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Comment by varenc | Hacker News Reader

The U1 ultra-wideband chip means the HomePod can be used a fixed reference point for general purpose indoor location finding! Would be great for AirTags, if those ever become a reality.

At the moment, the U1 is only be used for the nifty hold-your-iphone-close move, but I have no doubt Apple has other applications in mind. Ultra-wideband is amazing for its indoor high-resolution position finding. Down to the inch is possible. But the more reference points you have, the faster/more accurate it will be.

When used with the U1 chip also in your iPhone, having a HomePod mini around could enable Apple's forthcoming AirTags to be located more quickly/precisely. Or enable a better AR experience. They're basically GPS satellites for in-home position finding. (Ultra-wideband uses time-of-flight, just like GPS)

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I’d really like to see a future where HomePod Minis with the U1 enable my phone to precisely track its own location as I move throughout the house, with automations as I go from room to room, or with songs following me between rooms, or letting me ask Siri for a precise location of my phone.

The U1 and the Homepod-Mini really will make this possible! It seems like you'd need more than one Homepod to easily triangulate position, but by leveraging the precise accelerometers on the phone and taking multiple distance measurements from the Homepod's U1 chip, that alone might be enough to give you pretty precise location.

I really wish of a future where I can just point my phone at one of my cast devices to cast to it.

A very limited version of this feature is used in AirDrop with U1 equipped iPhones. Just point your phone to the phone you are transferring to and it shows up in the AirDrop share sheet.

Was that actually implemented / tested? I remember hearing about it but I never saw anyone mention or test it in any reviews. Does it actually work well?

It does exist, and it works! But both phones need U1 chips, meaning iPhone 11s and above.

One thing that's cool about this is that iOS must be using the slight movements of the phone in your hand to help triangulate the other phone. Ultra-wideband position finding relies on time-of-flight, so from a single reference point you only know the precise distance something is from you, and not its direction. To get around, my guess is iOS is using the accelerometers in the phone to measure slight changes a phones position, and then using multiple ultra-wideband distance measurements from those different positions to triangulate the other phone.

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