[svpk]

Have you looked at Bluetooth LE Long Range? I believe more recent phones have it and it claims communication of up to 1km. In practice less in the woods I'm sure. Still a dramatic win over standard Bluetooth though.

https://novelbits.io/bluetooth-long-range-coded-phy/

[redgridtactical]

BLE Coded PHY is on my radar. The theoretical range boost is huge, something like 4x over standard in ideal conditions. The challenge right now is that flutter_blue_plus (the BLE library I'm using) has limited support for negotiating Coded PHY, and both devices need to support it. But phone hardware has been shipping with it since around 2020 so the install base is there. Definitely something I want to add, probably as an automatic upgrade when both peers support it.

[lxgr]

It’s not available on iOS devices though, right?

[redgridtactical]

Yeah iOS supports BLE Coded PHY since the iPhone 12 / iOS 14. The tricky part is negotiating it at the library level. flutter_blue_plus doesn't fully expose Coded PHY yet so I'd need to handle it through platform channels on both sides. It's on my list though, the range improvement would be significant!

[lxgr]

Oh, I thought that support was only present in some iOS 13 beta and then disappeared again? (At the OS/driver level; I’m pretty sure the hardware supports it.)

If it’s really available, that would be amazing!

[redgridtactical]

You're right, I was wrong about iOS 17 auto-negotiating Coded PHY. After digging deeper, Apple did support it briefly in iOS 13.4 betas but pulled it in iOS 14 and it hasn't returned. CoreBluetooth still doesn't expose PHY selection at all. The iPhone hardware supports it but the OS won't use it. So BLE Long Range is going to be Android-only for now. I've updated the roadmap to reflect that.