Patents by Inventor Peter J. Letts
Peter J. Letts has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 9541579Abstract: 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.Type: GrantFiled: September 25, 2012Date of Patent: January 10, 2017Assignee: TEKTRONIX, INC.Inventor: Peter J. Letts
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Publication number: 20160293144Abstract: A method can include generating raster images from digitized signals, each raster image including multiple pixels that each have a count of the number of signals that pass through it, and generating sets of ranges of counts from the totality of counts in a rasterizer image and selected limits on that totality. The method can also include generating mapped images from the raster images and sets of ranges of counts, each mapped image including multiple pixels that each have an output intensity determined by the specific range of counts that contains the corresponding rasterizer image pixel count.Type: ApplicationFiled: March 31, 2015Publication date: October 6, 2016Inventor: Peter J. Letts
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Publication number: 20140088900Abstract: 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.Type: ApplicationFiled: September 25, 2012Publication date: March 27, 2014Applicant: TEKTRONIX, INC.Inventor: Peter J. Letts
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Patent number: 7359810Abstract: 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.Type: GrantFiled: March 18, 2005Date of Patent: April 15, 2008Assignee: Tektronix, Inc.Inventors: Peter J. Letts, Kenneth P. Dobyns, Paul M. Gerlach, Kristie Veith
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Patent number: 7320014Abstract: 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.Type: GrantFiled: December 12, 2003Date of Patent: January 15, 2008Assignee: Tektronix, Inc.Inventor: Peter J. Letts
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Patent number: 6980212Abstract: 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 “tail” 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 “really new” pixels. “Really new” pixels are defined as those that are not adjacent to pixels remaining from earlier acquisitions. Only those waveforms that have more “really new” pixels than a specified fraction of the basic threshold are reported as anomalies.Type: GrantFiled: April 17, 2002Date of Patent: December 27, 2005Assignee: Tektronix, Inc.Inventor: Peter J. Letts
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Patent number: 6928374Abstract: 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.Type: GrantFiled: October 6, 2003Date of Patent: August 9, 2005Assignee: Tektronix, Inc.Inventor: Peter J. Letts
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Patent number: 6778931Abstract: 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.Type: GrantFiled: July 19, 2000Date of Patent: August 17, 2004Assignee: Tektronix, Inc.Inventors: Peter J. Letts, Steven C. Herring
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Publication number: 20040102910Abstract: 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.Type: ApplicationFiled: October 6, 2003Publication date: May 27, 2004Inventor: Peter J. Letts
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Patent number: 6728648Abstract: 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.Type: GrantFiled: June 22, 2000Date of Patent: April 27, 2004Assignee: Tektronix, Inc.Inventor: Peter J. Letts
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Patent number: 6642926Abstract: 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.Type: GrantFiled: June 29, 2000Date of Patent: November 4, 2003Assignee: Tektronix, Inc.Inventor: Peter J. Letts
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Publication number: 20020180737Abstract: 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 “tail” 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 “really new” pixels. “Really new” pixels are defined as those that are not adjacent to pixels remaining from earlier acquisitions.Type: ApplicationFiled: April 17, 2002Publication date: December 5, 2002Inventor: Peter J. Letts
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Patent number: 6297796Abstract: 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.Type: GrantFiled: October 8, 1998Date of Patent: October 2, 2001Assignee: Tektronix, Inc.Inventors: Peter J. Letts, David P. Maguire