Abstract: A method for determining a contribution of burst noise to a bit error rate in a digital system for reception of an interleaved forward error correction-enabled digital symbol stream is described. The method is based on identifying errored symbols at a decoding stage, determining their positions in the interleaved stream, and performing a windowing operation such that the errored symbols located within the window in the interleaved stream are designated as burst errored symbols. A corresponding digital receiver and a digital transmission system are also disclosed.

Abstract: A test system for testing a communication system having a plurality of communication links is disclosed. The test system has a single tester for performing various measurement and diagnostic tasks on a single link. The test system also has a switching system for independently testing any link by coupling the tester into any one link. The tester is coupled into the link by coupling the tester input to the link's transmitter and the tester output to the link's receiver. The switching system couples the tester such that all remaining links of the communication system have a unique one of the plurality of transmitters coupled to a unique one of the plurality of receivers, whereby the operation of the communication system can be maintained while testing individual links.

Abstract: A fiber tray for routing and packaging an optical fiber is disclosed. The fiber tray includes a generally round central section, a lead-in section, and a lead-out section. All three sections are integrally formed out of a thin sheet of a material and coated with a tacky adhesive material for fiber retention. The adhesive allows for fiber removal and rerouting if required. The tray includes guiding walls, which establish the path of the optical fiber on the tray. The optical fiber is routed in a single layer on the tacky surface of the fiber tray. The optical fiber is supported and immobilized essentially along its entire length, including the length of the optical fiber routed on the lead-in and the lead-out sections.

Abstract: A method and apparatus are provided for detecting network impairments through tilt-normalized measurement data, the method including: collecting data for a network signal; computing a best-fit tilt for the collected data; performing tilt-normalization of the collected data responsive to the computed best-fit tilt; and determining whether the tilt-normalized data crosses a threshold, and if so, pattern matching the tilt-normalized data to detect a network impairment; and the apparatus including: an input unit for collecting data from a network signal; a tilt unit connected to the input unit for computing a best-fit tilt for the collected data and performing tilt-normalization of the collected data responsive to the computed best-fit tilt; and a pattern matching unit connected to the tilt unit for determining whether the tilt-normalized data crosses a threshold, and if so, pattern matching the tilt-normalized data to detect at least one network impairment.

Abstract: A printed image is disclosed wherein the image may be in the form of an array of magnetically aligned platelets or flakes that may by uniform in shape and size and wherein the flakes are arranged in a particularly manner to form optically illusive images useful as security devices, or useful in beam steering applications. In one embodiment of this invention printed array is disclosed a plurality of concentric rings of magnetically aligned platelets disposed upon a substrate in the form of a Fresnel structure, preferably a Fresnel reflector. Advantageously, since the magnetic field can be controlled with respect to strength and direction, one can easily design a field that will correct for spherical aberration that would otherwise be present in a typical Fresnel reflector. In other embodiments of the invention optically illusive images of funnels, domes and cones are printed.

Abstract: A tunable PLC optical filter having sequentially connected thermally tunable Mach-Zehnder (MZ) interferometers is described. The MZ interferometers, having free spectral ranges matching ITU frequency grid spacing, are tuned so as to have a common passband centered on the frequency of the signal being selected, while having at least one of the stopbands centered on any other ITU frequency. Any other optical channel that may be present at any other ITU frequency is suppressed as a result. The PLC chip, including a zero-dispersion lattice-filter interleaver stage, a switchable fine-resolution stage and, or a retroreflector for double passing the filter, is packaged into a hot-pluggable XFP transceiver package. A compensation heater is used to keep constant the amount of heat applied to the PLC chip inside the XFP package, so as to lessen temperature variations upon tuning of the PLC optical filter.

Abstract: Systems and methods for a network diagnostic component that is placed in-line between two nodes in a network to control the protocol with which two nodes communicate. The network diagnostic component receives a network data stream from a first node for communication with a second node. The network data stream is received by a receive component or module. The network data stream includes a portion that conforms with at least a first network protocol. The diagnostic component then determines that the first network protocol is not to be used to communicate with the second node. This determination is performed by a determine component or module. The diagnostic component modifies the network data stream so that the network data stream is in a form that is no longer recognized by the second node as being in accordance with the first network protocol. The modification is performed by a modification component or module.

Abstract: A modulation system and a method for generating a return-to-zero (RZ) optical data signal are provided. The modulation system comprises a Mach-Zehnder (MZ) modulator and a drive circuit, which includes a logic XOR gate and a differential amplifier. The logic XOR gate applies a logic XOR operation to a non-return-to-zero (NRZ) electrical data signal and an inverse of an electrical clock signal to generate an electrical intermediate signal. The differential amplifier differentially amplifies the electrical intermediate signal and an inverse of the NRZ electrical data signal to generate an RZ electrical drive signal. The drive circuit drives the MZ modulator with the RZ electrical drive signal to generate the RZ optical data signal.

Abstract: A data alignment system suitable for use in manipulating the positioning of a designated portion of a data stream transmitted by a high speed communications system, so as to facilitate further processing of the data carried by the data stream. The data alignment system includes a detector and an alignment component in communication with each other. In operation, the detector locates and identifies, in accordance with suitable instructions, the designated portion of the data stream. The alignment component then repositions, in accordance with suitable instructions, the designated portion of the data stream at a predetermined location within the data stream.

Abstract: Use of direct sequence spread spectrum test signals injected at the same time and frequency of active network services to perform non-interfering measurements in the forward and reverse path of a CATV plant. Ideally, a plurality of transmitters, each transmitting a test signal with a unique spreading code, whereby multiple overlapping test signals are received simultaneously at the receiver (CDMA).

Abstract: A remote testing device, including a cable modem circuit, requests an IP address from a remote cable modem termination system (CMTS) and receives back IP connection information including adaptive equalizer coefficients, which represent compensation and/or correction for transmission path noise. Using the equalizer coefficients, the remote testing device can determine a phase response, phase angles for each frequency increment over a channel bandwidth, and group delay.

Abstract: A method of forming pigment flakes includes using a deposition substrate having a plurality of regions; some of the regions are raised or lowered so that there is a level difference between each two adjacent regions. A coating deposited onto this substrate breaks along region borders when it is separated from the substrate. In one embodiment, the substrate includes first and second regions, wherein each of the first regions is in an abutting relationship with at least one of the second regions. All the first regions are at a first level and all the second regions are at a second level, and the difference between the first and second levels is greater than a predetermined value. The first and second regions are preferably square-shaped regions for manufacturing square flakes with practically no debris.

Abstract: A hoist capable of raising and lowering a truck bed to and from a truck frame. In certain example embodiments, a scissor-type hoist having a hydraulic cylinder base pivot located to improve hoist lift efficiency.

Abstract: In order to measure the performance of a DOCSIS upstream channel as well as to locate impairments, a special test signal is transmitted in a time slot of the upstream channel by a test instrument positioned anywhere within the CATV plant. A second test instrument, located at the termination point of the upstream plant, then detects, recovers, and processes the test signal in order to complete the measurement. The typical methods used to detect and recover bursted signals within a DOCSIS upstream channel use precise timing information transmitted in a corresponding DOCSIS downstream channel. Unfortunately, the downstream channel and thus the precise timing information are not always available to the secondary test instrument. The present invention also describes an apparatus and method for detecting a bursted test signal without the use of the DOCSIS upstream channel timing.

Abstract: A serializer device is used for generation, from a parallel digital signal, of a clock signal or a serial binary data signal having a pre-determined amount of jitter. A binary number having consecutive groups of ones and zeroes, when serialized by the serializer device, produces a clock signal. By varying the number of ones and zeroes on the binary number, a pre-determined amount of jitter can be generated. Use of sigma-delta modulation in combination with a phase-locked loop circuitry allows one to obtain a smoothly varying jitter of the output signal.

Abstract: An apparatus and method for frequency sweeping a CATV network, suitable for an upstream path frequency sweeping, is presented. A narrowband test signal is injected into the network by a generator coupled to a cable modem during a time interval allocated by the head end for the cable modem to transmit a modulated digital signal. The amplitude of the test signal is lower than the amplitude of the modulated digital signal, so as not to impair reception of said digital signal at the head end. The frequency of the test signal is swept, and the amplitude of the received test signal is measured. A telemetry or a digital signal transmission is used to communicated the values of the amplitude of the test signals between the injection and the measurement locations of the network.

Abstract: A method and apparatus are provided for testing susceptibility of a receiver to intermodulation distortion of a digital channel, the method including selecting a first digital channel from channels in a composite signal, determining a first power measurement from the first digital channel, determining a total power measurement from other channels in the composite signal, and determining susceptibility of the first digital channel to intermodulation distortion by comparing the first power measurement and the total power measurement with intermodulation distortion characteristics of the receiver.

Abstract: A method and apparatus for improving the accuracy of in-band OSNR measurements using a conventional polarization extinction or polarization-nulling method. In particular, the severe degradations of the polarization extinction that result from slow and fast polarization fluctuations in the optical signal components during the in-band OSNR measurement are substantially mitigated by rapidly and/or randomly changing the state of polarization prior to conventional polarization control and filtering.

Abstract: A security image is disclosed which is formed from flakes having a first color with flakes having a second different color mixed within a carrier uniformly. The flakes having the second color are magnetically orientable and the flakes having the first color are non-magnetic and do not align or orient in a magnetic field. By exposing at least a single coated region to a magnetic field that is substantially orthogonal to the substrate upon which the coating of flakes is coated, a visible region having the first color is provided as the magnetic flakes are upstanding and the non-magnetic flakes are lying flat upon the substrate. In another region where there is no field applied a visible region having third perceived color different from, however formed from the first color or the second color is seen.

Abstract: An optical device for rearranging wavelength channels in an optical network is disclosed. The optical device has a wavelength selective coupler having one input port and a plurality of output ports coupled to a plurality of input ports of an optical grating demultiplexor such as an arrayed waveguide grating. The wavelength channels in each of the input ports are dispersed by the demultiplexor and are directed to a plurality of output ports of the optical grating demultiplexor. As a result, at least one wavelength channel at each of the input ports of the optical grating demultiplexor is coupled into a common output port. The optical device is useful in passive optical networks wherein a same demultiplexor is used for simultaneous multiplexing and demultiplexing of wavelength channels.