National Instruments NI 5102 用户手册
Chapter 4
Hardware Overview
© National Instruments Corporation
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Random Interleaved Sampling
The NI 5102 supports Random Interleaved Sampling (RIS), a form of
Equivalent Time Sampling (ETS) which allows multiplication of the
maximum real-time sampling rate. The maximum interpolation factor
on the NI 5102 is 50, resulting in a maximum effective sampling rate
of 1 GS/s. At this rate, the ratio of logical bins to physical bins is
approximately 1:9. The minimum RIS rate is 40 MS/s.
Equivalent Time Sampling (ETS) which allows multiplication of the
maximum real-time sampling rate. The maximum interpolation factor
on the NI 5102 is 50, resulting in a maximum effective sampling rate
of 1 GS/s. At this rate, the ratio of logical bins to physical bins is
approximately 1:9. The minimum RIS rate is 40 MS/s.
To reconstruct the waveform with RIS, you need to know the RIS OFFSET,
which is the minimum value that the Time-to-Digital Converter (TDC) can
return, and the range of values, RIS GAIN, which is the maximum TDC
value minus the minimum TDC value.
which is the minimum value that the Time-to-Digital Converter (TDC) can
return, and the range of values, RIS GAIN, which is the maximum TDC
value minus the minimum TDC value.
RIS OFFSET and RIS GAIN may vary slightly from digitizer to digitizer.
Both these parameters are computed individually for each digitizer at the
factory and the values are stored in the onboard EEPROM.
Both these parameters are computed individually for each digitizer at the
factory and the values are stored in the onboard EEPROM.
Use RIS GAIN to determine the number of physical bins per logical bin for
the desired interpolation factor. You could use RIS OFFSET to start the
waveform reconstruction at the origin, but this parameter may drift over
time and temperature, which could result in an inaccurate waveform.
the desired interpolation factor. You could use RIS OFFSET to start the
waveform reconstruction at the origin, but this parameter may drift over
time and temperature, which could result in an inaccurate waveform.
Note
ETS and RIS work only with repetitive signals.
For an in-depth discussion of these concepts and how to use RIS, see
Chapter 5, Tasks and Examples, in your NI-SCOPE Software User Manual.
Chapter 5, Tasks and Examples, in your NI-SCOPE Software User Manual.
Calibration
Calibration is the process of minimizing measurement errors by making
small circuit adjustments. All NI 5102 digitizers come factory calibrated to
the levels indicated in Appendix A,
small circuit adjustments. All NI 5102 digitizers come factory calibrated to
the levels indicated in Appendix A,
. However, your digitizer
needs to be periodically recalibrated in order to maintain its specified
accuracy. You have two choices for recalibration, internal (or self)
calibration, and external calibration. A third option, external restore,
restores the factory settings and should be used only in the event of an
internal calibration failure.
accuracy. You have two choices for recalibration, internal (or self)
calibration, and external calibration. A third option, external restore,
restores the factory settings and should be used only in the event of an
internal calibration failure.
Internal calibration is executed with an NI-SCOPE software call or a
LabVIEW VI. It requires no external connections and adjusts only the
timing for RIS acquisitions. It should be performed upon installation of
LabVIEW VI. It requires no external connections and adjusts only the
timing for RIS acquisitions. It should be performed upon installation of