Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: Method and systems are described for estimating signal impairments, in particular jitter that includes uncorrelated, non-periodic signal impairments. One system may take the form of an oscilloscope. The estimates may take the form of a probability density function (PDF) for uncorrelated signal impairments that has been modified to replace low probability regions with a known approximation and an extrapolation of the known approximation.

Abstract: A method of generating a stereoscopic image registration and color balance evaluation display enables a user to align two cameras used to produce a stereoscopic video signal or to analyze a received stereoscopic video signal. Left and right images from the cameras are converted into desired video signal components. Corresponding pixels from the left and right images are compared for each of the video signal components, and plotted as x and y inputs to a Cartesian plot to produce respective two-dimensional (2D) histograms. The multiple 2D histograms are presented as a Quad Diamond display so a user may align the two cameras or analyze the received stereoscopic video signal.

Abstract: System and method for forwarding a ciphering key to a decipher application comprising capturing a first message carrying the ciphering key from a first network interface, identifying a network node associated with the first network interface, identifying a monitor responsible for processing messages captured from interfaces coupled to the network node, and forwarding the ciphering key to the monitor. In an alternative embodiment, the method may further comprise capturing second messages carrying encrypted messages from a second network interface, and deciphering the second messages using the ciphering key. The method may also comprise identifying user equipment associated with the first messages, and selecting a deciphering application running on the monitor using a user equipment identity.

Abstract: A system and method for monitoring IP flows in a network is disclosed. A plurality of monitor probes are coupled to links in the network, the monitor probes capture data packets from the links and determine protocols in OSI Layers 3, 4, and 5/7 of the packets. A user interface receives user inputs selecting the links and protocols for analysis. A display is coupled to the monitor probes and the user interface. The display and user interface receiving a user selection of links for analysis and display a first protocol analysis to the user, the first protocol analysis display comprising a pie chart representing all OSI Layer 3 protocols captured on the selected links, a pie chart representing all OSI Layer 4 protocols captured on the selected links, and a pie chart representing all OSI Layer 5/7 protocols captured on the selected links.

Abstract: System and method for combining call records for different protocols into a single combined call record during a call. An embodiment comprises correlating messages having multiple protocol formats, comprising correlating messages complying with a first protocol into a first call record using a first correlation key, correlating messages complying with a second protocol into a second call record using a second correlation key, detecting a key message complying with the first protocol, the key message having a fetch key parameter associated with messages complying with the second protocol, combining data from the second call record into the first call record to create a combined call record, and creating a pointer linking the second call record to the first call record.

Abstract: A time qualified frequency mask trigger triggers on signals that violate a frequency mask for at least a specified time duration. A frame of digital data representing an input signal is transformed into a frequency spectrum having at least one frequency bin, with each frequency bin having a power amplitude value. A trigger signal is generated when any of the power amplitude values violates an associated reference power level for at least a specified time duration.

Abstract: A method and apparatus for improved video bandwidth resolution in DFT-based spectrum analysis is disclosed. A first embodiment comprises an emulation of a continuous range of video bandwidths in DFT-based spectrum analysis using overlapping resolution bandwidth frames. A second embodiment utilizes frame weighting to reduce the standard deviation in the spectrum of noise signal to emulate a corresponding standard deviation of a specified video bandwidth.

Abstract: A processor performs line-rate filtering using hardware-assisted Patricia trees. A PCAP-style filter is converted into a form that can be inserted into a Patricia tree. The PCAP filter expression is parsed and converted into disjunctive normal form (DNF). Each DNF clause of the filter is inserted into a Patricia tree. The DNF clauses are checked for overlaps and the overlapping clauses are combined when possible.

Abstract: A power trigger is provided having time qualified and sequential event capability. Digital data representing an input signal is converted into a power signal. The power signal is compared to a trigger level. A trigger signal is generated when the power signal violates the trigger level for either at least or less than a specified time duration. Alternatively, the trigger signal may be generated on the occurrence of a sequence of such violations.

Abstract: Embodiments of the present invention provide a variable inter symbol interference generator that generates a data signal having a variable amount of inter symbol interference by passing a data signal through (1) a programmable filter having an adjustable frequency response, and through (2) a fixed filter having a fixed frequency response such as a PCB trace, a length of cable, a discrete filter, or the like. By adjusting the parameters and therefore the insertion gain or loss of the programmable filter, a large range of continuously variable and finely-tunable inter symbol interference amounts can be easily generated.

Abstract: A test and measurement instrument and method for generating IQ-based time domain waveform information and presenting the IQ-based time domain waveform information together with other time domain waveform on a common axis through a user interface. The test and measurement instrument can include, for example, one or more input terminals to receive an electrical signal under test, an analog-to-digital converter (ADC) to digitize the signal under test, a digital downconverter to produce I (in-phase) and Q (quadrature) baseband component information from the digitized signal, a memory configured to store the IQ baseband component information, a user interface, and a controller. The controller can be configured to generate an IQ-based time domain waveform using the IQ baseband component information, and present the IQ-based time domain waveform and a second time domain waveform on a common axis through the user interface.

Abstract: A dF/dT trigger system and method includes instantaneously triggering on a frequency deviation of a data signal, which can be associated with an SSC signal. After receiving a signal at an input terminal of a test and measurement instrument, the signal is low-pass filtered and transmitted to trigger circuitry. When a frequency deviation rate in the filtered signal exceeds or crosses one or more thresholds, a trigger event is produced. Also disclosed is a test and measurement instrument including an input terminal to receive the signal, input circuitry to receive and process the signal, and dF/dT trigger circuitry configured to receive the signal and produce a trigger event when a frequency deviation in the signal exceeds or crosses one or more thresholds.

Abstract: A realtime spectrum trigger system on a realtime oscilloscope considers both the magnitude and phase of an input signal having a periodic component so that successive acquisitions of the input signal are time aligned. A user inputs a frequency, threshold and phase for triggering on the periodic component. Input signal samples are filtered by quadrature filters according to the frequency input to produce quadrature signal components. The square of the magnitude of the input signal is computed from the quadrature signal components, as well as the phase ratio and sign, for comparison with calculated values. When enabled by the magnitude of the input signal, a phase crossing determinator compares the phase ratio and sign with calculated values to determine the phase crossing to generate a trigger, resulting in successive acquisitions of the input signal being in time alignment.

Abstract: Video data packets transmitted through a wireless network are captured by a network monitoring system. Video data sessions are detected from the video data packets. Key parameters are identified within the video data packets, such as video bit rate, resent or failed video packets, and video session duration. A Quality of Experience (QoE) is determined for some or all users associated with the video sessions based upon the key parameters. A header extension is added to the video data packets by a transcoding system. The header extension includes data associated with original and transcoded video data packets. The network monitoring system monitors the header extension and evaluates the effect of video transcoding upon the overall QoE for users. The monitoring system provides feedback to a transcoding policy engine based upon the effect of transcoding upon QoE.

Abstract: A test and measurement instrument including a plurality of channels, each channel configured to receive a corresponding input signal. Each channel includes a comparator configured to compare the input signal to a threshold for the channel; an edge detector configured to detect an edge of an output signal of the comparator; and a threshold controller configured to adjust the threshold for the channel in response to the edge detector.

Abstract: A method is provided to predict the location of attention focus probability trajectories due to distractions in a test video. A peripheral sensitivity probability map is created base upon a nominal measurement map, and an attention probability map, which are both based on a test video input. A focus of attention probability map with distraction is produced based upon the peripheral sensitivity map, the nominal measurement map, the attention probability map and a distractibility control input.