Tektronix, Inc.

Peter J Letts

Kenneth P Dobyns

Paul M Gerlach

Kristie L Veith

Steven C Herring

David P Maguire

Method and devices are described for visually detecting anomalies in non-repetitive signals. One device may take the form of an oscilloscope capable of displaying segments of a complete waveform record that includes non-periodic triggering events. The segments may be displayed vertically and horizontally offset from one another to aid in the visual detection of anomalies within the record. Decayed or aged segments of a waveform may also be simultaneously displayed.

Methods and systems for generating displays of waveforms

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.

Characterizing newly acquired waveforms for identification of waveform anomalies

Method and apparatus for correlating data records acquired in a signal acquisition device includes the steps of extracting an area of interest from the data record displayed on said signal acquisition device, normalizing the area of interest, creating a filter based upon normalized values of the area of interest and passing the data record through said filter to obtain a correlation curve. Normalization of the area of interest includes obtaining a plurality of points defining the area of interest, calculating the mean of the said plurality of points and subtracting said mean from each of the said plurality of points. Creating the filter includes using the normalized values of the area of interest as coefficients for the filter.

Method and apparatus for identifying similar events in long data records

Apparatus in accordance with the subject invention maintains an exponentially decayed histogram of the counts of new pixels for each active channel, together with a running count of time and number of acquisitions. At regular intervals determined by a maximum time or by a minimum number of acquisitions it computes a new threshold for each active channel. This threshold will theoretically produce 'N' nominally unusual waveforms per second where N is defined by a user 'sensitivity' control. The raw histogram is smoothed to provide a stable &#x201c;tail&#x201d; of small probabilities. Once a threshold has been determined, subsequent waveforms with more than this number of new pixels are re-examined to determine the number of &#x201c;really new&#x201d; pixels. &#x201c;Really new&#x201d; pixels are defined as those that are not adjacent to pixels remaining from earlier acquisitions. Only those waveforms that have more &#x201c;really new&#x201d; pixels than a specified fraction of the basic threshold are reported as anomalies.

Method and apparatus for computing thresholds for identification of waveform anomalies

Methods for displaying an anomaly in a periodic waveform. Specifically, in one embodiment according to the present invention, a method is provided of (a) setting a pulse start address, (b) setting an initial screen position, (c) displaying a pulse at a time-aligned position, (d) updating the pulse start address in response to a pulse width value, (e) repeating (c) and (d), and (f) interactively adjusting the pulse width value at any time without using a clock recovery procedure.

Methods for displaying jitter and other anomalies in long acquisition data records

In a test and measurement instrument having M signal input channels, individual samples representing a signal from each channel are compared to mask pixels to detect non-compliance with a given specification. Initial mask and waveform positions on a display screen of the oscilloscope are determined by an AUTOSET TO MASK function. Comparison of mask pixels and waveform pixels to detect collision between a waveform pixel and a mask pixel (i.e., a mask violation) is performed substantially in real time, as the pixels are being composited into a raster memory by a rasterizer. Acquisitions are performed simultaneously and repeatedly. Acquired waveforms from all M signal input channels are sequentially compared to the mask and drawn on screen during the following acquisition period. Thus, M waveforms can be tested for compliance with a telecom mask substantially within a single acquisition time period. A system employing a multiplexer can select M channels at a time from a group of N channels to decrease the time required to test all N channels. The intensity of pixels representing samples violating the mask is preferably increased for better visibility against the telecom mask.

Test and measurement instrument having multi-channel telecommunications mask testing capability

Initial mask and waveform positions on a display screen may be determined by an AUTOSET TO MASK function. Upon detection of violations that occur after the AUTOSET TO MASK function is complete, control for further alignment of the waveform under test and the mask is assumed by an AUTOFIT TO MASK function. Comparison of the mask pixels and waveform pixels to detect collision between a waveform pixel and a mask pixel (i.e., a mask violation) is performed substantially in real time, as the pixels are being composited into the raster memory by the rasterizer. In the event of a mask violation, a mask violation signal is generated. In a further embodiment of the invention, in response to the mask violation signal, the AUTOFIT TO MASK function uses display rasterization to automatically redraw the waveform at a new location, until the waveform fits within the mask. In yet another embodiment, in response to the mask violation signal, the AUTOFIT TO MASK function automatically redraws the telecom mask at a new location until the waveform fits within the mask.

Test and measurement instrument having telecommunications mask testing capability with an autofit to mask feature

A telecom mask testing zoom function draws mask. pixels into a raster memory. In this way, the mask is treated as a waveform. Comparison of the mask pixels and waveform pixels to detect collision between a waveform pixel and a mask pixel (i.e., a mask violation) is performed substantially in real time, as the pixels are being composited into the raster memory by the rasterizer. The mask is scalable and repositionable by the rasterizer under control of a controller, because it is treated as a waveform. The mask is lockable to the waveform because both are stored in pixel form in raster memory by the rasterizer under control of the controller.

Test and measurement instrument having telecommunications mask testing capability with a mask zoom feature

An apparatus and method for inverting a color display on a dark background to produce a display on a substantially white background suitable for printing, includes the element of maintaining the same apparent relative intensities in both the LCD display on a dark background and the hardcopy displayed on a light background. The apparatus includes a memory including a first palette for the LCD display, a second palette for the hardcopy display, and a look-up table. A controller accesses the first and second palettes and look-up table for converting display data from LCD data to color-inverted printer data.

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Beaverton, OR, United States of America

Peter J Letts