How it works

TopoKin moves your group's positions and messages two ways:

Over the internet, when your phone has signal (cell or Wi-Fi). Nothing else needed.
Radio to radio, when it doesn't. Each phone pairs with a small Meshtastic radio over Bluetooth, and the radios talk to each other for miles with no towers.

Past cell signal, a phone without a radio is on its own. Its map, GPS and your saved places keep working, but it can't see anyone new or be seen. Seeing your kin, messages, rally points and trackers all go through the radios.

What works where

	Phone, with signal	Phone, no signal, no radio	Phone + radio, no signal
Offline maps, GPS, your places	✓	✓	✓
See your kin, and be seen	✓	✗	✓ within radio range
Messages	✓	Wait until you have signal	✓ within radio range
Trackers' dots	✓ if a radio in the group hears them	✗	✓ within radio range
Rally points	✓ on everyone's phone	Only on your own map	✓, and on trackers' screens

Past signal: the whole picture

No cell signal and no internet anywhere. This is all it takes:

Emma's tracker (orange) reaches Ann's radio, Ann's radio passes it on to Ben's, and each radio hands it to its phone. Ben's own position (green) goes back the same way. Both phones show Emma, Ann and Ben.

Set up like this (with signal, before you go):

Ann and Ben have TopoKin and are in the same group (Getting started).
Ann pairs her Wio Tracker L1 with her phone: Group › Radios › Your radio › Pair (how).
Ben pairs his ThinkNode M3 with his phone the same way (it has no screen, so the PIN is 123456).
Ann hands the SenseCAP T1000-E to Emma: Group › Radios › Hand out a radio (how). Clip it to her pack.
Everyone gets maps for the area and taps Ready?.

That's it. Past signal, both phones show Emma, Ann and Ben, and messages and rally points travel the same way. Any of the tested radios can fill any spot; these are just one way to do it.

The rest of this page takes it apart, with and without signal:

InternetBluetooth (phone to its radio)Radio to radio

With signal: the internet does it

Both have signal: no radio needed. This is how it works around town and at home.

No signal: the radios carry it

Each phone hands what it sends to its own radio, the radio sends it to the others, and their radio hands it to their phone.

The RADIO light at the top of the map is green when your phone and radio are connected. Your radio has to be on and near your phone (Bluetooth reaches across a campsite, not across a valley).

No signal and no radio: cut off

A phone can't hear radios by itself. Ben sees no one move and no one sees him until he has signal again.

Ben's map still works, with his own dot, offline maps and saved places. What he sends waits until he has signal.

Trackers: someone's radio has to hear them

A tracker is a radio on its own, carried by a kid, a guest or the dog. It only talks radio. Its dot reaches the group through a radio paired to a phone. Other radios pass it along, and a phone with signal passes it on over the internet too.

Ann's radio hears Emma's tracker. Ann's phone has signal, so it passes Emma's dot on: Ben sees her without a radio of his own.

Signal or not, if no one's radio is on, Emma's dot stays where it was last heard.

Trackers need a radio in your group. At least one phone in the group needs its own radio, paired and on, near enough to hear the trackers. Without one, handing out the trackers still works, but their dots never move.

TopoKin warns you when trackers are out and no one's radio is on: a red No radio is on chip on the map, a red item in Ready?, and a note when you hand one out. Group › Radios shows whose radios are hearing them.

Radios pass it on

Every radio in the group repeats what it hears, so a radio in between can link two that are too far apart or behind a ridge.

No phone needed at the middle radio. A radio in the car at the trailhead is a good one.

Signal for some, not others

A common day: Ann at camp has signal and a radio, Mark on the trail has only his radio, Grandpa at home has only signal.

Trackers reach everyone: Ann's phone passes what her radio hears on to the internet, so Grandpa sees the kids' dots too.
Mark reaches Ann radio to radio. His messages and dot don't hop from Ann's phone onto the internet, so Grandpa sees Mark again when Mark has signal.
Grandpa's messages reach Ann over the internet. They go out by radio only from Grandpa's own phone (he has no radio), so Mark gets them when he has signal.

What each person needs

Who	In signal	Past signal
Kin with the app	Their phone	Their phone and their own radio, paired and on
Kin without a phone (a kid, a guest, the dog)	A tracker	A tracker
The group	At least one radio paired to a phone and on, near the trackers	Same
Back home	Their phone: they see trackers through whoever hears them
Optional		A spare radio in the car or at camp, to reach further

The smallest kit for a trip past signal: one radio for each phone going out there, plus one for each tracker. See Which radio.

Next: Radios and trackers.