High-Speed Digitizers

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Captuing data in I16 format for smaller data footprint vs DBL

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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.

 

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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.

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019OxsSAE&l=en-US

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