Thanks for considering the screenshot of my home’s electronic pulse …
I think you are right - there probably is more smart “tuning” Sense could do to squeeze out only the most important “transitions of interest”.
As for sampling, at a top level you are right - a 120Hz sample could be used to measure the power if three things were true:
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Sense could align the sampling directly at the peak of the 120Hz power waveform (see below). But line frequency drifts so sampling requires continuous readjustment (see @dave’s cool posting that shows line frequency drift here)
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Current was always in-phase with voltage - but it’s not. Motor and transformer displace current in one direction and capacitive loads pull the current waveform in the other, meaning real power (current x voltage) changes with different phase.
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And Sense only needed power / current / voltage to do identification. But it needs information like phase angles and probably things like estimated relaxation constants for transitions. Those require detailed sampling. You’re just not seeing this data on the transitions because it’s hidden behind a slick UI.
The picture below show the simple case of AC power, when both current and voltage are in-phase. Things get much more complicated when:
- Current and voltage are not in phase
- Current is not a nice sine wave - all the time in real life.
I’m an electrical engineer, and I think Sense has done a good job hiding all the ugliness behind complex AC measurements that I once had to do in lab. They may have made it so simple that users don’t even realize how hard AC measurements of power really are.