Resampling Reference Channel Switch

[mbremer]

Hi,

I'm reviewing the examples that come with the Electrical Power Toolkit (using this whitepaper as a reference).  There is one section that I'm having trouble understanding.  The second loop is responsible for re-sampling the signals, but the reference channel is being chosen in the first loop using logic that looks like the following.

From what I can tell it tracks the maximum amplitude from all input channels and re-selects the reference channel if the selected reference goes outside some bounds.  It also resets the tracked max amplitude every 10,000 calls.

I haven't been able to figure out what the purpose of this VI is.  Why do we need to dynamically re-select the re-sampling reference channel if the current reference goes outside some bounds?  Why can't we just use the first voltage channel?  I haven't found anywhere that describes the problem that this VI is solving.  Can anyone provide some insight?

[Yifan.Liu · Accepted solution]

The resampling vi resamples the signals based on the zero crossing positions calculated from the signal of the reference channel. If the signal of the reference channel become too weak, the calculated zero crossings may not be accurate, which will further influence the resampling results.

The Reference Channel Switch vi is used for ensuring the reference signal to be valid enough for zero crossing calculation.

[mbremer]

Ahh, that makes sense.  Thanks!