How to Change the Sampling Rate of 5170R Oscilloscope?

Updated Apr 17, 2018

Reported In

Hardware

  • PXIe-5170

Driver

  • LabVIEW Instrument Design Libraries for Reconfigurable Oscilloscopes

Programming Language

  • LabVIEW G

Issue Details

I am using the Stream To Host (NI PXIe-5170R/5171R) sample project for acquiring data from the NI PXIe-5170R/5171R reconfigurable oscilloscopes. I want to change/configure my oscilloscope to acquire at 10MHz or at different sample rate. How can I do this?

Solution

The 5170R has a fixed acquisition/sampling rate or ADC clock frequency of 250MS/s. To adjust the sampling rate, You have to change the DSP decimation factor control available in the Stream To Host (Host).vi front panel (refer to the below image). The decimation factor is divided by "N" decimation from 250 MS/s where "N" is 16 bit.



You also can create a custom decimation filter. To do that, you will have to modify or replace the existing integer decimation.vi present in the Stream To Host (FPGA).vi as shown below.

Additional Information

Decimation Example: If you want to acquire at 10 MHz, the easiest thing to do would be to sample the I/O at 250MHz and then decimate the data by a factor of 25 (i.e. retain one in every 25 data points and discard remaining samples).

External Clock: If you want to use an external clock, please make sure you refer to the specifications in order to provide the correct clock signal to the device. The performance of the PXIe-5170R will be dependent on the quality of the clock source.

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