Chapter2 HardwareOverview
©NationalInstruments Corporation 2-5 NI5911 User Manual
analysis,distortion analysis, and other measurements for which high
resolution is crucial.
Oscilloscope Mode
The ADC converts at a constant rate of 100 MS/s, but you can choose to
store only a fraction of these samples into memory at a lower rate. This
allowsyou tostore waveforms using fewer data points and decreases the
burden of storing, analyzing, and displaying the waveforms. If you need
fastersampling rates, you can use Random Interleaved Sampling (RIS) to
effectively increasethe sampling rate to 1 GS/s for repetitive waveforms.
In oscilloscope mode, all signals up to 100 MHz are passed to the ADC.
Youneed to ensure that your signal is band-limited to prevent aliasing.
Aliasing and other sampling terms are described more thoroughly in your
NI-SCOPE Software User Manual.
Sampling Methods—Real-Time and RIS
Thereare two sampling methods available in oscilloscope mode, real-time
andrandom interleaved sampling (RIS). Using real-time sampling, you can
acquire data at ar ate of1 00/nMS/s,wherenis a number from 1 to 232.
RIS sampling can be used on repetitive signals to effectively extend the
sampling rate above 100 MS/s. In RIS mode, you can sample at rates of
100 MS/s × n, where nis a number from 2 to 10.
Flexible Resolution Mode
Table 2-2 shows the relationship between the available sampling rates,
resolution, and the corresponding bandwidth for flexible resolution mode.