|Figure 1: Initial setup of WaveSurfer 3000 with a|
2-MHz pulse waveform fed into Channel 1
All that memory comes into play when one invokes History Mode, a debug and analysis tool found in many Teledyne LeCroy oscilloscopes. History Mode lets users scroll back in time to isolate anomalies or other waveform events. Then, they can be measured with parameters or cursors to quickly turn up the sources of signal problems.
Often, when we view waveforms on an oscilloscope's display, unexpected events may occur and we'll want to stop the trigger and view these interesting little behaviors. The great thing about History Mode is that it automatically stops the trigger and displays a list of previously captured waveforms. This shortens the amount of time it takes to identify problems, enabling us to view, quantify, and analyze those anomalies in our signal.
Here's an example, in which we fed a 2-MHz pulse into Channel 1 of a WaveSurfer 3000 (Figure 1). The best way to access History Mode is directly from the front panel; it's also available in the Timebase drop-down menu. Pressing the History button stops the trigger and displays a list of previously captured waveforms alongside the waveform grid. Here's how the History Mode dialog box looks along with the waveform list (Figure 2).
|Figure 2: Invoking History Mode with the front-panel button|
opens the related dialog box at bottom.
The Waveform History Navigation controls in the History Mode dialog give users a flexible means of traveling backward and forward through all of the acquisitions stored in memory. The controls offer slow/fast scrolling, single stepping, and a second scroll bar (Figure 2, again).
The top row of controls regulates scrolling with the two outer buttons starting a fast scroll and the two inner buttons a slower rate of scrolling. On the bottom row, the two outer buttons take the user to the oldest and newest acquisitions while the inner pair step through one at a time. You can tap the index box to directly enter a specific acquisition. The Relative Times check box toggles between the table displaying the absolute times of acquisitions and the relative time from the last acquisition.
|Figure 3: Users can perform measurements and/or math|
operations on any History Mode acquisition.
History Mode, then, is a great debug and analysis tool, automatically saving all acquisitions and giving users a convenient means of navigating amongst them with a tabular list.