancy threshold being greater than the first occupancy

Abstract: A high speed and low power digital circuit for producing an output responsive to a plurality of input data signals, such as a multiplexer or a latch includes one or more data switching elements. Each of the switching elements is a differential transistor pair having one transistor driven by a control signal and the other transistor driven by a data signal. The signal levels for the data and control signals are interleaved so that each control signal turns on and off the effect of the data signal on the current flow in the switching element. The circuit structure avoids emitter coupling more than two transistors at any point in order to reduce the capacitance at critical nodes and consequently increase switching speed. By providing two switching elements with data transistors connected to a common pull-down resistor, two data signals, and a complementary pair of control signals, a multiplexing function can be performed.

Abstract: A cooling system for a circuit board employs a heat-conducing channel within the board. The channel is thermally coupled to an electrical device mounted on the board, and leads to an edge of the board. The edge of the board is coupled to a heat-dissipating can. The use of channels leading to the edges of the board allows a single can to dissipate heat for a plurality of boards and a plurality of devices.

Abstract: A sealing arrangement for use in a gas delivery system to a rotating tubular member has first and second disposable seals spaced apart to form a sealed buffer zone within the rotating tube. A supply coupling is connectable to a source of buffer gas and has an insert member which has one or more channels for routing the buffer gas into the buffer zone. The supply coupling is also connectable to a low pressure source and the insert member has one or more channels for routing the gases contained in the buffer zone out of the zone to the supply coupling, thus creating a continuous circulation of buffer gases.

Abstract: It has been found that through the use of ferrocene or iron pentacarbonyl based compounds, it is possible to produce semi-insulating epitaxial layers of indium phosphide-based compounds by an MOCVD process. Resistivities up to 1×109 ohm-cm have been achieved as compared to resistivities on the order of 5×103 ohm-cm for other types of semi-insulating epitaxial indium phosphide.

Abstract: An article for de-embedding parasitics and/or acting as an on-wafer calibration standard is disclosed. In particular, some articles in accordance with the present invention provide structures on integrated circuits that mitigate the severity of parasitics Furthermore, some articles in accordance with the present invention are well-suited for use with conductive substrates that operate at high frequencies. In an illustrative embodiment, conductive elements are used to construct structures near and/or around the leads on the integrated circuit. When the structures are grounded, the structures function to (at least) partially shield the leads to and from the DUT in a manner that is analogous to stripline, microstrip and coaxial cable. Because the electric fields emanating from the leads terminate in the grounded structure and not in the conductive substrate of the integrated circuit, the severity of the parasitics in the leads in mitigated.

Abstract: The present invention relates generally to the field of optical transmission and particularly to a method and a system for controlling optical amplification in wavelength division multiplex optical transmission. WDM systems currently under development will have eighty or more channels, i.e., modulated optical signals with different wavelengths (known as Dense Wavelength Division Multiplexing, DWDM). These DWDM systems are demanding optical amplifiers which, especially considering the cascadation of a plurality of optical amplifiers along the transmission path of the DWDM system, have only very limited tolerances in certain parameters. Among these parameters gain flatness and gain tilt are of special importance. The present invention discloses a method and a system which make use of auxiliary optical signals having a given power level which is equal for all auxiliary signals.

Abstract: A dynamically and chromatically variable transmissivity apparatus (e.g., a channel equalizer or an add-drop circuit) controls channel powers in wavelength-division multiplexed systems. The input WDM signal is split into two components, in one component a phase shift is added to the wavelengths needing equalizing, the two signal components are then recombined. The phase shift added at each wavelength determines the amount of equalization obtained for that wavelength. For a decrease in equalization (i.e., attenuation) range the apparatus exhibits a decrease in insertion loss.

Abstract: A compensation circuit for a DC—DC converter having a low voltage output line and a plurality of high voltage output lines applied to a plurality of loads includes an adjustable impedance source connected to the low voltage output line. The impedance source generates a feedback control signal to the DC—DC converter used to control the transformer duty cycle. A sensing circuit is connected to the plurality of high voltage output lines for generating a control signal which represents variations in the output voltages of the high voltage output lines. The control signal is applied to the impedance source to thereby regulate the feedback control signal which in turn provides regulation for the high voltage output lines.

Abstract: The modem of a portable computer device draws a portion of its required power from the telephone line using a low noise switching power supply. The switching power supply can alternatively or additionally assist in keeping the battery of the portable computer device charged. The generation or propagation of electrical noise on the input telephone line is minimized by actively maintaining a constant input impedance from the telephone line to the modem. In one embodiment, a switchable shunt impedance is placed in parallel with the input to a PWM switching power supply and actively controlled to maintain the impedance of the input of the PWM switching power supply constant to the extent that a constant current draw is maintained.

Abstract: First and second wafers are micromachined by standard integrated-circuit fabrication techniques to respectively make first and second component parts of a variable capacitor. A thin flexible membrane in the first wafer is integral with and mechanically supported by the first wafer. A metal pattern on the first wafer includes a first capacitor plate on the membrane. In the second wafer, a well is formed. A metal pattern on the second wafer includes a second capacitor plate in the well. By bonding the two parts together face-to-face, the capacitor plates are positioned in spaced-apart alignment with each other. External electrical connections to the plates are made via bonding-pad portions of the metal patterns on the wafers. In response to electrical control signals, the metal plate on the membrane can be moved toward the other plate, thereby selectively changing the capacitance of the assembly.

Abstract: A multiple differential pair circuit is disclosed having a transconductance, gm, proportional to the bias current, I0, for any transistor technology. The transistors utilized to construct each of the differential transistor pairs in a multiple differential pair circuit operate in a non-exponential voltage-current (V-I) region. As multiple differential pair circuits are linearized, the effective transconductance, gm, becomes (i) linearly dependent on bias current, and (ii) insensitive to the voltage-current (V-I) characteristics of the utilized devices. Methods and apparatus are disclosed that provide a linear transconductance, gm, with respect to the bias current, I0, using differential pairs of transistors where each transistor operates in a non-exponential voltage-current (V-I) region, such as MOS transistors.

Abstract: A silica body useful for forming an optical fiber preform exhibits an ultimate strength of at least 20 MPa at 10 wt. % water loss. The body attains this strength, it is believed, by precipitation of silica at the contact sites of adjacent silica particles, thereby forming neck regions. The resultant network provides the strength to the gel body, such that the body is capable of being dried under more severe conditions than a gel body formed by previous sol-gel methods and is also more robust toward handling. The controlled precipitation is attained by inducing gelation and initiating drying at a pH of about 10.5 or higher, at which silica remains highly soluble. By gelling and drying at this pH level, the solubilized silica appears to precipitate in a controlled manner at the point of contact of adjacent silica particles, since such sites are the minimum free energy sites for precipitation.

Abstract: Digital data is stored in an analog memory device using coded modulation techniques. The memory device includes a number of memory cells, each capable of storing one of a number of different levels. A given set of b information bits to be stored in the memory device is first coded in a convolutional or block coder to generate a set of coded bits which includes more than b bits. The set of coded bits is then mapped to one or more corresponding levels, and the one or more levels are each stored in a separate cell of the memory device. In a one-dimensional embodiment, the coding may involve applying a rate 1/2 convolutional code to i least significant bits, i=1, 2, . . . , and mapping the resulting b+i coded bits to one of 2b+i distinct levels in a one-dimensional AM signal set.

Abstract: A server in a telecommunications system is disclosed that prioritizes message signals queued for transmission over a telecommunications channel. A server in accordance with the present invention generalizes a wide range of specific queue disciplines into: (1) a generic sequence, and (2) a set of scalar parameters used in the sequence. Thereafter, the server is capable of mimicking any one of many specific queue disciplines (e.g., FIFO, LIFO, etc.) by appropriately setting the values of the parameters and without changing the generic sequence.

Abstract: A set of identifiers (for example, the name of a party and the associated telephone number) is stored in the memory of telephone apparatus. Sequential retrieval of the stored identifiers is facilitated by the use of a prominent button that is oversized relative to the size of the buttons of a conventional telephone keypad. Retrieved identifiers are indicated visually, aurally, and/or tactilely. Selection of an indicated identifier initiates a call to the party represented by the identifier.

Abstract: In a laser such as a mode-locked or Q-switched laser, one of the resonator reflectors comprises a switchable Faraday rotator mirror coupled to a switchable magnetic field source. The operation of the laser is therefore controlled by the application of the magnetic field to the Faraday rotator device. When no magnetic field is applied, the device behaves as an isolator and thereby breaks the signal path between the resonator reflectors. When a saturation magnetic field is applied, the reflectors, disposed on opposite sides of the optical gain medium, thereby form a cavity such that lasing will occur. The device may be formed of discrete components or fabricated as an integrated optical device.

Abstract: An in-line optical fiber polarimeter comprises a plurality of fiber gratings and a single wave plate, disposed sequentially along a length of optical fiber. The fiber gratings are precisely oriented and have a predetermined grating period such that each grating functions to out-couple a predetermined portion of the optical signal passing through the polarimeter. A separate detector is associated with each grating to measure the out-coupled signal. The four Stokes parameters can be determined from the set of measurements and then used to determine to state of polarization of an optical signal passing through the polarimeter.

Abstract: Relates to apparatus and methods for permitting an agent of a utility or service bureau to access customer metering equipment before or during a conversation with the customer. For accessing before a call, while the customer is still on-book, an alert signal is sent to activate the telemetering equipment prior to establishing a voice connection. For accessing during the call, an alert signal is sent while the customer is off-hook. Advantageously, the measurement can be made in conjunction with the oral contact with the customer, thus making customer contacts more efficient and providing better service to customers.