LeCroy DDA-3000A, Operator'S Manual

Page: 87 / 437

X-Stream Operator’s Manual
WM-OM-E Rev I
85
SAMPLING MODES
Depending on your timebase, you can choose either Single-shot (Real Time) , Sequence
, or RIS mode sampling.
To Select a Sampling Mode
1. In the menu bar, touch Timebase , then Horizontal Setup... in the drop-down menu.
2. In the "Horizontal" dialog, touch a Sample Mode button.
3. If you chose Sequence Mode , touch the "Smart Memory" tab, then touch inside the Num
Segments data entry field and enter a value, using the pop-up
numeric keypad.
4. If you want to use a timeout condition for Sequence mode, touch the Enable Timeout
checkbox; then touch inside the Timeout data entry field and enter a value,
using the pop-up numeric keypad.
Single-shot sampling mode
Basic Capture Technique
A single-shot acquisition is a series of digitized voltage values sampled on the input signal at a
uniform rate. It is also a series of measured data values associated with a single trigger event. The
acquisition is typically stopped a defined number of samples after this event occurs: a number
determined by the selected trigger delay and measured by the timebase. The waveform's
horizontal position (and waveform display in general) is determined using the trigger event as the
definition of time zero.
You can choose either a pre- or post-trigger delay. Pre-trigger delay is the time from the left-hand
edge of the display grid forward to the trigger event, while post-trigger delay is the time back to the
event. You can sample the waveform in a range starting well before the trigger event up to the
moment the event occurs. This is 100% pre-trigger, and it allows you to see the waveform leading
up to the point at which the trigger condition was met and the trigger occurred. (The instrument
offers up to the maximum record length of points of pre-trigger information.) Post-trigger delay, on
the other hand, allows you to sample the waveform starting at the equivalent of 10,000 divisions
after the event occurred.
Because each instrument input channel has a dedicated ADC (Analog-to-Digital Converter), the
voltage on each is sampled and measured at the same instant. This allows very reliable time
measurements between the channels.