Abstract: A circuit and method of qualified anomaly detection provides detection and triggering on specific analog anomalies and/or digital data within a qualified area of a serial data stream. A start pattern within the serial data stream, such as a packet header, is detected to generate an enable signal. A stop event, such as a packet trailer, a specified digital event, a time interval or the like, is identified to generate a disable signal. The enable and disable signals are combined to produce a qualification signal that allows a trigger circuit to trigger on a specified anomaly within the portion of the serial data stream defined by the qualification signal.

Abstract: A system for providing an easily usable composite legality and component gamut display translates a video input signal into a plurality of component and composite format signals. A user selects from the plurality of component and composite format signals a pair of signals for input to the y-axis and x-axis of a rectangular plot. The resulting rectangular plot includes every pixel within a video frame of the video input signal and, together with prescribed limits, is displayed to provide a visual indication of composite legality and/or component gamut.

Abstract: An RF/IF signature trigger for acquiring received RF signal data is generated by correlating the received RF signal data in the form of a time domain RF/IF signal, a detected RF/IF signal and/or a frequency domain RF/IF signal with a reference signal defined by a signal signature record representing desired/undesired RF/IF signal patterns, detected RF pulse shapes, special RF markers used specifically for triggering signal acquisitions, particular signal patterns of interest and the like. The resulting correlation factor continuously calculated in real time is compared with a variable correlation threshold such that when the correlation factor reaches the variable correlation threshold, either positive or negative, the RF/IF signature trigger is generated to acquire the received RF signal data for analysis.

Abstract: A decoding device for analyzing communication protocols has a generic decoder into which at least one protocol description of a communication protocol is loaded, the at least one protocol description being capable of being interpreted by the generic decoder. The decoding device also has a specific decoder designed for a certain protocol description. The generic and specific decoders are reversibly connected.

Abstract: Carrier frequency detection for an N-ary modulated signal is achieved by digitizing the N-ary modulated signal, frequency shifting the digitized N-ary modulated signal to prevent aliasing, raising the frequency-shifted signal to the Nth power, transforming the raised signal to frequency domain data and determining an initial maximum frequency peak, iteratively fine shifting the frequency of the N-ary modulated signal around the initial maximum frequency peak and repeating the raising, transforming and determining steps to obtain a plurality of maximum frequency peaks, and calculating the carrier frequency from the maximum frequency peaks and the total related frequency shift.

Abstract: A wideband signal analyzer has a plurality of frequency conversion paths for simultaneously processing different contiguous frequency bands of an input signal. Each frequency conversion path provides time domain data for input to a digital signal processor. The digital signal processor interpolates each group of time domain data to produce interpolated time domain data having a number of data points that satisfies a Nyquist condition for a combined bandwidth of the frequency conversion paths. A calibration signal set to a border frequency between a pair of frequency conversion channels is used to calibrate the gains and phase differences between the frequency conversion paths so that the digital signal processor identifies corresponding time domain data between the interpolated time domain data groups. A suite of frequency domain data is calculated by the digital signal processor from the interpolated time domain data groups and stored for subsequent display.

Abstract: K2T measurement of video signals, regardless of video format, is determined by generating a graticule using an algorithm having a single variable that is a function of the video format for the particular video signal. The graticule is set to a normalized value of one for a range of +/?T, where T is a function of the video format. The graticule is set to a normalized value over a range of +/?(1.5T to flatBreak) according to a human vision masking model algorithm expressed as K+C/t, where K is a constant K factor, t is a function of T, and C is the single variable that is a function of the video format. The normalized value of the graticule beyond a point designated by flatBreak is a constant=K. Finally a linear curve fit between one and K+C/t over the range of +/?(T to 1.5T) sets the remaining values for the graticule.

Abstract: An up-sampled half band reconstruction filter has a seagull architecture in the form of a pair of parallel infinite impulse response (IIR) filters, one receiving as an input an input signal delayed by one sample time and the other receiving as an input a reverse version of the input signal delayed by one sample time. The outputs from the pair of parallel IIR filters are combined with the input signal to produce a reconstruction filter output in response to the input signal.

Abstract: A user interface for an event monitor that monitors a data stream receives an event message having at least one level of categorization, adds the event message to a log file, produces an alert status corresponding to a value of a component of the at least one level of categorization, selects the component of the at least one level of categorization, creates a filter according to filter criteria corresponding to the selected component of the at least one level of categorization, filters the log file to produce a filtered log file, and outputs the filtered log file containing event messages corresponding to the selected component of the at least one level of categorization.

Abstract: A robust phase-lock detector for a phase-locked loop examines both the sum frequency and baseband components of an error signal from the phase-locked loop to determine that both a reference signal and an output signal for the phase-locked loop are present and that the reference and output signals have a desired phase relationship. An IF detector selects the sum frequency component, which is the sum of the reference frequency and a subdivided frequency from the output signal, and detects its presence. A baseband detector selects the baseband component and detects whether the baseband component is approximately zero volts. The outputs from the IF detector and the baseband detector are combined to produce a lock signal, indicating that the phase-locked loop is locked, i.e., the reference and output signals are present and have the desired phase relationship with respect to each other.

Abstract: A fault severity check and source identification method for a frequency domain instrument accesses acquired reflection data for a transmission line under test. From the acquired data reflection surfaces are isolated as a function of distance. Each reflection surface is examined to produce a frequency response profile and a worst-case reflection response to determine fault severity. The frequency response profile may also be correlated in a pattern recognition algorithm with known reference source profiles to determine the source identification for the fault.

Abstract: The present invention relates to a process for learning a basic finite automaton of a protocol implementation, which process is characterized by the following steps: a) categorizing the times (1, 2, 3) within an example communication into equivalence classes and b) using said equivalence classes as states of the learned automaton. The invention further relates to a process for learning arithmetic classification rules for feature vectors from a training set of positive examples, which process is characterized by the following steps: a) forming derived features (y?v; x?z), based on statistical measures, in the form of arithmetic terms; b) formulating logic conditions (x=w+1, y=v+1, z=x) on the numerical values of the features from the training set or the derived features.

Abstract: A method of characterizing a newly acquired waveform with respect to previously acquired waveforms during monitoring of a generally repetitive signal, where the previously acquired waveforms have been rasterized into a two-dimensional array of memory locations, reads history values for those memory locations associated with an active portion of the newly acquired waveform, compares the history values with history value ranges, increments a count for one of a plurality of recent pixel counters corresponding to the history value ranges, each counter having a different history value range, and modifies the history values in the memory locations. From the counts accumulated for each of the history value ranges the variability of the newly acquired waveform from the generally repetitive signal is determined.

Abstract: An improved digital trigger circuit has a plurality of data samples extracted from an input electrical signal for each sample clock cycle. The plurality of data samples are compared in parallel with a high threshold level and a low threshold level which provides hysteresis for noise rejection. Also the plurality of data samples are used to determine sub-sample trigger positioning. The comparison outputs are input to a digital trigger logic circuit for identifying a selected trigger event and generating a trigger for the acquisition of data from the input electrical signal for analysis and display. The digital trigger logic provides edge event triggering, pulse width triggering and transition time triggering, among others.

Abstract: A gamut error false color display uses false coloring on a monochrome image of a video picture being tested. Composite and component gamut error signals are extracted from an input video signal representing the video picture being tested. Such error signals may represent gamut error states corresponding to near out-of-gamut, out-of-gamut high, near out-of-gamut low, out-of-gamut low, etc. A false color display generator has the gamut error signals and a luminance component of the input video signal as inputs and outputs the gamut false color display as the monochrome image with different colors for those pixels in the monochrome image that correspond to the gamut error signals when a gamut error is indicated. Each display component may be tested for gamut errors as well as the video picture as a whole (component or composite). Also either fixed or variable persistence may be used to identify gamut errors over several video pictures in the input video signal.

Abstract: A tracking generator for an RF measurement instrument having a receiver and a controller includes a vector modulator internal to the tracking generator. The internal vector modulator modulates complex baseband signals based on data from the controller to produce a vector modulation signal. The vector modulation signal is used to modulate a local oscillator frequency from the receiver in an output mixing stage to produce a test signal having an output frequency that matches a measurement frequency to which the receiver is tuned. By controlling the complex baseband data from the controller, an adaptive filter at the output of a DAC that produces an analog signal from the digitally modulated complex baseband data, an internal independent oscillator for the vector modulator, or a large offset phase-locked loop, an offset from the measurement frequency may be generated for the output frequency.

Abstract: A user interface for a traffic load simulator for a telecommunication system divides call traffic into sub-groups of call traffic that have a common characteristic. Such sub-groups may include rush hour callers, lunch time callers, teenagers, internet surfers, business customers and other background callers that do not fit into any one sub-group. Each sub-group is represented as a timeline on a display where the traffic for the sub-group is simulated with ramp up and decline rates corresponding to the rate at which calls are added to the system or disconnected from the system and steady state volume between the ramp up and decline, all as a function of time-of-day. The timelines may be manipulated by graphically changing the rates, steady state volume and time-of-day for the events. In this manner realistic traffic loads on the system may be simulated to determine times and nodes when and where the system may be overwhelmed.

Abstract: A frequency down converter that maintains accuracy even if the frequency pass band is wide uses a reference frequency band within the frequency pass band, the reference frequency band being resistant to degradation by aging or temperature variation. The ideal characteristics of the reference frequency band are previously stored. The frequency down converter has a calibration signal source that inputs a calibration signal to the frequency down converter to measure the characteristics of the reference frequency band and to store differences from the ideal characteristics. The calibration signal is input to obtain the characteristic data of other frequency bands within the frequency pass band, and the characteristic data are revised by the above differences. Then compensation coefficients to compensate the revised characteristic data into the ideal characteristics are calculated.

Abstract: A method of non-invasive estimation of round trip time (RTT) between a sender and receiver in a packet oriented acknowledgment based transmission system uses a probe to monitor signals transmitted between the sender and receiver at any point in the transmission system. For a presetable number of acknowledgments in a sequence of acknowledgments received by the probe within a time interval, the time stamps of the acknowledgments are compared (i) with the timestamps of the packets received before the acknowledgments to determine an estimated value for the round trip time between the probe and receiver, and (ii) with the timestamps of the packets received after the acknowledgments to determine an estimated value for the round trip time between the probe and sender. Also sequence numbers of the same group of acknowledgments are compared with the packets encountered to perform a distance function along the sequence numbers themselves.

Abstract: Image alias rejection when converting a high resolution rasterized waveform to a lower resolution rasterized waveform for display uses a statistical filter. The statistical filter provides a shaped probability density function either by combining the outputs of multiple random number generators, such as linear feedback shift registers, or by using a corresponding look-up table to produce a dither signal. The statistical filter may be applied to one or both of the dimensional values for each data point of the high resolution rasterized waveform by combining the dimensional values with the dither signal. The resulting filtered dimensional values may then be subsampled, such as by truncation, to produce values for a lower resolution rasterized waveform display.