How to Improve Signal Quality of HSDIO Cards

Updated Jan 6, 2020

Reported In

Hardware

  • PXIe-6544
  • PXIe-6545
  • PXIe-6547
  • PXIe-6548

Driver

  • NI-HSDIO

Issue Details

I'm seeing poor digital signal quality when generating data at a high speed on my HSDIO card, how can I improve it?

Solution

It's common for digital signals to degrade while acquiring at high speeds. Often times signal integrity issues are incorrectly characterized by issues with the card generating the data, but can easily be fixed by implementing sensible and easy impedance and noise control. Here are some initial tips to help fix digital signal integrity issues:
1) Be deliberate about impedance control. Match the impedance of the cable with respect to the impedance of the card.
2) Reduce reflections. Try to only use SMB or BNC instead of bare lead wires and break out boards. Reduce the number of cables in the circuit.
3) Use twisted pair cables such as the SCH68-C68-D4 to reduce the effect of noise.
4) Avoid electromagnetic interferences such as lamps.
5) Take data at a lower speed to examine the signal quality across speeds.