High-Speed Digitizers

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Captuing data in I16 format for smaller data footprint vs DBL


The VI acquires data in I16 format, instead of DBL using the NI poly fetch VI. This enables me to collect data at a high rate (1.25GS/Sec) and also stream it to the disk without running into bottlenecks. However, the collected data is later analyzed and the values need to be precise (single/double).


Therefore, what's the best way to get precision decimal data in this scenario? That is to collect data in I16 format and write data as DBL ? My consumer loop Queue is initiated as I16, is it possible to convert the values before I write them to the TDMS ? Since this is a precise measurement setup, the requirement is that the data should be in decimal format.



NI System Configuration:
- NI PXIe-1071, 4-Slot 3U PXI Express Chassis , 1 GB/Slot throughput, Part Number: 781368-01
- NI PXIe-PCIe8381,x8 Gen2 MXI-Express for PXI Express Interface,3m, Part Number: 782522-01
- PXIe-5160 PXI Oscilloscope, 500 MHz, 10 bits, 2.5 GS/s, 2 Channels, 64 MB, Part Number: 782621-01
- Astronics PXIe-1209 2-Channel, 100 MHz PXI Pulse Generator, Part Number: 785033-01
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If your application and PC permits, you can convert the I16 data into DBL on your consumer loop before saving it to the TDMS file, but it would consume a lot of memory during your measurement.

During the measurement, you can intermittently save the data as I16 on a TDMS file, and after the measurement, you can reopen the file you just made and convert the I16 ADC data to real voltage.

The conversion method is described below.


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