Quite smart idea, not for throttling when the fans are heard, but SPEEDING THEM UP while they are NOT heard, based on the noise floor of the current environment.
This, combined with an assessment how much of the environment the user currently hears (i.e. maybe he is watching a movie), could provide a lot of headroom for additional cooling without bothering the user.
Another trick is not to use constant RPM because you can hit some mechanical resonance point, but constantly varying RPM around target RPM so that the system even if it hits resonance stays there only for a brief moment and won't start vibrating.
They do the same with clock signals in some systems. Similar idea to avoid high peaks at a single frequency:
> Spread spectrum clocking is a technique used in electronics design to intentionally modulate the
ideal position of the clock edge such that the resulting signal’s spectrum is “spread”, around the
ideal frequency of the clock. In timing circuits, this has the advantage of reducing Electromagnetic
Interference (EMI) associated with the fundamental frequency of the signal.
This is controversial, because the same amount of noise is emitted, just with a different shape that is still able to be picked up by radio receivers just as well, but is more likely to pass regulatory tests.
For VR perf its probably a bad idea to throttle the performance. A better goal would be to balance user comfort. You can trade noise for thermal comfort.
I can't speak for Apple, but for my Prusa 3D-printer: Worn/cheap ball bearings will make a rattling sound until they heat up and the balls expand. If you care about the auditory experience, using audio in the feedback loop makes some sense.
The goal is probably not to absolutely manage cooling but to focus on the audio experience and try to keep noise below some threshold.
I think that's an interesting idea, even if not everyone might be happy with the tradeoff (comes down to how much you care about noise vs getting throttled), especially for a vr device.
Because the RPM of a fan is not a 100% reliable indicator of its loudness. Sometimes a lower speed can even be louder than a higher one, because of certain resonances...
Makes sense. Humans are really bad at perceiving the environmental noise floor. Our brains just tune it out, but it is has a huge impact on your perception of the loudness of fans that you've strapped to your face.
Twitter doesn’t show threads to people who are not logged in (e.g. if you don’t have an account). Shaming people for not reading what they can’t see (or even know exists) is unfair. Using archival sites doesn’t work as a bypass like on newspaper sites.
Not to mention people on Firefox, which from what I have read on HN might not even have access to it at all.
Twitter links should probably be downranked on HN until (if/when) they return to being more accessible.
That is definitely done for bearing in ratting machinery. You can often even pinpoint which bearing is damaged and which part of that bearing is damaged, based on the frequency spectrum.
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This, combined with an assessment how much of the environment the user currently hears (i.e. maybe he is watching a movie), could provide a lot of headroom for additional cooling without bothering the user.
> Spread spectrum clocking is a technique used in electronics design to intentionally modulate the ideal position of the clock edge such that the resulting signal’s spectrum is “spread”, around the ideal frequency of the clock. In timing circuits, this has the advantage of reducing Electromagnetic Interference (EMI) associated with the fundamental frequency of the signal.
https://www.microsemi.com/document-portal/doc_view/135439-wh...
Noisy environment: turn the fans all the way as the user -> more cooling -> processor doesn't throttle
Quiet environment: turn the fans down -> processor throttles
I think that's an interesting idea, even if not everyone might be happy with the tradeoff (comes down to how much you care about noise vs getting throttled), especially for a vr device.
To avoid the imperfection of a bit of fan noise, throttle the entire experience. Great.
The reason proposed is that if the environment is loud, you won't be bothered by additional noise from the fans.
Twitter doesn’t show threads to people who are not logged in (e.g. if you don’t have an account). Shaming people for not reading what they can’t see (or even know exists) is unfair. Using archival sites doesn’t work as a bypass like on newspaper sites.
Not to mention people on Firefox, which from what I have read on HN might not even have access to it at all.
Twitter links should probably be downranked on HN until (if/when) they return to being more accessible.
https://www.analog.com/en/lp/001/machine-health-sensing.html
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