I recently started exploring Meshtastic for off grid texting. In particular, what frequencies does it operate on? How far is the range? Who is currently using it and for what?

This post is not intended to be a complete “how to” for Meshtastic. This post touches on a very high level overview of the platform and my observations after only a few months of getting started with it.

LoRa – Long Range Wireless

Meshtastic is a communication layer which utilizes LoRa, or Long Range Wireless. LoRa utilizes Chirp Spread Spectrum and in the United States runs at 915 MHz as the center frequency which is designated as an ISM (Industrial Scientific and Medicine) allocation. This designation is for unlicensed use (within the parameters of the FCC and ITU of course).

Note that this overlaps with the 33cm amateur band, which we are secondary users of. More on this later.

Long range wireless is a subjective description. For amateur radio operators, “long range” means around the world. In other circles, it might mean a few miles. This makes sense if we consider other non licensed RF allocations such as Bluetooth and WiFi. A few miles is long range compared to these references. In my testing, I have seen at least a one to two mile range with these low power LoRa devices. With height and a decent antenna, I’ve heard nodes up to 12-15 miles away.

LoRa utilizes low power and entire LoRa chipsets have become popular, making incorporating this RF protocol into a product very easy and very inexpensive. It has also resulted in experimenters boards being readily available.

LoRa can be used to send and receive measurements and readings from instruments such as temperature, location, speed, or just about anything a typical IoT device would send or receive.

Experimenter Boards

The LoRa experimenter boards come with the radio, an antenna connector, power management (usually from a USB input), and pinouts from the CPU for wiring up to a breadboard or another PCB. Some will include an OLED screen, WiFi, Bluetooth, charge controller, and/or a GPS module.

These boards have become effectively a complete and portable LoRa platform with little to no real assembly needed. Unlike typical “kits”, these require mechanical assembly at most, such as fitting into a case or connecting an antenna and a battery.

Meshtastic on LoRa

Meshtastic is a layer on top of LoRa – a complete software meshing platform which utilizes LoRa for the RF communication.

It’s important to note that the Meshtastic software which runs on the LoRa boards supports specific chipsets. Not every chipset is supported and many of these boards are sold with specific mention of support for Meshtastic. Some are pre-flashed with Meshtastic, others are not and can easily be flashed.

When purchasing a board, be sure it is a LoRa RF board and be sure it is listed as compatible with Meshtastic.

Also be sure to purchase a board that is on the correct band for your region. For example, in the United States, this is 915 MHz (or another band such as 70cm, where permitted). You will want to be sure that the band you choose is not only allowed in your region but also where other Meshtastic users would be. For example, at this time, most Meshtastic devices in the United States are on the 33cm band (915 MHz), and not 70cm.

Also be sure the antenna you attach is also designed for the band the RF board operates on. Otherwise you will not get the best range possible. Worst case you can damage the transmitter. Many of these boards can be powered off or shut down by pressing and holding one of the buttons. This should be done (or remove the power source) before disconnecting the antenna. Of course, never power up one of these devices without an antenna attached.

I have found that it is best to open the LoRa settings and disable transmit. That ensures that the device will not transmit until you are ready (with the antenna attached).

What can Meshtastic Do?

Meshtastic offers node to node text messaging and “group” messaging. It has the ability to “mesh” or form small networks of nodes to relay messages between them. Simply being within range of other nodes, they form a smart mesh for directed or group messaging.

Since this messaging and mesh protocol sits on top of LoRa, this is entirely off grid. It requires no internet connection nor cellular connection (unless you enable MQTT).

The protocol supports “hopping” or relaying so that a node in between two other nodes can carry the messages between other nearby nodes. This is similar in concept to digipeating for example with APRS. Meshtastic relies on this relaying or repeating for broader messaging networks.

If you have a few nodes around town, each within range of at least one other node, town or city wide communication is easily possible.

There are practical limits to how many hops should be supported when getting a message from one node to another. This setting is named “Hop Limit” and is set to 3 as a default.

A Terminal is Required

Unless your Meshtastic device has a built in screen and keyboard, you will need a “terminal” to not only configure your node, but also to view and send messages.

The most common way to connect to and interface with your node is with a mobile device over Bluetooth with the Meshtastic app. You pair your mobile device with the node over Bluetooth and then use the app to configure the node and to view and send messages.

It is also possible to perform these operations over a serial interface, if your device supports it, which is also how firmware is updated. This serial device is accessible over the USB port on the board.

There is also a web based interface you can use if you have paired your node to a computer via Bluetooth, connected it via USB (using the serial connection) for example, or if you enable the WiFi/Network feature. Note that on most boards I have tried, when you enable WiFi, Bluetooth is disabled since they share the same interface and antenna on the board.

For home or fixed nodes, enabling WiFi (if your board supports WiFi) for the interface is most convenient for interfacing with the node, since Bluetooth has a much more limited range. WiFi would allow the device to sit on your network, and make it accessible anywhere you are in the house or building, even when remote if you have VPN access into your network.

For portable nodes, Bluetooth is the most convenient option for connecting to the node.

The most convenient option would be a device with not only the LoRa board but a keyboard and screen. However, since most of us carry a mobile device in our pockets, a smaller LoRa board inside a small case fits in the pocket just as easily.

The Meshtastic devices will store incoming messages in its own queue and forward them even if no terminal device is connected to it, which means they are autonomous in that respect. When you come back into range or connect to the node again, those messages will be there to view.

This is an important point to make because it means you can place these nodes in strategic places to establish a coverage area and you do not need to connect anything to them in order for them to mesh once you configure them.

To Encrypt or Not Encrypt

Licensed amateurs can use more power on the 33cm band than the available power levels on LoRa radios. For example, if you wish to use a device which has 10 watts of power, you can, provided you are licensed. However, if you use the licensed mode of operation, then your device will ID every 10 minutes and will have encryption disabled.

Most of these LoRa boards are a few milliwatts, perhaps 100 at most. Licensed mode would not be required unless you operating a device with more than 1 watt EIRP.

One thing to consider is who you will want to communicate with – all parties need to use the same encryption keys in order to exchange messages. Or, all parties have to have encryption disabled.

It’s important to note that all of the “squawks” or node info that is beaconed occurs on the primary channel, which means if you do not use the same encryption key, you will not “see” those packets.

When I first set up my nodes, I disabled encryption and enabled the licensed operator mode. I saw no nodes other than mine after a week of testing.

As soon as I reset my nodes to the default mode and encryption key, “AA==“, I immediately began seeing other nodes.

Range Test Results

My first range test was with a RAK board which has a solar panel attached and is inside a weatherproof case. This device was premade and was ready to use when delivered.

There is a 3.7 volt 18650 battery inside the case and it is charged by a 9 volt (peak) solar panel. The RAK board has a charge controller.

I placed the device outside. Since my QTH elevation is about 325ft, I have a clear line of sight to east toward NYC.

My second node was a T-Beam, connected to a 915 MHz magnetic mount antenna in the car. I drove around and would occasionally send a direct message to the QTH node and wait for acknowledgement of the test message.

My results varied quite a bit, and were limited by objects in between my QTH node and the car. The results were surprising, given the low power output by these devices. I was able to easily get several miles away with acknowledged messages. However, direction and a clear path were critical. The QTH is on a hill and my car travels were mostly down the hill in the valley or on the other side of the valley during my testing.

Location and Privacy

These devices can beacon location. They can either be set to a fixed location or use a GPS source. Some devices have a built in GPS module. Your mobile device GPS can also be pushed to the node for its positioning source.

Enabling granular position information comes with some drawbacks, mainly privacy. You can disable location completely within the device and software, or change the location beaconing to a more general (less granular) location.

MQTT

MQTT is an IP bridge that allows nodes to be bridged over an IP network such as the internet. In my experimentation, I had this disabled. This is because I am interested in off grid communication primarily, I did not want MQTT nodes appearing, and wanted to see only direct or meshed RF devices.

Node Maps

The Meshtastic app has a map feature to visually plot all nodes you have heard. This includes nodes which are reachable indirectly via the mesh. Of course, this is limited by the number of allowable hops in each nodes settings, which is defaulted to three.

I was quite surprised by the range. My nodes are about 325 ft above sea level at the QTH which helps. Other nodes also help with coverage.

There is a web based map available, which relies on nodes enabling MQTT in order to feed the data into the pool of active node data. Even though I have MQTT disabled, others can have this enabled which forwards the nodes they hear (including mine if in range) into the MQTT database.

Puzzling One-Way Issue

After several weeks of testing and trying to send direct and primary channel messages to nodes “seen” downhill with no acknowledgment, I finally figured out what I suspected was happening.

Some nodes were running more power than these evaluation boards have by themselves. I can hear these nodes since they are running more power, but they cannot hear me. This is because I was running my boards with no power amplifier at all.

The other effect of unbalanced power is another node on the other end of the hill I am located on cannot hear my node and vice-versa. In theory, we should be able to hear each other via the node we both hear down the hill. Because that node down the hill that we both can hear, it does not hear us, and cannot relay for us.

The method I used to determine if a node “hears” me is to send a trace route request. If I receive a reply, then that node hears me. If I do not hear a reply, then that node either does not hear me or does not respond to trace route requests.

Not a single node (other than my own nodes) I heard have ever sent me a reply back to a trace route request. Me hearing them and them not hearing me is indicative of uneven transmit power levels, given the variables in play. Line of sight is there, I used multiple nodes and antenna combinations in my experiments.

Power Amplifiers

If you are a licensed operator, you can transmit up to 10 watts with LoRa on 33-cm spread spectrum. If you are not a licensed operator, your power limit is +30dBm or 1 watt.

There so happens to be quite a few amplifiers for 915 MHz available on Amazon. I use Amazon as the reference here because I have operated on the 33cm band and there are absolutely no commercial transceivers currently on the market in this band specifically for amateur radio anywhere (at the time of this post). I happened to pick up an Alinco DJ-G29 on eBay awhile back for quite a hefty price.

Finding 33cm amplifiers on Amazon is interesting because they are not marketed to amateur radio operators, but they exist because of the gaining popularity of LoRa.

To test my theory of why I was hearing nodes but they were not hearing me, I picked up a 915Mhz 1 watt amplifier on Amazon to test increased transmitting power.

There were far less expensive models on Amazon but my theory of “you get what you pay for” applies here, most likely.

This model is made with an aluminum enclosure and SMA inputs and outputs. It requires 12 VDC via a very small barrel connector on the side. It comes with a power adapter for powering from mains.

It has a variable gain control to adjust the gain given the input signal power level.

I could connect any one of my nodes to the input side of this amplifier for testing. Most importantly, the antenna I connect to the output of this amplifier would determine the level of improvement in transmitting range.

Success

With the addition of the 1 watt amplifier, I was able to get a response from a node down the hill (one suspected of also running with a power amplifier). The trace route request was acknowledged!

Mobile Testing

I put a T-Beam in the car with a mag mount designed for 915 MHz and connected the USB port for recharging. This allowed for the device to work automatically when driving around with automatic recharging of the internal battery.

I did not really see many nodes this way, unless I parked at a high elevation for awhile. I even ran the node on a 6 hour road trip and saw only a single node along the way.

Final Thoughts

Meshtastic is a great platform using LoRa for off-grid texting. This can be helpful recreationally as well as during outages or when out of range of cellular communication.

Assuming the ISM designation is not revoked for the 915 MHz band and these devices in the future, these are great for non-licensed users to use and become active with. And, for those who are licensed amateurs, if the designation is ever revoked, assuming 33cm remains within the amateur radio privileges, amateurs can continue to use the platform, without encryption of course.

Even though there are a few bugs here and there, these will likely get fixed and more features are likely to be added.

I ended up leaving a node with an amplifier connected in an upstairs bedroom for maximum range (without more effort). I occasionally check for new nodes and messages and will likely leave it there for awhile.