Abstract: Apparatus and a method for testing tiered digital multiplexing apparatus. To test a primary train of tiered demultiplexers, a data path assurance train of demultiplexers and a selector is used to generate a demultiplexed signal for comparison with a primary demultiplexed signal. To test a primary train of tiered multiplexers, the output of the final multiplexing stage is connected to the input of the data path assurance train of demultiplexers to generate a demultiplexed signal for comparison with a primary input signal to the primary multiplexer train. Advantageously, a simpler, more reliable, and less expensive data path assurance circuit using the same types of components as the primary multiplexers and demultiplexers can be used to detect failures in these primary units as well as the data path assurance circuit.

Abstract: Disclosed is apparatus for mounting a cable within an electronics enclosure, such as a network interface unit, which includes a splice chamber. A recessed portion is formed in one surface of the chamber, and a tie bar is formed across the recessed portion to provide a gap. A tie wrap is threaded through the gap and tightened around the cable to secure it to the surface. A grommet can also be mounted at the opening to the chamber. The grommet is made of a compliant material which has a series of perforations defining a plurality of non-concentric circles, and a series of perforations defining radial lines. A number of circles can be removed approximating the diameter of the cable, and segments formed by the radial lines can be used as flaps to prevent dust or other undesirable material from entering the chamber.

Abstract: A variable ring count device in customer premises equipment is provided and includes a processor, a call related information detector/receiver in communication with a telephone line and a call related information directory in communication with the processor. The call related information directory associates pre-set call related information with a corresponding ring count. The processor is operable for an incoming call to compare call related information for the incoming call to the pre-set call related information in the call related information directory, and to determine a ring count for the incoming call based on a correlation between the call related information and the pre-set call related information in the call related information directory.

Abstract: We have recognized that in a Wavelength Division Multiplex (WDM) ring network with a closed loop, the possibility of lasing at Amplified Spontaneous Emissions (ASE) wavelengths exists. In accordance with the present invention, we provide a technique for protecting against lasing in a WDM ring network comprising a plurality of serially connected node links, each node link including a segment of optical fiber and an access node site for adding or dropping one or more active wavelength channels to a transmission bandwidth of the network. The protection means changes the optical transmission characteristics of the transmission bandwidth of the network to ensure that the network loop gain at any wavelength is always less than the network loop loss.

Abstract: A semiconductor device and a method of manufacturing the semiconductor device. The device includes: (1) a substrate composed at least in part of silicon and (2) a film located over the substrate and having a substantial concentration of an isotope of hydrogen located in the film.

Abstract: A customer bridge, also known as a network interface device, is provided with structural features to deter tampering with, or unauthorized use of, phone services. The customer bridge includes first and second extended flanges located on opposite sides of an RJ-11 jack. The first and second extended flanges include first and second through holes, respectively. A shackle may be passed through the first and second through holes and secured to a padlock to prevent removal of an RJ-11 plug from the RJ-11 jack, or to block access to an empty RJ-11 jack.

Abstract: A method and apparatus for generating and analyzing reduced-order models of linear circuits. The method and apparatus generates a characteristic tridiagonal matrix using a look-ahead Lanczos procedure and then checks the matrix for stability and passivity. If the matrix is not stable and passive, the matrix is modified via a partial Pade via Lanczos approximation algorithm and then rechecked for passivity and stability. The process is iterated until a passive and stable model is generated. When a satisfactory matrix is generated, a Pade approximant of a transfer function of the circuit is computed and the frequency response of this circuit is generated and displayed.

Abstract: For use with a power converter coupled to a regulation circuit and having a power switch and an auxiliary switch coupled thereto, a controller, method of operating the power switch and auxiliary switch and a power converter employing the controller and method. In one embodiment, the controller includes a voltage conditioning network, parallel-coupled to the power switch, capable of sensing a voltage across the power switch and developing a conditioned voltage. The controller further includes a drive circuit, coupled to the voltage conditioning network, adapted to provide a drive signal to control the auxiliary switch as a function of the conditioned voltage and a regulation control signal from the regulation circuit.

Abstract: An anti-fraud string cutter for a coin telephone instrument having a serpentine coin path. The string cutter is fabricated as a stack of notched, slit, sheet metal plates having alternately off-set flat and wavy teeth which are adapted to snag and cut, between adjacent ones of the plates, any string threaded through said coin path by a fraudulent user. String cutters are advantageously to be mounted adjacent to one of the cusps of the serpentine path and above the coin return hopper.

Abstract: The simulation of the output of a crystal circuit is greatly accelerated to steady state by altering the conventional model of a physical crystal to include a constant current source. The constant current source has an oscillating output which is temporarily inserted into the simulated circuit by driving current for only a certain length of time, e.g., for only once cycle of a frequency chosen to correspond to the resonant frequency of the crystal being modeled. The output current of the current source is thereafter forced to zero to effectively remove it from the simulated circuit. The peak current amplitude of the current source is initially selected based on parameters of the crystal being modeled, and estimated by formula, then empirically adjusted if necessary to obtain fast simulation results of the crystal circuit to a steady state. A look-up table can be implemented in SPICE or any other circuit simulation tool to implement the current source in the crystal model.

Abstract: An arrangement for paging mobile telephone units (MTU) in a cellular mobile system that conserves paging resources. If the identity of the most recent cell in which the MTU was located matches the identity of the cell wherein the MTU was location on the previous registration, then an initial page covering only the cell of the most recent call location for the target MTU, and the neighboring cells for that cell, is used. Advantageously, since the likelihood that the MTU is still within that cell or its neighbors is high, so that paging resources are conserved by paging in only a small number of cells.

Abstract: In low-voltage circuits, there is often insufficient voltage to use a current source to bias a transconductance amplifier stage. This is particularly true in mixers where a switching circuit must be stacked on top of the transconductance input stage. One way around this problem is to get "double-duty" out of the input differential pair, using it both for gain stage and for DC bias. This is done by AC coupling in a high-frequency input signal, while using a low-frequency, DC-coupled circuit to establish the proper bias level. One common technique is to use a simple current mirror scheme to establish the DC level. Proper biasing using this technique requires good matching of resistance. In some implementations of transconductance amplifiers, particularly those that use inductors as degeneration elements, series resistance of the inductor and interconnect resistance can cause significant errors in the bias current.

Abstract: A network for multi-bit word parallel communication between optoelectronic chips on a two dimensional array of optical input and output channels carried on a single dimension of optical fibers. Each bit of a word is carried on a different wavelength and the multiple wavelengths carrying a word are wavelength multiplexed onto a single optical fiber. Multiple fibers can be joined into a one dimensional array of fibers. A transceiver for transmitting and receiving along the optical data channels comprises an array of modulators powered by individual wavelength light beams, either from individual monochromatic light sources and a light beam from a single broadband light source made to pass through a diffraction grating. The modulators are positioned so that each modulator reflects a different wavelength light beam, thereby providing multiple optical channels. Alternatively, multiple wavelengths are generated from CMOS integrated light sources.

Abstract: In one embodiment, an optical transmitter, which has a modulator disposed between an pair of optical amplifiers, exhibits reduced carrier-to-noise ratio and relatively high powers. In another embodiment, an optical amplifier is disposed between the laser carrier source and the modulator, but the post-modulator amplifier is omitted. Application of the transmitters to analog systems (e.g., CATV) and digital systems is described.

Abstract: Monitoring of the wavelength and power in an optical network is realized by including a wavelength router in which output ports at particular locations are included to derive samples for the monitoring. A periodic variation in the optical length of the arms of the grating in the router is used to focus additional power at these selected locations. Such a router can also be used for multiplexing and demultiplexing optical signals.

Abstract: Method and apparatus for providing visualization of information contained in a data set is provided. The data set is arranged in first and second categories of data, and a selection variable and a summary variable are chosen from the second category of data. A unique value is located in the first category of data which matches each selection variable, and a statistical summary of the summary variables is computed for each located unique value in the first category of data. The resultant display is based on the computation of the statistical summary.

Abstract: A converter includes at least two series coupled integrators, a comparator and a feedback element. The converter provides digital domain scaling so that an output signal is a scaled version of an input signal based on a feedback factor of the feedback element.

Abstract: A compact multiwavelength laser arrangement includes a reflective waveguide grating combined with two arrays of reflecting waveguide elements located in separate focal regions formed by the grating. The laser uses a folded imaging arrangement with nonoverlapping focal regions that eliminates unwanted resonances of previous reflective arrangements. The laser's advantages over existing transmissive laser arrangements include reduced size, faster response time, and increased number of wavelengths.

Abstract: A quantum cascade (QC) laser has a multilayer core region comprising alternating layers of a first and a second semiconductor material, with lattice constants a.sub.1 and a.sub.2, respectively. The first material is selected such that a.sub.1 >a.sub.0, where a, is the lattice constant of the substrate (typically InP), and the second material is selected such that a.sub.2 >a.sub.0. The materials are also selected such that the conduction band discontinuity .DELTA.E.sub.c between the first and second materials is greater than 520 meV in absolute value. The multilayer core comprises a multiplicity of essentially identical multilayer repeat units. The layer thicknesses and materials of the repeat units are selected to substantially provide strain compensation over a repeat unit. QC lasers according to this invention preferably comprise a distributed feedback feature, (e.g.