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: An apparatus and method for testing an upstream path of a cable network are disclosed. The upstream path is tested by capturing and analyzing upstream data packets generated by a specific terminal device. A test instrument is connected at a node of the cable network. The test instrument establishes a communication session with the headend, informing the headend of an identifier of the device that will generate the test upstream data packet. The test upstream data packet is captured and analyzed at the headend, so that the results of the analysis can be communicated back to the test instrument. To speed up the packet capturing and filtering process, the upstream data packets can be pre-filtered based on packet duration and/or arrival time.

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 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: 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 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: 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 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: The invention relates to a method of performing measurements with a portable meter and reporting measurement data from the portable meter to a central office over a secure channel. The method includes synchronizing the portable meter and the central office though a trusted interface prior to taking measurements at a customer location.

Abstract: Systems and methods for analyzing the performance of a digital network include capturing a stream of digital data, e.g., interne protocol (IP) packets, that represent streaming video, identifying which of the IP packets include bit errors, determining to which of a plurality of pixels the IP packets including bit errors belong and identifying such pixels as corrupted pixels, and illuminating only the corrupted pixels on a display of a tool. Corrupted pixels in different time blocks can be displayed with different colors to gain a better appreciation of the bit error rate over time.

Abstract: The invention relates to a system for end-of-line monitoring of HFC networks by using a main tuner dedicated to receiving measurement requests from a network monitoring server via a DOCSIS downstream channel, and an auxiliary tuner used for the purpose of performing measurements of the downstream channel by analogue and digital measurement circuits. A cable modem is used to transmit measurement results to the server over a DOCSIS upstream channel. The addition of the auxiliary tuner, permits faster measurements to be performed by the EOL monitoring system and reported back to the server, thereby affording real-time remote testing and diagnostics.

Abstract: A home network testing device includes an input port with any one or more of a variety of different connectors for receiving different types of communication cables, e.g. coaxial cable, telephone cable, and electrical cable; and a testing apparatus section with a variety of different testing apparatuses for testing for the presence of different forms of home networks, e.g. MoCA, HomePlug, and HPNA. The present invention uses discrete components to analyze the physical layer in the time domain, looking for a specifically timed RF power pulse that is characteristic of and different in each of the network protocols.

Abstract: The problem is that a measurement of the average signal quality (average modulation error ratio), does not identify poor quality signals that may be originating from an individual cable modem. The device of the present invention displays the modulation error ratio (MER) for each packet received. Since the media access control (MAC) address is associated with a packet received from an individual cable modem, a graph displaying the MER for each packet received is also displaying the MER for signals from the individual cable modems. Thus a technician viewing the display will be able to identify whether a low MER is a result of an impairment in the network or the from an individual cable modem.

Abstract: A method and apparatus for testing a VoIP telephone line are provided, the method including determining which of a plurality of VoIP call control protocols and/or CODECs is compatible with the telephone line, and conducting a series of tests on the telephone line in accordance therewith. The method and apparatus also includes steps and the means to connect to a network and capturing a stream of data therefrom to determine configuration settings of a VoIP telephone connected thereto to facilitate the previous testing.

Abstract: A time division multiplexed measurement technique is used for spectral measurements in active wavelength division multiplexed loaded optical links, and offers instantaneous real-time correlation of performance and spectral parameters of the link, which is important for dynamic characterization of link performance during transient effects or polarization mode dispersion fluctuations.

Abstract: The invention provides a handheld RF meter with an improved isolation from EMI. The meter incorporates an interference barrier comprising a connecting cable and one or more ferrite cores possibly having different impedance characteristics.

Abstract: In conventional testing, the user is using an on-hand computing device to control testing; however, for the present invention the user is at the access point and the computer is remote, e.g. nearby or in the technician's vehicle, and not being used by the user to run the tests. The present invention provides a means to conveniently connect a customer provided network access device, e.g. a USB “dongle” modem, via a wireless link to the remote computer, which is providing the test application. The computer is remote, and the remote module device extends the reach of the commercial dongle modem so it is not necessary to carry the computer to the test access point.

Abstract: The testing device of the present invention includes an RF input for connecting to a subscriber network, which has been disconnected from a communication network, for receiving ingress RF signals leaked into the subscriber network from outside sources. The device includes a signal processor for scanning the RF signals for power levels at a plurality of frequencies, and generating power level signals based at least in part on the power levels. Ideally, the power levels are compared to a threshold power level representing an acceptable amount of ingress, and a pass/fail indicator is displayed based on whether the power levels exceed the threshold power level.

Abstract: A direct way to measure network delay of a packet switched network uses a ping signal injected into the voice stream at a source telephone. The ping signal travels together with the voice stream to a destination telephone. The destination telephone detects the ping signal and returns it to the source telephone through the packet switched network. The source telephone detects the return ping signal sent by the destination telephone and calculates the network delay between the two telephones based on the difference between the time of transmitting the ping signal and the time of detecting the return ping signal. As the ping signal travels in the same path as the voice stream, the network delay between the two telephones is calculated directly and accurately.

Abstract: The present invention relates to a system for calculating a digital quality index (DQI), which provides a rating on a predetermined scale, indicative of the impairments in a received quadrature amplitude modulated (QAM) signal in a CATV cable system. The DQI system utilizes bit error rates prior to and after forward error correction to calculate the DQI value. To increase the calculation rate, the bit error rates can be estimated using voltage errors, signal to noise ratios and/or average corner error metrics.