Tektronix, Inc.

Paul M Gerlach

Kenneth P Dobyns

Steven K Sullivan

Kristie L Veith

Jeff W Yost

Samuel J Peters, Ii

Kevin Thomas Ivers

Eric P Etheridge

James L Tallman

Gregory A Martin

Peter J Letts

Terrance R Beale

Robert C Proebstel

George S Walker

Forrest A Edwards

David P Maguire

Daniel E Taylor

Stony D Yakovac

Donovan E Hammer

Jing-Fan Zhang

A waveform display apparatus and method displays one or more waveforms of a signal under test at high throughput while acquiring digital data of the signal under test in a large acquisition memory. A user sets a time interval of user's interest when viewing a signal under test and sets trigger criteria through a user interface. An ADC converts the signal under test into digital data that is stored in a large acquisition memory. A trigger unit detects and produces trigger events, based on a trigger, as trigger event information during one acquisition process. A trigger event eliminator may discard some of the trigger events based on pre-trigger and post-conditions set through the interface by a user. The trigger events are recorded in a trigger list as the trigger event information. A control unit locates the digital data in the acquisition memory corresponding to the trigger events in the trigger list and displays a waveform associated with the trigger event for the time interval on a display device.

High waveform throughput with a large acquisition memory

An apparatus for measuring a parameter of a digitized signal including a digitizer to digitize an input signal into a digitized signal, a rasterizer to generate a raster image from the digitized input signal, a processor to receive the raster image, and a control interface to receive an input control signal indicating a request for a measurement. The rasterizer is responsive to the control signal to generate the raster image from the digitized input signal, and the processor is responsive to the control signal to generate a histogram from the raster image.

Apparatus and method for improved measurement speed in test and measurement instruments

A waveform compression and display technique saves both a peak detected version (background version) and a decimated/lowpass filtered version (foreground version) of a sampled electrical signal. The two versions are displayed simultaneously overlaid together in a contrasting manner so as not to obscure information contained in either of them. The lowpass filtered version uses a series of simple lowpass filters with decimation to produce a single data stream from a plurality of data streams derived from the sampled electrical signal. The single data stream may then be subjected to additional filtering, such as a cascaded integrator-comb filter, to obtain a desired frequency bandwidth. When displayed, the peak detect pixels adjacent the decimated/lowpass filtered pixels may be adjusted in intensity so that the low frequency information of the lowpass filtered waveform is not lost, while the peak detect pixels further from the lowpass filtered pixels are intensified to highlight the high frequency information. Alternatively the background version intensity may be controlled by a user control over a first range from zero to a predetermined maximum, and the foreground version may be controlled over a second range from a default intensity to a maximum, saturated intensity.

Waveform compression and display

A self-adjusting hold-off trigger circuit and method detects a threshold crossing between consecutive samples of a digitized input signal as edge events, identifies the crossing as a qualified trigger event if the crossing is in a desired direction based upon trigger criteria, and provides a trigger output when the qualified trigger event occurs greater than an approximate average or peak time after a preceding edge event.

Self-adjusting hold-off trigger

An apparatus for displaying a digitized waveform includes an overview display configured to display a digitized waveform scrolling across the overview display, a zoom display configured to display a portion of the digitized waveform, and a control unit configured to cause the portion of the digitized waveform displayed in the zoom display to track the displayed portion of the digitized waveform in response to a track signal.

Method and apparatus for digitized waveform display

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

A method and apparatus in which a plurality of demux processors propagates respective received sample streams to adjacent demux processors via an inter-demux bus; and wherein a final one of the plurality of demux processors propagates all of the respective received sample streams toward a next processing element such as a multi-drop bus (MDB) or system processor within a data acquisition device.

Inter-demux communication through a point to point interface

A multiple channel signal acquisition device wherein each channel performs a respective rasterization process to provide respective waveform imagery, the respective waveform imagery having a display parameter reduced at a decay rate, the respective waveform imagery being propagated towards an adjacent input channel for combination, the combined image being propagated towards each remaining channel for combination into a final waveform image for display.

Architecture for improved display performance in a signal acquisition and display device

A system is disclosed for equalizing the distribution of pixel intensities in an image displayed by an oscilloscope. In a primarily software implementation, the maximum pixel intensity (I) present in the rasterized input image, the maximum available display intensity (P) and the desired image resolution (R) are the input variables which permit the calculation of thresholds or bins to which each pixel is assigned. By iteratively performing the analysis of existing pixel intensities and bin thresholds, the number of pixels in each bin may be optimized to form an equalized histogram. Another implementation of the histogram equalization system utilizes software to optimize a hardware-based histogram collector.

Histogram data collector for applying progressively adjusted histogram equalization to an oscilloscope image

A method and apparatus for rasterizing a digital sample stream by producing histograms for each of a plurality of time slices forming a display frame. Time slice histograms for at least one display frame are stored in a circular memory buffer and provided to a display raster for display. The first time slice displayed optionally comprises that time slice temporally associated with a trigger condition.

Architecture providing increased information display for long acquisitions or constrained memory bandwidth

A signal acquisition instrument acquires a succession of waveform records and sequentially transfers the waveform records to a rasterizer for rasterizing the waveform records to generate respective rasterized records each composed of a set of vectors, but inhibits transfer of a current waveform record to the rasterizer until a previous waveform record has been rasterized. The maximum number of dots (M) in each vector is made as large as possible provided that the rasterizer does not complete rasterization of the previous waveform record after acquisition of the current waveform record is complete.

Method of controlling a sparse vector rasterizer

Unusual waveforms are defined in terms of how many &ldquo;new&rdquo; pixels are affected by the process of rasterizing them. New pixels can be those not yet affected by the rasterization of any waveform in the current set of acquisitions, or to be those that have had higher values in their raster memory location but have now been decayed to below a defined value. Once detected, such waveforms can be re-rasterized with extra intensity or into a different color by using a reserved range of values of those storable in the raster memory. Alternatively, the special region of values can be used as a counter/timer to maintain the pixels associated with unusual waveforms at a brightest intensity value, or in the color equivalent, for an extended period of time. User input can be used to affect the definition of &ldquo;new&rdquo; pixels and to control the special persistence given to unusual waveforms. Unusual waveforms can also be saved in long term memory. Multiple decay functions and regions of values in the raster memory locations can be used as described above, or to produce a fast rate of decay in a bright visible region and a user adjustable slower rate of decay in a dimmer region, thus making recently acquired waveforms look bright and &ldquo;lively&rdquo;, while older waveforms appear to be relatively gray and stable. The same techniques can be employed when color is used either along with or as a substitute for intensity variations.

Multi-function digital persistence decay

A raster scan digital signal acquisition and waveform display instrument displays a dot representing a signal event with a color parameter in accordance with the value of a corresponding data word stored in a raster scan memory. A user interface control element supplies a single color parameter control value from which multiple independent control values for influencing the values of the data words stored in the raster scan memory in response to the single color parameter control value are generated.

Method of controlling brightness and contrast in a raster scan digital oscilloscope

A luminance component extractor coupled to a source of a composite video signal including a luminance component. A sampler, coupled to the video signal source, produces samples representing a frame the video signal. A memory maintains minimum and maximum values of each sample in the frame of the video signal. A non-linear low pass filter, responsive to the minimum and maximum values, generates samples representing the luminance component.

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Beaverton, OR, United States of America

Paul M Gerlach