LeCroy USB Mobile HS, Руководство пользователя

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USB MobileHS User Manual Chapter 10: Recording Options
LeCroy Corporation
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Buffer Size
You can adjust the size of the recording buffer from 0.4 megabytes to 64 megabytes.
The Recording type option determines how this buffer is used. Although there are 64
megabytes of physical memory in the Analyzer, 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.
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 16MB, then for the following Trigger Position
settings, the amount of pre- and post-Trigger data is:
• 95% post-triggering: 0.8MB pre-trigger, 15.2MB post-trigger
• 75% post-triggering: 4MB pre-trigger, 12MB post-trigger
• 50% post-triggering: 8MB pre-trigger, 8MB post-trigger
• 25% post-triggering: 12MB pre-trigger, 4MB post-trigger
• 5% post-triggering: 15.2MB pre-trigger, 0.8MB post-trigger
Note: When a Trigger occurs, recording continues until the post-Trigger amount of
the buffer is filled or when
Stop is selected.
Options Name
The Options Name is a descriptive label of the current Recording Options settings.
Options Names are associated with files that have a .rec suffix.
The default option name is default . Default preserves the current Recording Options
settings.
The purpose of the Options Name box is to give you a place to preserve different
Recording Options that you use on a recurrent basis. For example, if you use two or three
different Recording Options configurations, you can save these configurations and load
them the next time they are needed.
Because Options Names are descriptive labels and not file names, you can enter in any
text you like into the box. Your labels can be very descriptive such as "Trigger on High
Speed traffic when CRC errors occur."