Viewing Time Stamps; Ris Sampling Mode - For Higher Sample Rates - LeCroy SDA Operator's Manual

Viewing Time Stamps

1. In the menu bar, touch Timebase, then touch Acquisition Status... in the drop-down menu.
2. Touch the Time tab.
3. Touch one of the channel buttons under Select Waveform.
4. Touch inside the Select Segment field and enter a segment number, using the pop-up
keypad.

RIS SAMPLING Mode - For Higher Sample Rates

RIS (Random Interleaved Sampling) is an acquisition technique that allows effective sampling
rates higher than the maximum single-shot sampling rate. It is used on repetitive waveforms with
a stable trigger. The maximum effective sampling rate of 50 GS/s can be achieved with RIS by
making 100 single-shot acquisitions at 500 MS/s. The bins thus acquired are positioned
approximately 20 ps 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, measured by the timebase to 5 ps resolution.
The instrument requires multiple triggers to complete an acquisition. The number depends on the
sample rate: the higher the sample rate, the more triggers are required. It then interleaves these
segments (see figure) 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. The oscilloscope is capable of acquiring approximately 40,000 RIS
segments per second.
Note: RIS mode is not available when the scope is operating in Fixed Sample Rate mode. When the SDA 18/13/11/9000
is operating in 18/13/11/9 GHz mode, RIS mode sampling is not available.
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