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I just read

Bluetooth Direction Finding, added to the Bluetooth spec as part of Bluetooth 5.1 to allow devices to measure angle of arrival and angle of departure (AoA and AoD) to position devices to an accuracy of under one metre (around 3.3 feet.)

(read it here).

I am excited about the idea, but want to be sure that I have understood it.

If I want to track people/objects and report their locations to a server, I imagine that I need a BLE Gateway/router.

I assume that the devices would send advertising packets, the gateway would receive these, detect the device location and send it via HTTP(S) to the server.

I also assume that only the BLE gateway/router needs to be BLE 5.1, since it is the one performing direction finding.

Are my assumption correct? Does it work that way? Can a BLE 5.1 gateway perform direction finding on a BLE 4.0 advertisement?

I welcome any more info, such as tutorials, videos, books, etc

Mawg
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1 Answers1

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The way Bluetooth direction finding works is described in this document.

There are two scenarios:

  • AoD (Angle of Departure):

    • Sending device sends a "direction finding signal"
    • Sending device is equipped with a "phased array antenna"
    • Receiving device performs "IQ Sampling"

  • AoA (Angle of Arrival):

    • Sending device sends a "direction finding signal"
    • Receiving device is equipped with a "phased array antenna"
    • Receiving device performs "IQ Sampling"

As you see, in both scenarios, there are requirements on both ends. Some are definitely hardware upgrades (the phased array antenna). The rest (IQ sampling and sending the direction finding signal) may be possible with just firmware / software upgrades, depending on the exact implementation, though I kind of doubt it (it would also most likely require at least a change in the BLE chip firmware, not just a high-level OS/app change).

So, as far as I understand it at this point, you need BT 5.1 equipment at both ends to make it work.

I'd love to hear otherwise!

jcaron
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