The present invention relates to manipulation of waveforms on a display, and more particularly to a simple, integrated control for zoom and pan functions for instruments having a very long data record.
The notion of “zoom” for waveform displays on test and measurement instruments, such as oscilloscopes, has been around a long time. Tektronix, Inc., an Oregon corporation headquartered in Beaverton, Oreg., has oscilloscopes with two separate controls for zoom—one for zoom position and another for zoom factor. An “auto-scroll” feature also exists on high performance oscilloscopes. With the auto-scroll feature a user has the ability to adjust the speed and direction of scrolling or panning.
Introducing a very long data record, such as up to 25 megasamples, into a value oscilloscope allows a zoom factor of 25,000× magnification without interpolation assuming a display width of 1000 pixels. At these large magnification factors zoom navigation either becomes too slow to make large jumps in location within the very long data record, or it becomes too fast to make fine adjustments. To counter this problem the TDS3000 digital storage oscilloscope, manufactured by Tektronix, Inc., uses knob acceleration and also moves a zoom box faster across a display of the very long data record if the zoom magnification factor is small. If the user is closely zoomed in (20×), to make a large jump to another location within the very long data record the user zooms out (2×), adjusts the position of the zoom box on the very long data record, and then zooms back in (20×). This process is not very intuitive and also involves intermediate steps. While a jog/shuttle knob design is commonplace, it has not been used to control a zoom box on a display.
Also in using the oscilloscope's zoom feature the user wants as much time as possible spent in looking at the zoomed waveform on the display represented by the very long data record, not in finding controls to control the zoom. What is desired is a zoom control that is both intuitive and operated by feel alone.