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Chapter 2 Hardware Overview
NI 5911 User Manual 2-8
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National Instruments Corporation
3. The linearity of the ADC is calibrated using an internal sinewave
generator as reference.
4. The time-to-digital converter used for RIS measurements is calibrated.
Note Do not apply high-amplitude or high-frequency signals to the NI 5911 during
internal calibration. For optimal calibration performance, disconnect the input
signal from the NI 5911.
External Calibration
External calibration is used to calibrate the internal reference on the
NI 5911. The NI 5911 is already calibrated when it is shipped from the
factory. Periodically, the NI 5911 will need external calibration to remain
within the specified accuracy. For more information on calibration, contact
National Instruments using the support information in Appendix C,
Customer Communication. For actual intervals and accuracy, refer to
Appendix A, Specifications.
Triggering and Arming
There are several triggering methods for the NI 5911. The trigger can be
an analog level that is compared to the input or any of several digital inputs.
You can also call a software function to trigger the board. Figure 2-3 shows
the different trigger sources. When a digital signal is used, that signal must
be at a high TTL level for at least 40 ns before any triggers will be accepted.
CBIHWum.book Page 8 Thursday, October 29, 1998 1:56 PM