
Stanford researchers develop new method for waking up small electronic devices - breck
https://news.stanford.edu/press/view/18900
======
JoeAltmaier
Some of us remember TV remote controls that operated ultrasonically. They were
terrible - somebody rattles their keys or the dog walks by with its metal
collar clinking - lots of ultrasonic noise created by those events and Chunk-
Chunk-Chunk you would be three channels away from your nightly news.

~~~
lnanek2
Seems solvable in this case. Ultra-sound can wake up the device, but then it
would take some other signal to have it do anything other than go back to
sleep, like WiFi/Bluetooth/LAN/etc.. So you wouldn't get incorrect
functionality triggering from accidental ultra-sound triggers, you'd just save
less battery.

------
mar77i
My little brother used to do electrical installations. He once set up a device
that deactivated the power in a building as soon as no more consumers were on.
Of course that thing is probably still using power continuously itself.

On that same note, shouldn't it be possible to install a mechanism that
doesn't use any power at all? Something like, uh, I'm not gonna say a light
switch, but a weightless switch, to mix a few metaphors here.

~~~
pjc50
It consumes 8 nanowatts, which is well below the self-discharge rate of almost
all batteries.

~~~
jackhack
only nanowatts? With an antenna, could this low level of power be drawn from
radio/TV signals? It is enough to power a crystal set radio receiver.

~~~
junkcollector
Nanowatts are -60 dBm or what you would expect to receive on your cellphone
when you have decent but not great signal. Many radios operate down to the
-110 dBm/MHz PSD or lower ranges for high performance stuff. So you could use
hits those power levels with energy harvesting on radio waves but only if you
were in the right location, on the right band, and it would possibly cause
problems for the systems that are trying to use those signals for their
intended purposes.

------
pishpash
This isn't novel. As an idea, signal amplification being used for switching
has been around forever. Plus this thing still draws power. A completely
passive receiver is possible.

~~~
amelius
Yes, I was expecting a receiver that draws power from the received signal.

------
hguhghuff
It's the security and privacy implications that come to mind for me.

~~~
craftyguy
Care to elaborate how this applies? The article is about a switch. The
alternative to a switch is to leave the device on full-time, or implement some
self-resuming feature using a RTC. Both of those require constant power. I
don't think any of this has anything to do with 'security/privacy
implications', so some examples would be appreciated!

