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I once found my phone buried in the sand on a beach with no coverage. I had a year worth of pictures on it, so I stewed in anguish for almost a day until we tho
by jukea 3y ago
I once found my phone buried in the sand on a beach with no coverage. I had a year worth of pictures on it, so I stewed in anguish for almost a day until we thought about installing a Bluetooth signal monitor on a friend’s phone . Given the sluggish update frequency, we resorted to triangulating the phone’s position. As we were pulling it from its sandy grave, I swear it felt like we were cheating fate itself.
- lxgr 3y agoI recovered a lost device (satellite messenger in my case) via Bluetooth as well! It had just fallen into some ferns a meter or so off the trail, but without Bluetooth I'm sure I'd have never found it again.
- WanderPanda 3y agoNot to nitpick but I think you mean trilaterate ;)
- lxgr 3y agoIf we're being nitpicky it was probably neither – multilateration requires taking multiple measurements, drawing circles/lines of equal signal strength (or timing advance) and then intersecting these. If you just want to home in on a transmitter, there's a much simpler algorithm: Try walking into various directions and keep heading into the one that makes the signal strength nunber go up :) Not sure if there's a name for that.
- dharmab 3y agoDirection finding! https://en.wikipedia.org/wiki/Direction_finding https://en.wikipedia.org/wiki/Direction_finding
- lxgr 3y agoI was looking at that too, but doesn't that usually imply using a directional antenna, rather than just measuring the received signal strength at different locations?
- aarghh 3y agoNope - as everyone who has looked for a buried avalanche beacon knows. As a matter of fact, depending on the number of burials and the searchers, your optimal search technique may be different.
- jffry 3y ago> Not sure if there's a name for that. Hill climbing! https://en.wikipedia.org/wiki/Hill_climbing https://en.wikipedia.org/wiki/Hill_climbing Basically: Go in any direction that makes the number go up. Repeat.
- fsckboy 3y agoyou need a second rule: "Don't go in any direction that makes the number go down." That way, when you're on top of it, you know to stop.
- freshboy69 3y agoNo you don't. Go in the upward direction implies don't go in the downward direction
- fsckboy 3y agoI don't agree that that wording is as precise as you think it is. if you move in the direction where the signal goes up, when it stops going up, you are still moving in the same direction. Move "so long as the signal goes up" would tell you to stop, but it wouldn't tell you the direction, is the type of clarity I'm looking for.
- petemir 3y agoGradient ascent?
- TeMPOraL 3y agoOr gradient descent if you mentally negate the number in question. It's the same thing.
- WanderPanda 3y agoI think hill-climbing rejects updates that would worsen the objective while gradient descent usually doesn‘t
- smegsicle 3y ago"warmer colder"
- jukea 3y agoNice one, Yep this is it. We drew 3 rough circles and found the intersection
- deleted 3y ago[deleted]
- tkk13909 3y agoAnd this, kids, is why we back up everything