Meshtastic

Overview

Meshtastic is an open source, low bandwidth mesh network that runs on 933MHz in the U.S. It runs on LoRa radio technology which is very low power, line of sight. Nodes can broadcast for miles if you are high on a hill. In an urban, flat area you might get 0.25 miles. But the power of the mesh is that if just one node can hear your message, then it can be relayed on to others.

Some people use these nodes when they are out camping in the wilderness without any cell phone service. The nodes automatically repeat messages and share their GPS location. It's a great way for a team to stay in touch.

Of course if you are the only person in your area running a Meshtastic node, then you won't have anyone to chat with. If you want to join a local mesh then you should web search for a group of enthusiasts in your area. Often an area will use radio settings that are different from the defaults, so you need to know what they are. For example, in the San Francisco Bay Area there is an active group names Bay Mesh. They use Discord to help people grow the mesh.

You can buy a node for as little as $25. The node pairs with your phone over Bluetooth and you control it via the Meshtastic app. Once you have your node running you can send text messages to other nodes, or send a message to the "general" channel. Channels are encrypted but the General channel has a default encryption key of AQ== so everyone can read those messages.

You can read up on this fascinating technology at the Meshtastic web site.

Why this page?

While the documentation is good, it feels like a lot is left unsaid. This page holds tips, tricks, and just bits of knowledge that we have come across in bringing up our own nodes into the BayMesh. Hopefully we'll get this knowledge into the official docs, but that can take a while. This page can be updated on the spur of the moment.

Radio Things

Bay Mesh has some good hardware recommendations.

We have personally used the Heltec V3. It is small and simple to use. It comes with a small whip antenna. When we upgraded with this inexpensive antenna our connectivity went way up.

Many radios run at 125 milliwatt. However, some run at 1 watt which is 8 times the transmit power! We are waiting to receive our B&Q Station G2 to see how much this boosts our experience.

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! Always line of sight.

Configuration

The default is "Client". In this mode your node will participate in the mesh by retransmitting messages it receives. (This is a simplification, read the Meshtastic web site for more details.) However, this can clog up the mesh. Unless you are building your own network in some remote wilderness, your nodes should always be configured as "Client Mute", or "Client Hidden". NEVER configure as "Repeater" or "Router" until you know your local mesh needs that.

One exception - Suppose you have several devices in your home / building. In this case you could have one node put up high, maybe in the attic or on the roof, set to "Client" while all your other nodes are "Client Mute". This way your mute node messages will get picked up by your roof top node and it will send them on to further nodes.

Channels

The Meshtastic documentation uses the term "Channel" when discussing radio presets. This is confusing. A Channel in Meshtastic is a communication mesh on top of the radio mesh. Each channel has a name and an encryption key. While nodes in the mesh will pass on channel messages, they cannot read the contents. Only nodes that know the channel name and encryption key can read the messages sent on that channel.

Channels have other control attributes, such as whether to share exact position with other nodes in that channel.

Control

Depending on your hardware, you can communicate and control the node through a serial cable, Bluetooth, or over WiFi.

Bluetooth

The simplest way to configure and communicate through your node is with the smart phone Meshtastic app. You pair the node with your phone over Bluetooth and then can see data from the node. There are also Mac and Windows apps that work to some degree - I've found them a bit flakey.

While a node can be paired with several devices, it can only be connected to one at a time. If you connect to a node with your phone and then go to the laptop app you won't see the node there. You need to disconnect the phone from the node before you can see it in the laptop app - or with another phone.

Sometimes things have become pretty confused and we had to "forget" the node on our Bluetooth devices to get it all working again.

Serial

If you run the laptop app you can connect a serial cable to the node. This seems pretty stable. However, you MUST use a cable that supports data. A lot of cheap USB cables are power-only and this can be very frustrating. If it isn't working, check the cable.

WiFi

Some nodes support WiFi. Often when you enable WiFi it disables Bluetooth. WiFi REQUIRES an SSID on 2.4GHz that is NOT SHARED with a 5GHz network. For example, many home WiFi networks use the same SSID for 2.4 and 5 bands. The access point then "steers" devices to the correct band. This confuses the node and you'll have intermittent success. Find a way to have an SSID for just the 2.4GHz WiFi band and you'll see things work.

When on WiFi you can use a browser to connect to the node through the Meshtastic client. I've found that works, but is confusing. If you get stuck, refresh the page and start again.

Another excellent choice is MeshSense software. This open source solution connects to nodes and gives you great insight into what's going on. It is not good for having text conversations, that is best done in the phone app.

Apple iPhone App

Each node keeps a Node DB with information on other nodes it has seen. This is displayed as a list and a map in the app.

A node can only be connected to one device at a time. When you disconnect from a node the info remains in the app for you to see. When you next connect to a "new" node with the app it will forget everything from the previous node and gather the node db from the current node.

In the node map, pulsing nodes are ones that have been seen "recently", whatever that means.

In the node map, a halo around a node indicates that the node is not sharing precise GPS location. The node is just "somewhere inside that halo".

Position Info

There are several ways to control how much positional information is shared. First, you can configure your node to not share position information, then nothing gets out. Second, if your device does not have its own GPS unit, then it gets the GPS position from your phone when you are connected. On an iPhone you can choose to share "precise location" or not. If you don't share precise location, then iOS takes care of fuzzing your location. Next, Meshtastic nodes have a position fuzzing function as well. You can choose to fuzz your location from 150 feet miles to 14 miles.

Position sharing can also vary by Channel. You can choose to have the node not fuzz location on a particular channel. Of course, a node without GPS cannot report position any more accurately than what is provided by iOS; the errors build on each other.

Position Precision documentation

LoRa Details

Meshtastic runs over LoRa. For those familiar with LoRa you might wonder what settings are used. Meshtastic allows any of the LoRa parameters, but also supplies a number of "presets". This is important because radios must use the same LoRa settings (e.g. network id, bandwidth, spreading factor) to be able to communicate. For example, if some nodes use a spreading factor of 7 and others use 9, they will not communicate; you will have two meshes. There are a few exceptions.

Coding Rate does not affect the ability to communicate. A node in a noisy environment could choose to use a lower coding rate and still participate in the network. The lower coding rate would only affect communication to the first hop. Lower coding rate will make the messages take more air time, thus increasing congestion.

We do not know if preamble length affects the mesh.