Mesh Networks

There are two open source mesh networks we have experience with: Meshtastic and MeshCore. They both use LoRa technology. LoRa radio technology is low power (1 watt or less) and long range (miles) and line-of-sight. It is also very slow - text messages, not images; certainly not voice. (An explanation of LoRa technology.)

Both meshes run on the same inexpensive hardware. Both run without any reliance on the internet. The difference is in architecture.

Meshtastic is the older network. Meshtastic used "controlled flooding" protocol. Every client in a Meshtastic network can retransmit messages it receives from other nodes. This makes the network immediately resilient. 100 people hiking in the woods can use Meshtastic nodes to keep in touch. It is a fire-and-forget network; if your node is not connected when a message comes by, you miss it.

MeshCore has three kinds of nodes: companion, repeater, room-server. All three will run on the same hardware platforms. A companion node is one you carry with you - a leaf node. Companion nodes do NOT repeat messages. A repeater node, well, repeats messages. That's all it does. A MeshCore mesh requires repeaters to be in positions where they can communicate with other repeaters to spread out messages they receive from companions. MeshCore's room-server has a special task - it hosts an access controlled chat room. Companions can log-in to a room-server and leave messages for others to read.

The same hardware devices support Meshtastic and MeshCore.

Because Meshtastic devices are both client and repeater, people often carry them around and the mesh is constantly reforming. This is great when you are out in the wilds. When you are in a dense urban area all the messages advertising nodes can clog the mesh.

MeshCore repeaters are dedicated devices so they tend to stay in one place. This makes the MC mesh more stable topologically. A reply to a message that goes from router x to y to z can use the return path of z to y to x. There is no need to flood every message. This keeps utilization lower.

Radio Things

Bay Mesh has some good hardware recommendations.

Height above ground will dramatically improve your experience. The higher the better. If you drive to the top of a hill your signal will propagate much further. Like A LOT further. In one experiment we got good reception 1/4 mile down the block in an urban setting; the same devices with one on a hill worked at 3 miles! Nothing beats a high placement with clear line of sight.

Line of sight planning tools

• The official Site Planner shows how far your radio will reach
• Move two pins and see what's between them
• Pick a location and see the horizon view
• Give it your location and see the peaks

The cable between your node and the antenna makes a difference. Sometimes you might want the antenna a ways away from your node. Then cable loss can be a big factor and depend on the type of cable. KMR 240 would be fine under 5-10 feet. KMR400 or KRM600 is better and also allows you to go 10-30 feet. It’s usually easier to just put the radio on the pole close to the antenna with a long power or network cable.

Adapters also introduce signal loss. Try to avoid them.

Some antennas have a built in right-angle joint. It seems convenient but in testing several of these we found that while straight they had a SWR of almost 1:1, when in right-angle position the SWR was 3:1 - yikes!

If you have a node that can run high power, like the Station G2, then you can up the RF output to compensate for antenna configuration. What if you have a small unit like a Heltec V3? You might wonder which is better:

• a well tuned 2.5dBi whip antenna with a short cable
• a nice 6dBi antenna with two short cables and an adapter to connect them

If you figure this out, let us know!

If you are in a noisy area, then a well tuned RF filter can boost your signal reception dramatically. They are pricey.