Abstract: The system to pre-qualify copper subscriber loops for high bandwidth access service determines electrical characteristics of a subscriber line served by a central office switch from a location remote from said subscriber line absent a direct metallic connection exclusively to said subscriber line. This is accomplished where the subscriber line has subscriber equipment connected thereto at an end distant from said central office switch by establishing a communication connection through the central office switch between the service provider and the subscriber equipment connected to said subscriber line. In response to the establishment of this communication connection, electrical signals, comprising subscriber or network generated tone signals, are applied to the subscriber line to enable the service provider to determine the electrical characteristics of the subscriber line by analyzing the received tone signals.

Abstract: A reflective element, such as a mirror, includes a substrate and a reflective layer formed thereon. The substrate comprises at least one thixotropic metal alloy, which is injected into a mold to form the shape desired for the reflective element. The reflective element may also include an interface layer comprising a thermoset material, such as an epoxy resin, formed between the substrate and the reflective layer to increase the smoothness of the substrate.

Abstract: Disclosed is a method and apparatus for facilitating detection of satellite signals using a sequential search technique. The sequential search technique is a knowledge based technique that sequentially searches for satellite signals based on search messages and information accumulated during prior searches to effectively reduce the area and code phase search range in which a GPS receiver searches for the satellite signals, thereby enhancing detection of the satellite signals.

Abstract: Discrete tomographic apparatus comprises an electron microscope for irradiating a sample comprising an atomic lattice structure. Line count data is obtained for the main directions of a cross section of the sample. A non-linear programming algorithm is applied to obtain probabilities of occupancy of lattice sites by atoms of the sample. The non-linear programming algorithm comprises an iterative application of the expectation/maximization algorithm upper bounded by the constraint that each variable is valued at less than or equal to one. Once the algorithm is iteratively applied a phantom image of the cross section of the sample is generated. The cross sectional area may be less than one thousand atoms by one thousand atoms.

Abstract: A method that rapidly and precisely determines the geographical location of areas of high concentration of usage (hot spots) and areas of poor RF frequency reception (dead spots) by measuring the number of failed call attempts, dropped calls and the like and comparing them to the identification of a mobile station and its location are recorded as record at selected points during a call. If a high number of uncompleted calls or dropped calls are recorded, then the base station can use the last known location of the wireless units involved to circumscribe an area in which the hot spot or dead spot occurs.

Abstract: A method for varying the resistance along a conductive layer. The method including the step of removing at least a portion of a resistance-altering constituent diffused within the conductive layer.

Abstract: In a system for communicating an image, an image compression scheme is employed to encode the image to reduce the required bandwidth for transmitting same. For example, this compression scheme includes performing, on the image, a discrete cosine transform (DCT), followed by quantization. To reduce the effects of coding artifacts occasioned by the compression scheme, in accordance with the invention, a filter arrangement which is matched to the coding of the image may be utilized to process a received image. The filter arrangement is designed to truncate each non-zero frequency component in the received image whose amplitude is lower than a certain threshold, which is a function of the quantization step size used.

Abstract: An optical switch comprises a programmable optical polarization unit (POLCON) which receives an input optical signal and selects an output signal polarization in response to a control signal. A polarization beam splitter (PBS) splits the selected polarization signal from the POLCON into a first and second orthogonally polarized signals. A feedback circuit couples a feedback signal indicative of the optical signal strength of at least one of the orthogonally polarized signals back to the POLCON which uses it to adjust the output signal polarization. The optical switch may be used with input optical signals having fixed or varying polarizations by utilizing a single or two feedback signals, respectively. The optical switch may be used as an optical Add/Drop unit or incorporated as part of a wavelength division multiplexed (WDM) signal Add/Drop unit.

Abstract: A low power differential comparator wherein the input stage bias is used not only to set a bias level but is also used to set the hysteresis level of the differential comparator circuit. The positive and/or negative inputs to the differential comparator circuit are referred to ground to reduce the total DC current draw, e.g., by a factor of 7. The multiple use of the input stage bias and grounded connections to the positive and/or negative inputs reduce the overall current requirements of the differential comparator circuit substantially while maintaining full operating speed as compared to conventional differential comparator circuits. In one embodiment using the low power differential comparator circuit, a clock receiver implements hysteresis which is relatively independent from variations in environmental factors such as temperature, and from power supply variations. In this embodiment, the input stage of a low power comparator circuit is biased by the output of a bias circuit.

Abstract: An application programming interface (API) is described that allows creating or destroying one or more pairs of data structures for asynchronously passing between the operating system and a network application pointers to packet buffers mapped to both parties.

Abstract: A non-blocking crossbar for packet based networks and a method of operation thereof. In one embodiment, the non-blocking crossbar includes: (1) n inputs, n numbering at least two, (2) n outputs, each of the outputs having a destination first-in, first-out buffer (FIFO) and n crossbar FIFOs interposing corresponding ones of the n inputs and the destination FIFO, and (3) a scheduler configured to cause a packet to be transmitted from one of the inputs toward one of the outputs only when both the destination FIFO associated therewith and an interposing one of the crossbar FIFOs are available to contain the packet.

Abstract: An optical lens for use with an optical bench. The lens has a diffractive element which provides an angular offset to radiation incident on the lens. The offset substantially compensates for an undesirable focal point location caused by a variance between an integral component position on the bench and a desired position. The lens is particularly useful for an integral component position dictated by the bench crystal structure. In an illustrative embodiment an aspheric diffractive element deflects incident radiation by an amount in the range of about 8° to about 12°.

Abstract: A system and method that overcomes the deficiencies of prior optical data communication systems for local area networks by employing a centralized controller in conjunction with a robust protocol and contention scheme. This combination facilitates the transport of data between a number of optical nodes without collision. The invention is particularly suited to transmissions between several mobile optical nodes and one or more stationary network infrared collector/transmitters, allowing communication with the network as the mobile nodes roam from the vicinity of one network infrared collector/transmitter to the next.

Abstract: An object-oriented filter for filtering video images prior to video encoding is disclosed. The object-oriented filter is configured to include an image parameter extractor, a filter selector, and a filter. The image parameter extractor analyzes the input video sequences to map the location of pixels associated with one or more image parameters. Once the pixels associated with the image parameters are mapped, the filter selector ranks the identified image parameters based on their overall importance to the video sequence, and then selects a filtering factor for adjusting the strength of the filter used to filter the pixels associated with such identified image parameters. Thereafter, the pixels associated with each of the image parameters are filtered using the filter strength selected by the filter selector.

Abstract: A method and apparatus for estimating the signal-to-noise ratio in Orthogonal Frequency Division Multiplexing (OFDM) and Discrete Multi-tone (DMT) systems is disclosed. In all OFDM and DMT systems, the transmitter uses an Inverse Fast Fourier Transform (IFFT) of a significantly longer length than the number of sub-carriers that are used for information transmission (i.e., the active sub-carriers). The additional IFFT buffer locations (i.e., the inactive sub-carriers) are filled with zeroes. At the receiver, after the FFT operation, the active sub-carriers will contain the signal plus noise information whereas the inactive sub-carriers will contain only noise.

Abstract: A combinatorial approach is disclosed for analyzing a class of plurally parsable dictionaries for predictable, discrete, memoryless sources. A class of plurally parsable dictionaries are disclosed for a binary, memoryless source that outperforms the Tunstall code, when the probability of one of the symbols having a binary value of zero is sufficiently close to one. Given the probability of a symbol having a value equal to zero, p0, and the desired size of the dictionary, M, a dictionary is derived that provides. better compression than the Tunstall dictionary, if such a better dictionary exists. A Tunstall dictionary is initially selected having a size M—n, where n≧1. Thereafter, n all zero entries are added to the Tunstall dictionary. For the case where n equals one, the entry is comprised of a string of l zeroes. An equation is provided for obtaining the value of l. The improved dictionary is created by adding the all zero words (0l word for n=1) to the selected Tunstall dictionary.

Abstract: In accordance with the present invention, a duplex radio communication system comprises an Interrogator which generates a radio signal to at least one remote Tag. The remote Tag receives the radio signal. The Tag then generates a subcarrier signal, and using Quadrature Phase Shift Keying (QPSK), modulates an information signal onto the subcarrier. A Backscatter Modulator, using this modulated subcarrier, modulates the reflection of the radio signal, the reflected signal being a reflected modulated signal. The Interrogator receives and demodulates the reflected modulated signal to obtain the information signal. In one embodiment, demodulation utilizes a homodyne detector. In another embodiment, the Interrogator modulates an information signal onto the radio signal, transmits that modulated radio signal to the Tag, and the Tag demodulates that modulated radio signal to recover the information signal.

Abstract: The present invention generally relates to the field of optical transmission and particularly to a method and an apparatus for controlling the optical power of an optical transmission signal in wavelength division multiplex optical transmission system (WDM system). It is known to add one additional channel to the optical transmission signal of WDM systems, for controlling the power of the optical transmission signal. The optical power of the control channel is controlled to keep the total optical power of the optical transmission signal constant, e.g., if a channel of the optical transmission signal fails, the optical power of the control channel is increased. To change the optical power of the control channel usually the injection current of a laser which generates the control channel is changed as the laser is operated in the continuous wave mode. This causes the disadvantage of cross talk which influences the optical transmission signal.

Abstract: In accordance with the invention, a waveguide laser or amplifier having a peak absorption wavelength is provided with pump emitters having wavelengths deliberately offset from the peak absorption wavelength. The offset wavelengths of the emitters are chosen to enhance the thermal stability of the laser or amplifier. In one exemplary embodiment, the laser or amplifier is pumped by a bimodal distribution of emitters.

Abstract: A method and system for determining the high speed data service capability of a subscriber line includes sending an embedded test signal to a subscriber line. A reflected signal received in response to the test signal is analyzed for determining transmission characteristics of the subscriber line. Based on the reflected signal, a determination about the high speed data service capabilities of the subscriber line is made and stored for future reference.