r/mildlyinfuriating • u/notworkingghost • 8h ago

Ruined by Technology When we’re not looking, Alexa displays the wrong time. I finally caught her on video.

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u/SirTheBob 7h ago

Simply put: radar works by monitoring the return bounce of soundwaves. Wifi signals can be used in much the same way. Any device that emits and receives wifi can see you.

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u/cinnasota 6h ago

the device heard a voice prompt

I'm guessing you mask up walking amongst trees, lmao

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u/ascarymoviereview 2h ago

Can they see all of me?

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u/reckless_responsibly 6h ago

You described sonar. Radar uses radio waves.

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u/Ultrasonic-Sawyer 4h ago

In a janky way they also were right with sound waves as these use ultrasound instead of radar. 

Too many variables. Lets just call it voodoo witchcraft. 

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u/Wild-Video-5317 6h ago

Looks like the Echo Show.  It has a camera.  It was marketed that you'd be able to have it take your picture, and then it'd give you a little "virtual try on" of clothing from the amazon store.

The camera is sufficient for detecting movement, obviously.

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u/Ultrasonic-Sawyer 4h ago

Although I think the show also uses ultrasound. 

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u/unicodemonkey 3h ago edited 3h ago

In a very inefficient way though, basically just a worse version of a dedicated presence sensor. I think it works not by bouncing actual RF pings off the target but by monitoring signal level changes in received packets (against known references, i.e. stationary wifi devices like a printer) when someone gets in the way.

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u/MarlinMaverick 7h ago

That used to be a conspiracy theory 

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u/SirTheBob 7h ago

Some modern home PCs use/sell it as a feature that wakes the PC up as you enter the room or approach it.