Teledyne LeCroy USBTracer_Trainer - Users Manual - Manual (Page 248)

Chapter 10: Recording Options USB Protocol Suite User Manual
234
LeCroy Corporation
10.1.6 Buffer Size
You can adjust the size of the recording buffer from a very small size up to the maximum
available in your product.
The Recording type option determines how this buffer is used. Although the Analyzer
has a large physical memory, the efficiency of the recording is about a 2:1 ratio of physical
memory to actual USB traffic. Shorter USB packets yield a slightly less efficient recording.
The non-traffic portion of physical memory is utilized for control and timing information.
Note: The scale is not linear and affords more granularity in the smaller buffer
sizes.
Note: To make the full buffer available for recording, you can select to
Disable Generator Memory in the Misc.USB 2.0 tab of the
Recording Options dialog.
10.1.7 Trigger Position
You can adjust the amount of recording to be done post-trigger or select where you want
the Trigger located within the defined buffer. You can adjust the Triggering Position
between 1 and 99% post-trigger. Trigger Position is available only when
Manual Trigger or Event Trigger is selected as Recording type.
As an example, if the buffer size is set to 16 MB, then for the following Trigger Position
settings, the amount of pre-trigger and post-trigger data is:
• 95% post-triggering: 0.8 MB pre-trigger, 15.2 MB post-trigger
• 75% post-triggering: 4 MB pre-trigger, 12 MB post-trigger
• 50% post-triggering: 8 MB pre-trigger, 8 MB post-trigger
• 25% post-triggering: 12 MB pre-trigger, 4 MB post-trigger
• 5% post-triggering: 15.2 MB pre-trigger, 0.8 MB post-trigger
Note: When a Trigger occurs, recording continues until the post-trigger amount of
the buffer is filled or when Stop is selected.