How LoRa GPS Tracking Works

The short answer

A LoRa GPS tracker does two jobs. Its GPS receiver works out its position from satellites, which needs no network at all. Its LoRa radio then carries that position a long way using very little power, to another LoRa radio that you carry. With Nelos, your phone - paired to your radio over Bluetooth - asks the tracker for its position and shows the reply on an offline map. There's no SIM, no cell tower and no server in between, which is why it works off-grid. The trade-offs are range, which depends on terrain, and update speed, which is measured in seconds to minutes rather than continuously.

The pieces

1. The tracker - a small battery-powered device with GPS and a LoRa radio, on a collar, in a backpack or on a bike. It has no screen and doesn't need a phone.
2. LoRa - short for "long range". A radio technique that trades data speed for sensitivity, so small messages can be heard far away at low power. It uses licence-free radio bands that differ by region, such as 868 MHz in Europe and 915 MHz in North America.
3. MeshCore - the open-source firmware running on the tracker and the radios. It decides how messages are addressed, forwarded by repeaters and answered. Nelos speaks MeshCore, which is why trackers need MeshCore firmware to work with it. (See what is MeshCore?)
4. Your radio - a compatible LoRa device you carry, paired to your phone over Bluetooth.
5. Nelos - the app that sends location requests, draws trackers on an offline map, checks Safe Zones and keeps the history on your phone.

Requested, not streamed

A cellular tracker can upload its position every few seconds because a mobile network has plenty of capacity. A LoRa channel is very different:

• Each message takes time on air. At the long-range settings that make LoRa useful, a single small packet can occupy the channel for a large fraction of a second or more.
• The channel is shared. Every radio in range - your group's, and possibly other people's - takes turns on the same frequency.
• Rules limit transmitting. In some regions, including much of Europe, radios may only transmit for a small share of the time on these bands.
• Batteries are small. Transmitting is what drains a tracker most.

So Nelos doesn't have trackers broadcast constantly. Your phone asks, through your radio, and the tracker answers with its latest position and battery level:

• Automatically every few minutes, also with the screen off when background connection is on.
• On demand with Refresh.
• In Find Mode much more often, for a limited time - frequent location updates during a search, at the cost of more tracker battery.
• Not at all while tracking is paused, which saves battery; Refresh still works.

This is what "real-time" realistically means without a cell network: a fresh position whenever you ask, within range - not a second-by-second line on the map.

How fresh is the position?

While a tracker can see the sky, its GPS keeps an up-to-date fix, so each answer reflects where it is now. Indoors, under dense cover or in a vehicle, the GPS may lose its fix. The tracker still answers over LoRa, but repeats its last good position. Nelos shows how old the last position is, so you can tell the difference between "it's here now" and "it was last here".

Accuracy is that of ordinary GPS: usually a few metres under open sky, worse between buildings, in canyons and under thick trees.

What decides range

Nobody can honestly promise a LoRa range. The same pair of devices can reach across a whole valley from a hilltop and only a few streets in a dense town. What matters most:

• Line of sight. Hills, buildings and the ground itself block the signal; trees, wet foliage and people weaken it.
• Height. Raising either radio helps more than almost anything else. A tracker on a dog's collar sits close to the ground, which costs range.
• Antennas and hardware. Small built-in antennas trade range for size.
• Radio settings and region. Frequency, power limits and the settings your network uses all play a part.
• Repeaters. A repeater in a high spot receives messages and forwards them, so two devices that can't hear each other can still connect through it.

Ordinary radios and trackers don't forward messages for other devices by default. Repeaters do, and some compatible radios and trackers can be switched to relay for nearby devices too, using more battery. If you keep returning to the same area, a well-placed repeater is usually the biggest single improvement - see do you need a LoRa mesh repeater?

Safe Zones: checked on your phone

A Safe Zone is a circle - 100 m to 2 km across - that you draw around a place like a campsite or a cabin and assign to one or more trackers. The tracker doesn't know about it. Each time a new position arrives, Nelos on your phone compares it with the zone. When a tracker has clearly left - Nelos waits for a second, confirming position to avoid false alarms from GPS jitter - you get a notification, and another when it returns. In practice the alert usually arrives within a few minutes of the crossing, and only while your radio is connected and in range of the tracker.

Setting up a tracker

With your own radio connected, you add a tracker in Nelos while it's close to your phone. Nelos configures it over Bluetooth to use your radio's frequency settings, so the two can hear each other. If you later change your radio's country or frequency, add the tracker again. Trackers show up for your team on the shared map; the free plan includes one tracker per team.

Where locations go

Location requests and answers travel over the air between your radios. Nelos needs no account and doesn't send tracker positions to a cloud service; the history of positions received is stored only on your phone. Like any radio signal, LoRa transmissions can be received by other equipment in range, so treat it as a tool for your group's coordination, not a secure vault.

LoRa tracking compared

• vs cellular trackers: cellular reaches you from anywhere with coverage, usually with a subscription; LoRa works without coverage but only within radio range.
• vs Bluetooth tags such as AirTag: tags rely on passers-by; LoRa lets you ask the tracker directly. See AirTag vs GPS tracker.
• vs satellite: satellite works almost anywhere and can reach rescue services, usually with a subscription; LoRa keeps a local group connected at no running cost. See LoRa mesh vs satellite messenger.

Where it fits

LoRa GPS tracking shines when the people and things you track stay within a few hills of you: a dog around camp or on the trail, children at a campsite or festival, a hiking group spread along a route. For a ready-made tracker, see the SenseCAP T1000-E or the other compatible trackers.