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.
lxgr 22 hours ago [-]
It’s not available on iOS devices though, right?
redgridtactical 7 hours ago [-]
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!
RankingMember 1 days ago [-]
Cool idea, but doesn't Meshtastic already do this but with better range because it uses radio instead of BT?
redgridtactical 1 days ago [-]
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.
RankingMember 1 days ago [-]
Good points. I like the ghost marker functionality, helps with the shorter-range of BT.
redgridtactical 1 days ago [-]
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.
kazumaxwell1117 18 hours ago [-]
This is awesome! Does it have an alert feature? I'm also curious about battery life.
redgridtactical 7 hours ago [-]
There's haptic feedback when a peer connects or disconnects, and the ghost marker system gives you a visual alert when someone drops off the grid. Battery wise, there's an Ultra Expedition mode that drops BLE updates to once every 60 seconds and keeps drain under 2% per hour. In normal active mode it's more like 5 second intervals, so heavier on battery but way more responsive. You pick the mode based on how long you'll be out.
seriousmice 1 days ago [-]
Super cool idea! This would be amazing for Airsoft games
redgridtactical 1 days ago [-]
Definitely was one of the use cases I designed around!
shminge 1 days ago [-]
Very cool idea. What's the range of BLE connectivity? I can't imagine it gets far
redgridtactical 1 days ago [-]
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.
pokstad 10 hours ago [-]
This is exactly what I want for my family hikes. We carry walkie talkies right now, which is just one more thing. Awesome app!
redgridtactical 7 hours ago [-]
Thank you! Would love some feedback if you try it out!
idiotsecant 1 days ago [-]
Isnt the range of Bluetooth pretty much the range of a loud yell?
redgridtactical 1 days ago [-]
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.
sneak 2 hours ago [-]
Yeah the range of BLE makes this an order of magnitude less useful or practical than a $50 LoRa transceiver.
redgridtactical 2 hours ago [-]
All true, but the tradeoff is zero additional hardware cost and zero setup. For a family hike, small team, or a hunting party staying within a few hundred meters of each other, pulling out your phones beats buying and configuring radios for everyone.
That said, BLE Long Range (Coded PHY) pushes it to 400m-1km and is on the roadmap for the next version. I'm also planning a Meshtastic bridge so if you already own LoRa hardware, the app can route through it for multi-kilometer range. Best of both worlds: works without hardware, works better with it. Would love some feedback if you ever try it out!
jdyer9 20 hours ago [-]
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?
redgridtactical 7 hours ago [-]
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schobi 18 hours ago [-]
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.
redgridtactical 2 hours ago [-]
If you ever do get the chance to use, let me know what you think!
dualblocksgame 21 hours ago [-]
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Rendered at 02:47:32 GMT+0000 (Coordinated Universal Time) with Vercel.
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.
That said, BLE Long Range (Coded PHY) pushes it to 400m-1km and is on the roadmap for the next version. I'm also planning a Meshtastic bridge so if you already own LoRa hardware, the app can route through it for multi-kilometer range. Best of both worlds: works without hardware, works better with it. Would love some feedback if you ever try it out!
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.