Tektronix, Inc.

Matthew S Harcourt

Glenn Bateman

Richard I Lane

Ronald J Bremer

Josef L Mader

An optical time domain reflectometer acquires and displays waveform data as a waveform trace on a display device having a viewport defined by a start distance and an end distance using waveform data segments having data points where each waveform segment is acquired using different pulsewidth and sample spacing and different starting distance. A processor sets a horizontal pixel skip value and a horizontal distance skip value for each waveform segment and calculates a horizontal distance per pixel value for the display area as a function of dividing the distance between the viewport start distance and the viewport end distance by the number of horizontal pixels in the display area. Each horizontal pixel is mapped to a distance by setting an initial pixel count to zero and sequentially adding the horizontal pixel skip value to the pervious pixel count and setting an initial horizontal distance value to the start distance of the viewport and sequentially adding the horizontal distance skip value to the previous horizontal distance value. The distance values for the horizontal pixels are correlated to amplitude values of the data points of the waveform segment using an index into the array of waveform data points related to distance. The amplitude values of the acquired data are mapped to appropriate vertical pixels associated with the horizontal pixels to produce a bit representation of the waveform trace, which is displayed on the display device.

Apparatus and method for displaying multiple sample spacing waveform

A system for expanding a waveform in a measurement test instrument has a display area containing a waveform representative of data acquired by a measurement test instrument and an active movable cursor intersecting the waveform. The system has first and second viewports with the first viewport displaying the waveform in the display area and the second viewport displaying a portion of the waveform from the first view port in an expanded form when the second viewport is in the display area. The second viewport has a center point and dimensions defined in the first viewport with the center point being defined by the intersection of the active movable cursor with the waveform and the dimensions being defined with respect with the center point. The second viewport is movable within the first viewport as a function of movement of the cursor. Means are provided for varying the dimensions of the second viewport about the cursor/waveform intersection when the first viewport is in the display area and for further expanding the waveform in a continuous manner about the cursor/waveform intersection when the second viewport is in the display area. Means are provided for replacing the first viewport with the second viewport in the display area.

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Bend, OR, United States of America

Matthew S Harcourt