156 Keysight InfiniiVision 2000 X-Series Oscilloscopes User's Guide12 Acquisition ControlWhen you press [Single], the display is cleared, the trigger mode is temporarilyset to Normal (to keep the oscilloscope from auto-triggering immediately), thetrigger circuitry is armed, the [Single] key is illuminated, and the oscilloscopewaits until a trigger condition occurs before it displays a waveform.When the oscilloscope triggers, the single acquisition is displayed and theoscilloscope is stopped (the [Run/Stop] key is illuminated in red). Press [Single]again to acquire another waveform.If the oscilloscope doesn't trigger, you can press the [Force Trigger] key to triggeron anything and make a single acquisition.To display the results of multiple acquisitions, use persistence. See “To set orclear persistence" on page 115.Single vs. Runningand Record LengthThe maximum data record length is greater for a single acquisition than when theoscilloscope is running (or when the oscilloscope is stopped after running):• Single — Single acquisitions always use the maximum memory available — atleast twice as much memory as acquisitions captured when running — and theoscilloscope stores at least twice as many samples. At slower time/div settings,because there is more memory available for a single acquisition, the acquisitionhas a higher effective sample rate.• Running — When running (versus taking a single acquisition), the memory isdivided in half. This lets the acquisition system acquire one record whileprocessing the previous acquisition, dramatically improving the number ofwaveforms per second processed by the oscilloscope. When running, a highwaveform update rate provides the best representation of your input signal.To acquire data with the longest possible record length, press the [Single] key.For more information on settings that affect record length, see “LengthControl" on page 233.Overview of SamplingTo understand the oscilloscope's sampling and acquisition modes, it is helpful tounderstand sampling theory, aliasing, oscilloscope bandwidth and sample rate,oscilloscope rise time, oscilloscope bandwidth required, and how memory depthaffects sample rate.
