Abstract: A system for estimating bit error rates (BER) may include using a normalization factor that scales a BER to substantially normalize a Q-scale for a distribution under analysis. A normalization factor may be selected, for example, to provide a best linear fit for both right and left sides of a cumulative distribution function (CDF). In some examples, the normalized Q-scale algorithm may identify means and probabilistic amplitude(s) of Gaussian jitter contributors in the dominant extreme behavior on both sides of the distribution. For such contributors, means may be obtained from intercepts of both sides of the CDF(Qnorm(BER) with the Q(BER)=0 axis, standard deviations (sigmas) may be obtained from reciprocals of slopes of best linear fits, and amplitudes may be obtained directly from the normalization factors. In an illustrative example, a normalized Q-scale algorithm may be used to accurately predict bit error rates for sampled repeating or non-repeating data patterns.

Abstract: A waveform processing system performs operations that may include identifying a location of a specified bit pattern within a coherently sampled repeating pattern input signal. In some examples, multiple periods of a repeating pattern signal are acquired using coherent sampling techniques such as, for example, coherent interleaved sampling (CIS). In such examples, the sampled waveform may be converted to a binary pattern that can be searched to locate a match to a predetermined or user-specified bit pattern. In one illustrative example, the identified location may be used to display the sampled waveform. In another example, the identified location may be used to measure pattern-dependent jitter of the sampled waveform.

Abstract: A method and apparatus for testing a data transfer system. The method comprises the steps of storing a first table, the first table noting at least a time of issuance of at least one command and a time of completion of the command and comparing the time of issuance of the command and the time of completion of the command. A timeout condition is registered if the processor determines that a time longer than a predetermined time elapsed between the time of issuance of the command and the time of completion of the command.

Abstract: A signal processing system compensates for the relative phase difference between multiple frequency bands so that the combination of the bands is constructive throughout a substantial portion of the band overlap or crossover region. In one embodiment, a signal combining system may include a comparator for determining a relative phase difference between the two signals within a predefined crossover region, a phase adjusting element for adjusting a phase of one of the two signals; and a combiner for combining the phase-adjusted signal and the other of the two signals.

Abstract: A method and system are provided for determining a location of a predetermined N bit sequence in a data stream. The method comprises the steps of determining two N bit data words from consecutive bits of the data stream, and providing N, N bit comparators. A first N bits of the two N bit data words is compared with the predetermined N bit data sequence by a first of the N comparators, and a next N bits, starting at a second bit, of the two N bit data words are compared with the predetermined N bit sequence by a second of the N bit comparators. These comparisons are repeated, incrementing the starting bit, until N comparators have been employed and the first through N bits have been employed as the starting bit.

Abstract: A method, apparatus and computer program having instructions for storing information in an oscilloscope is provided. The method comprises the steps of storing a screen display in a predetermined format, storing one or more configuration settings associated with the screen display, and storing in memory channel acquisition data associated with the stored screen display. The screen display may also be annotated, the annotation information being stored as well. The stored screen display, one or more associated configuration settings, and stored channel acquisition data, and annotation data, if applicable, may be loaded into the oscilloscope, thereby placing the oscilloscope in the state it was in when the stored data was originally generated.

Abstract: A method and apparatus for generating one or more transfer functions for converting waveforms. The method comprises the steps of determining a system description, representative of a circuit, comprising a plurality of system components, each system component comprising at least one component characteristic, the system description further comprising at least one measurement node and at least one output node, each of the at least one measurement nodes representative of a waveform digitizing location in the circuit. One or more transfer functions are determined for converting a waveform from one or more of the at least one measurement nodes to a waveform at one or more of the at least one output nodes. The generated transfer functions are then stored in a computer readable medium.

Abstract: A method for improving bandwidth of an oscilloscope involves, in preferred embodiments, the use of frequency up-conversion and down-conversion techniques. In an illustrative embodiment the technique involves separating an input signal into a high frequency content and a low frequency content, down-converting the high frequency content in the analog domain so that it may be processed by the oscilloscope's analog front end, digitizing the low frequency content and the down-converted high frequency content, and forming a digital representation of the received analog signal from the digitized low frequency content and high frequency content.

Abstract: A method and apparatus for correcting for deterministic jitter in a sequential sampling timebase. The value of a fine analog delay is held at a substantially constant nominal rate during a duration of a counting of a digital clock. A time difference between a trigger at which a fine analog delay starts measuring time and the occurrence of a digital pulse of a stable clock used to count a coarse delay is measured. An input waveform is sampled at a sample time having a nominal delay time. After sampling, a desired compensation time is provided for the sample of the input waveform in accordance with combinations of three independent variables defining a calibration table. The waveform is reconstructed by shifting a delay time of a sampled value of the input waveform from its nominal delay time in accordance with a value defined by the calibration table.

Abstract: A probe for probing an electrical device under test is provided. The probe comprises a selectively positionable door defining a recessed compartment and a light source positioned within the recessed compartment. When the door is in a first position, the compartment is closed, and when the door is in a second position, the compartment is opened. When opened, the light source is reflected from a reflective surface of the door to illuminate a device being probed. The door may further comprise a magnifying element to allow for magnification of the area being probed by a user.

Abstract: A high-speed arbitrary waveform generator (AWG) that utilizes multiple digital-to-analog converters (D/A converters) and overcomes bandwidth limitations of individual D/A converters to produce high-speed waveforms.

Abstract: A method and apparatus for probing an electrical signal. The apparatus comprises simplified circuit, comprising an input pin for receiving an input signal having an inductance and parasitic capacitance associated therewith and a first resistor coupled between the input pin and an output. A first capacitor is coupled between the first resistor and the output, and a ground. A second capacitor and an associated inductance in series are coupled between the junction of the first resistor and first capacitor and a parallel circuit arrangement. The parallel circuit comprises a second resistor and second associated inductance coupled in parallel between the first inductor and ground.

Abstract: A waveform processing system, and associated methods and apparatus, may include a common mode feedback compensation circuit to adjust a voltage supplied to a differential circuit so as to substantially reduce or eliminate signal distortion associated with thermal tails. In an illustrative example, a feedback circuit may control a supply voltage to maintain a common mode voltage at the collectors of the input transistors of a differential amplifier. For example, the feedback may compensate for component tolerances and/or temperature changes that may cause the cause the input transistors to operate away from a nominal constant power operating point. In some embodiments, the differential circuit and common mode feedback compensation circuit may be configured to substantially reduce thermal tail effects by controlling the supply voltage to maintain a substantially constant power condition for the input transistors.

Abstract: A method and apparatus for generating a statistic based upon a persistence data is provided. The method comprises the steps of defining a plurality of slices of data comprising a persistence data and generating a histogram of the data within each of the plurality of slices. A parameter is measured for each of the generated histograms, and the measured parameters are plotted corresponding to each of the generated histograms.

Abstract: A waveform processing system may include a compensation circuit to adjust a voltage supplied to an output stage, wherein a supplied voltage is controlled to substantially maintain constant power dissipation in the output stage, and wherein the compensation circuit is configurable independently from the amplification stage. In an illustrative embodiment, a control circuit may be independently configurable with respect to an amplifier that generates a signal for the output stage, and the control circuit may bias a compensation circuit that provides thermal tail compensation for an output stage transistor. In some embodiments, the bias may operate the compensation circuit (i) to maintain a substantially constant power condition in the output stage transistor to substantially reduce thermal tail effects, and (ii) to maintain the output stage transistor in an unsaturated operating condition.

Abstract: Methods for processing waveforms may include decimating an over-sampled waveform by identifying samples for which the sample's position within a data period indicates that is closest to a selected time within a data period. In some example applications, the selected time may be determined as a preferred time to sample the waveform within a data period. In an illustrative example, a sequence of samples representing an over-sampled waveform may be reduced by identifying a sample in each data period that is closest in time to the selected time. In another illustrative example, a sample within each data period may be identified if it falls within a range that is a function of the selected time within the data period and an integral ratio of a sample period to the data period. The identified samples may be used to reconstruct the original waveform with fewer samples than the over-sampled waveform.

Abstract: A system and method for compensation of deterministic jitter in measurements made when utilizing a plurality of time interleaved analog-to-digital converters (ADCs). The system includes edge timing measurement error information for each of the plurality of time interleaved ADCs and a processing element for converting a measured edge time of one or more edges of a waveform into a corrected edge time. The processing element determines the corrected edge time by subtracting the edge timing measurement error corresponding to one or more of the time interleaved ADCs.

Abstract: An artifact signal correction system may include a mixing component to generate a waveform corresponding to an artifact such as an error tone, whereupon that waveform may be combined with the input waveform to substantially eliminate the artifact. In preferred embodiments, a method and apparatus for reducing spurious tones in systems of mismatched interleaved digitizers due to interleave error is provided. In various embodiments the method may include reversing the frequency content of an input signal, converting the reversed signal into interleave artifact content, delaying the input signal along a parallel path, and then subtracting the interleave content from the delayed input signal.