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Comment by georgeashworth | Hacker News Reader

Does this type of occupancy tracking work accurately outdoors? I'm assuming it would be difficult because signals would travel further. (My startup needs occupancy tracking for tennis courts.)

Maybe I could mount a BT device at a corner of the outdoor space and use its signal strength as the threshold value.

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If you want to get really spicy, you can use two antennas and an SDR to compute angle of arrival using nothing but a BLE advertisement's data . This is different from BLE AoA as it doesn't require a cooperative transmitter.

If you want to get really, really spicy, use three devices/antennas and you can roughly track in three-dimensional space.

there are wifi setups that allow you to do this already.

I would like to subscribe to this API.

Wouldn’t three dimensional tracking need four antennas?

Three appropriately spaced antennas will give you azimuth and elevation of a ray to the transmitter, but not distance.

But using two of the above in different, known locations would allow you to compute the intersection to a 3D location.

You could use the BLE AoA extension as well to derive an angle: https://www.bluetooth.com/blog/new-aoa-aod-bluetooth-capabil...

Did you consider using BT or UWB as a radar? On a tennis court you won't have any obstacles to worry about, I suspect it's relatively easy to solve.

UWB in particular is accurate enough to get breathing patterns...

It does but we don't have a battery powered option (yet) so power availability is the bigger issue. Our sensors can only be outlet powered. Each sensor can cover cover roughly 5,000 sq.ft. or about two tennis courts.

You could mount one at each corner and use a directional antenna to help.

You the same george ashworth that used to work at d&b?

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