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.
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.
Meshtastic is great if you're willing to carry extra hardware. Everyone in your group needs a LoRa radio (which can range from $30-50 each), and you need to pair them, flash the firmware, configure channels, etc. For a SAR team or preppers who already own the gear, it's definitely a solid choice.
Red Grid Link was more so for those already carrying their phones and those that don't want to buy anything else. The trade-off is range for convenience. BLE gets you maybe ~50-100m in the open, ~20-60m in densely woooded areas. That's enough to keep tabs on a hunting party spread across a hillside or a hiking group. Absolutely not a replacement for a radio relay across a valley.
Different tools for different problems. If I need a 2km mesh range I'd set up Meshtastic too.
Thanks, yeah the ghost markers ended up being one of those features that came out of necessity. Once I accepted that the BLE range was never going to be amazing, the question became what happens when someone drops off? Felt wrong to just remove them from the map.
It's not long range by any stretch. The use case is more "my group split up on a trail and I want to know which fork they took" vs "track someone across a mountain." The ghost marker system helps here too. If someone walks out of range, their last known position and direction stays on your map, so you at least know where they're heading and how long ago they traveled that direction.
Haha fair point. In open terrain you get maybe 50-100m which I agree, not far. In practice it's more useful than it sounds though. You don't need miles of range when the point is "where did my buddy go 5 minutes ago." And if they walk out of range their last position and heading stick on your map as a ghost marker so you're not totally blind or left guessing.
This comment got me thinking that it might be worth using their second-to-last location to try and derive some vector. Obviously that's super informative as you already know the edge of the map they left, but maybe it's useful?
Well... I have a hard time imagining to get location by yelling "where are you? " "by the trees!"
It really sounds immensely useful to know last location (while they were still in range).
Use case: I was out, picking wild lingonberries in the forest with a group of ~10, some kids. At a "secret" location, with everyone wandering off in a direction they see more of them. Shouting did not help much.
https://novelbits.io/bluetooth-long-range-coded-phy/
Red Grid Link was more so for those already carrying their phones and those that don't want to buy anything else. The trade-off is range for convenience. BLE gets you maybe ~50-100m in the open, ~20-60m in densely woooded areas. That's enough to keep tabs on a hunting party spread across a hillside or a hiking group. Absolutely not a replacement for a radio relay across a valley.
Different tools for different problems. If I need a 2km mesh range I'd set up Meshtastic too.
Use case: I was out, picking wild lingonberries in the forest with a group of ~10, some kids. At a "secret" location, with everyone wandering off in a direction they see more of them. Shouting did not help much.