User manual

WaveSurfer 3000 Oscilloscopes

Sampling Modes

Real Time Sampling Mode

Real Time sampling mode is a series of digitized voltage values sampled on the input signal at a uniform

rate. These samples are displayed as a series of measured data values associated with a single trigger

event. By default, the waveform is horizontally positioned so that the trigger event is time zero on the grid.

The relationship between sample rate, memory, and time can be expressed as:

Capture Interval = 1/Sample Rate X Memory

Capture Interval/10 = Time Per Division

In Real Time sampling mode, the acquisition can be displayed for a specific period of time (or number of

samples) either before or after the trigger event occurs, known as trigger delay. This allows you to isolate

and display a time/event of interest that occurs before or after the trigger event.

l Pre-trigger delay displays the time prior to the trigger event. This can be set from a time well before

the trigger event to the moment the event occurs, up to the oscilloscope's maximum sample record

length. How much actual time this represents depends on your timebase setting. When set to the

maximum allowed pre-trigger delay, the trigger position (and zero point) is off the grid (indicated by the

trigger delay arrow at the lower right corner), and everything you see represents pre-trigger time.

l Post-trigger delay displays time following the trigger event. Post-trigger delay can cover a much

greater lapse of time than pre-trigger delay, up to the equivalent of 10,000 time divisions after the

trigger event occurred. When set to the maximum allowed post-trigger delay, the trigger point may

actually be off the grid far to the left of the time displayed.

Usually, on fast timebase settings, the maximum sample rate is used when in Real Time mode. For slower

timebase settings, the sample rate is decreased so that the maximum number of data samples is

maintained over time.

Sequence Sampling Mode

In Sequence Mode, the complete waveform consists of a number of fixed-size segments (see the instrument

specifications at teledynelecroy.com for the limits). The oscilloscope uses the sequence timebase setting

to determine the capture duration of each segment as 10 x time/div. With this setting, the oscilloscope uses

the desired number of segments, maximum segment length, and total available memory to determine the

actual number of samples or segments, and time or points.

Sequence Mode is ideal when capturing many fast pulses in quick succession or when capturing few events

separated by long time periods. The instrument can capture complicated sequences of events over large

time intervals in fine detail, while ignoring the uninteresting periods between the events. You can also make

time measurements between events on selected segments using the full precision of the acquisition

timebase.