This guide is about a convoy of cars on the same route - a few
families travelling together, a group of friends - through areas
where cellular signal fades in and out or disappears. It differs
from
Motorcycle Group Communication Without Cell Service
in a few ways: a car is a closed metal box, the convoy usually
spreads out further, and there's room to carry more equipment.
The problem: the convoy spreads out exactly where there's no signal
On a long route, the cars don't keep an even gap. One stops for a
photo, one drives slower, one takes a wrong turn. In the city this
is fine because you can call or text right away. But the best
stretches of a road trip are usually also the ones furthest from any
town - and that's when "losing a car" becomes a real problem,
because there's no way to message each other.
The base layer: route and stop plan
Before you go, agree on the main route and the stops - fuel
stations, places to eat, viewpoints - as regroup points. The simple
rule: if you get separated, drive to the next planned stop and wait.
Share the route with every car in advance, ideally in a form that
works offline. This still works when every device fails.
Download an
offline map for the whole
route on the navigator's phone in each car, and mark the stops as
shared landmarks.
The internal layer: messaging and location between cars
When there's no signal, Nelos lets the cars message each other and
see each other's location with no tower. Each car has one person
carrying a small device connected to a phone; the devices talk
directly to each other. Each car sees the other cars' latest
location on a shared map, can send "my car's stopped at km 30, keep
going without me", and has a "Need Help" button. You can start
using it for free.
Mounting a radio device inside a metal vehicle
A car's metal body attenuates radio signal considerably - this is
why FM reception drops in a tunnel, and why cars usually have an
external antenna. For a LoRa radio device, this means:
- Place the device near a window, on the dashboard or the rear shelf, rather than in a closed compartment or the boot.
- If the device supports an external antenna, that's the most effective way to extend range - some people mount an antenna on the roof.
- A device by one car's window talking to a device by another car's window works far better than two devices both deep inside their cars.
The limits while the whole convoy is moving
As with motorcycles, while the whole convoy is moving there's no fixed repeater in between. The network is just the devices in the cars. Ordinary radios don't relay for each other, so if the convoy spreads out too far, the two ends can lose direct contact - unless a radio in a car in the middle is switched to Companion Repeater mode (supported hardware and frequencies only, and it uses more battery). The practical approach is to keep the convoy from spreading out too much, and rely on the stop plan for the times you lose contact. If you stop somewhere for a long break and want to cover a wide area around it, that's when it makes sense to place a repeater, or a radio in Companion Repeater mode, high up as a temporary anchor - see Do You Need a LoRa Mesh Repeater?
Cellular where you have it, satellite where it's really remote
When there's signal, internet location-sharing apps work well - use
them for most of the route. The guide
Does Life360 Work Without Signal?
explains exactly where they stop. A LoRa layer fills the no-signal
stretch between cars. If the route crosses a desert, a remote
mountain area, or roads where a breakdown could leave you stuck for
hours with nobody passing, a satellite messenger is a separate layer
worth having for the ability to call for rescue.
In short
Keeping a convoy connected through no-coverage areas combines three
things: a clear route and stop plan, internet apps while there's
signal, and a LoRa layer for messaging and location between cars with
no signal - placing the device near a window or using an external
antenna to make up for the metal body. For genuinely remote routes,
add a satellite messenger.
Getting Started and the
devices guide help you choose hardware and
set up a team.