Abstract: An instrument for depicting change in the value of a first variable as a function of a second variable comprises a display device for displaying a set of n measured values distributed along a display axis, and a sampler for acquiring a set of N (greater than n) samples of the first variable and storing values of those N samples in ordered fashion relative to a first storage domain that maps to the second variable. A set of n display samples is selected from the set of N stored samples and the values of that set of n display samples are provided to the display device. When the set of n display samples is a set of samples that are at a predetermined spacing in the first storage domain and/or occupy a selected interval of the first storage domain, a set of N1 (greater than n) samples of the first variable are acquired and their values are stored in ordered fashion relative to a second storage domain that maps to the interval of the first storage domain.

Abstract: 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.