User manual

Acquisition

RIS Sampling Mode

RIS (Random Interleaved Sampling) allows effective sampling rates higher than the maximum single-shot

sampling rate. It is available on timebases ≤ 10 ns/div.

The maximum effective RIS sampling rate is achieved by making multiple single-shot acquisitions at

maximum real-time sample rate. The bins thus acquired are positioned approximately 20 ps (50 GS/s)

apart. The process of acquiring these bins and satisfying the time constraint is a random one. The relative

time between ADC sampling instants and the event trigger provides the necessary variation.

Because the instrument requires multiple triggers to complete an acquisition, RIS is best used on

repetitive waveforms with a stable trigger. The number depends on the sample rate: the higher the sample

rate, the more triggers are required. It then interleaves these segments to provide a waveform covering a

time interval that is a multiple of the maximum single-shot sampling rate. However, the real-time interval

over which the instrument collects the waveform data is much longer, and depends on the trigger rate and

the amount of interleaving required.

Note: RIS is not available when the oscilloscope is using another form of interleaving.

Roll Sampling Mode

Roll mode displays, in real time, incoming points in single-shot acquisitions that appear to "roll"

continuously across the screen from right to left until a trigger event is detected and the acquisition is

complete. The parameters or math functions set on each channel are updated every time the roll mode

buffer is updated as new data becomes available. This resets statistics on every step of Roll mode that is

valid because of new data.

Timebase must be set sufficiently slow to enable Roll mode selection; increase Time/div to 50 ms/div or

more and decrease sample rate to 2.5 MS/s or less to to activate the Roll mode option on the Timebase

dialog. Only Edge trigger is supported for Roll mode acquisitions.

Note: Roll sampling is not available when using digital interleaving. If processing time is greater

than acquisition time, the roll mode buffer is overwritten. The instrument warns, "Channel data is

not continuous in ROLL mode!!!" and rolling starts again.

Sequence Sampling Mode

In Sequence Mode sampling, the completed waveform consists of a number of fixed-size segments. The

instrument uses the Timebase Sequence settings to determine the capture duration of each segment.

The desired number of segments, maximum segment length, and total available memory are used 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.

Measurements can be made on selected segments using the full precision of the timebase.

Note: You cannot operate Serial Decoders on Sequence Mode acquisitions.