Abstract: A wide bandwidth attenuator input circuit for a measurement probe has a Z0 attenuator circuit coupled in series with a compensated RC attenuator circuit. The series attenuator elements of the Z0 and the compensated RC attenuator circuits are coupled via a controlled impedance transmission line to the shunt attenuator elements of the Z0 and the compensated RC attenuator circuits. The shunt element of the Z0 attenuator element terminates the transmission line in its characteristic impedance. The junction of the series and shunt attenuator elements are coupled to the input of a buffer amplifier. At low and intermediate frequencies, the compensated RC attenuator circuit attenuates an input signal while at high frequencies, the compensated RC attenuator circuit acts as a short and the Z0 attenuator circuits attenuates the input signal.

Abstract: A handle for an electronic instrument housing includes an elongated grip portion. The grip portion includes two elongated elements each having opposed ends. The elements are connected to each other to form an elongated chamber. An elastomeric layer encompasses an intermediate portion of the grip portion, and the grip portion has a vent aperture communicating with the chamber. The vent aperture may be beyond the elastomeric layer, at one or both ends. One of the elongated elements may form a channel with tapered edge surfaces receiving the other element, so that pressure of elastomeric molding tends to wedge the parts together to form a seal against incursion of the elastomer.

Abstract: A system, method and apparatus for triggering a plurality of test and measurement instruments in a substantially simultaneous manner logically combines a trigger enable signal provided by each of a plurality of signal processing devices to produce a combined trigger signal. The combined trigger signal then triggers each of the plurality of signal Processing devices.

Abstract: A method and apparatus are provided to measure spatial distortion. Measure and remove borders; and rescale the active test image, the active reference image, or both, such that they are the same size. A representative line is obtained, or selected, from each image providing a reference representative line (ReferenceRL) and a test representative line (TestRL). A local Pearson' cross-correlation coefficient (LPCCC) image is created from both the ReferenceRL and the TestRL at different horizontal shifts. The highest average intensity line across the LPCCC image is found as the coordinates of the corresponding Hough Transform image pixel with maximum intensity is determined. The Hough Transform Theta and R are converted to spatial scale and offset. The crude and refined offsets and scale values are combined to produce total horizontal and vertical scale offset values. These spatial measurements can then be provided.

Abstract: A method of displaying protocol-specific data includes receiving data, extracting protocol-specific information from the data, converting protocol-specific information into a symbolic representation, and presenting the symbolic representation. A dimension of symbols of the symbolic representation differentiates protocol layers. A test and measurement instrument for displaying data includes an acquisition system configured to receive an input signal, a processor coupled to the acquisition system and configured to generate a symbolic representation of protocol-specific information within the input signal, and a user interface coupled to the processor and configured to present the symbolic representation. A dimension of symbols of the symbolic representation differentiates protocol layers.

Abstract: A test and measurement instrument for displaying data including an acquisition system configured to receive an input signal, a processor coupled to the acquisition system and configured to generate a schematic from protocol-specific information within the input signal, and a display coupled to the processor and configured to display the schematic.

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 method and apparatus for determining the period Tp of a signal representing a digitally modulated waveform using NRZ coding with a discrete/integer number of a clock periods between signal transitions, where a periodic sequence of logic “1s” and logic “0s” is transmitted. The method samples an input periodic signal, constructs an estimate of the autocorrelation sequence rk of the sequence of samples, constructs a sequence of peaks pk, and computes the period Tp to be the time between the first pk sample (k=0), and the time location of the maximum value of pk based on the known Ts spacing of the pk sequence samples.

Abstract: A circuit element has a substrate layer with first and second faces. A conductive first layer overlays the first surface, and a conductive second layer overlays the second surface. The first layer defines a pattern with a trimmable portion. The second layer defines a pattern having a first conductive element registered with at least a portion of the trimmable portion, and a second conductive element electrically isolated from first element and encompassing the first element. The second element may be a ground plane that has an aperture surrounding the first component, which serves as a shield to prevent damage to any elements beyond the second layer.

Abstract: A transition-density based data timing measurement method uses an estimated transition density (TD) value for an acquired data signal together with edge crossing times to estimate a data period for the acquired data signal. The estimated data period is used for symbol classification to determine a number of bits between adjacent edge crossings, which results are used to adjust the TD value. The adjusted TD value is then used to re-compute the data period.

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: Apparatus according to the subject invention includes two independent acquisition systems, wherein one of the two independent acquisition systems acquires the acquisition clock of the other acquisition system along with a signal from a known acquisition reference point. In general, the first independent acquisition system is a logic analyzer, and the second independent acquisition system can be an ILA, a second logic analyzer, an oscilloscope, or other sampling device.

Abstract: A test and measurement Instrument samples an input digital logic signal to produce logic samples, compresses the logic samples into compression codes, and stores the compression codes into acquisition memory. Compression includes parsing the logic samples into groups and assigning compression codes to those groups, and is performed so as not to lose information about the input digital logic signal's activity. The instrument converts the stored compression codes into a waveform image in display memory and displays the stored waveform image on a display device.

Abstract: A signal acquisition probe has a double cushioned spring loaded probing tip assembly disposed in a housing. A first compressive element produces a first pre-loaded compressive force and an increasing compressive force on the probing tip assembly and a second compressive element produces a second pre-loaded compressive force and an increasing compressive force on the probing tip assembly subsequent to the first increasing compressive force. First and second double cushioned spring loaded probing tip assemblies may be disposed in a housing to produce a differential signal acquisition probe.

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 input by-pass circuit for a current probe has first and second switches coupled between current probe inputs and current sensing circuit inputs. A switch control is coupled to the switching circuit for selectively coupling and decoupling the current probe inputs to the current sensing circuit such that the current signal continuously flows in the device under test.