Unless you’re a completely isolated loner, communications are going to play a critical role in both short-term and long-term disaster scenarios. Being able to effectively exchange information with family, friends and community members in both short-term as well as long-term disaster scenarios can literally mean the difference between surviving or going the way of The Dodo. There have been dozens of articles on SurvivalBlog about the use of radios for voice communications, and having appropriate radios and communications plans should definitely be considered a critical part of any preparedness plan. However, there’s another form of communications that should be considered to complement radio communications – the ability to exchange text messages without the need for any supporting infrastructure. There are some use cases where texting can provide significant advantages, including:
- Communicating silently if you need to stay quiet
- Reviewing previously received communications
- Secure encrypted communications with minimal risk of being intercepted
- Sharing communications among a large group simultaneously
- Something that works with existing technology like cell phones and with a minimal learning curve (texting)
- Relatively compact with a long battery life
- Something that doesn’t stand out in our current society like a handheld radio would
- You don’t have enough radios for everyone in your extended group
Back in 2016, I found a solution called Gotenna that allowed completely off-grid text communications between mobile phones, using a device you paired with your phone via Bluetooth. I paid around $500 for four of the devices and used them regularly to send text messages among friends and family when hiking in back country, playing paintball in the woods, etc. Unfortunately, a couple of years later after selling thousands of consumer devices the greedy jerks at Gotenna decided to stop supporting the consumer market to focus on lucrative government contracts and essentially ended all support for the devices they’d sold. You could continue using the device on the phone you originally paired it with, but they shut down their registration server so it became impossible to move the device to a new phone, so when you wanted to upgrade or switch phones the devices essentially became worthless. Many people asked Gotenna to at least provide details on the registration protocol so they could set up their own registration servers and continue to use their devices, but to no avail.
Then, around 2020, a bunch of really smart people decided to start developing a similar capability called Meshtastic as an open-source project. Meshtastic is a mesh communications framework that runs on top of a radio protocol called LoRa (Long Range), which is designed to provide low-bandwidth communications over a very long range without any additional supporting infrastructure like cell towers or the Internet. This makes Metastatic an excellent choice for off-grid text communications in both short-term and long-term disaster scenarios.
LoRa
LoRa is the underlying radio communications protocol that Meshtastic runs on top of, so it helps to have a basic understanding of how it works. The official definition of LoRa is ‘a proprietary spread spectrum modulation technique derived from chirp spread spectrum (CSS) technology’, which is pretty much gibberish for the majority of us, but there are a number of valuable features that result from the way LoRa is implemented:
- Very long range – Meshtastic nodes running over LoRa can typically communicate well over a mile in even urban environments, and over many miles in wide open terrain. The record for Meshtastic communications with LoRa is over 200 miles between two mountain tops.
- Very low power consumption – LoRa devices can run for days on a single battery charge and can be powered by solar chargers.
- Interoperability – Any Meshtastic LoRa device can communicate with any other Meshtastic LoRa device (in the same country), regardless of manufacturer.
- Low cost – Chips that implement a LoRa transceiver only cost a few dollars.
The primary limitation of the LoRa is its bandwidth – it’s only designed to send small packets of information, which are limited to around 200 characters, so it can’t be used for things like streaming video or transferring large image files. For those of you who have worked in IT and are familiar with the OSI networking model, LoRa only provides the physical layer (Layer 1) of the network, much like a physical Ethernet cable that connects a computer to a router or switch. It only defines how nodes communicate information at a basic level, not what information is communicated.
Like any radio technology, LoRa operation is limited to specific frequencies, which vary by country. In the US and Canada the designated band is 902 to 928 MHz (typically referred to as ‘915MHz’), while in the EU it’s 863MHz to 870MHz (typically referred to as ‘868MHz’). In most countries the frequency band is designated for Internet of Things (IoT) communications and is unlicensed, so you don’t need special permission to use it. The Meshtastic website has a page that provides country-by-country information on LoRa bands.
Note that when researching Meshtastic you may occasionally come across references to something called LoRaWAN, which is a different networking protocol that runs on top of LoRa radio communications. LoRaWAN is completely different than Meshtastic, but some devices can run either Meshtastic or LoRaWAN (just not at the same time).
Meshtastic Overview
At its core, Meshtastic is a wireless mesh network for exchanging short messages. A mesh network is a network where all of the nodes broadcast messages directly to all of the other nodes to communicate without any kind of central infrastructure. There are three major advantages to a mesh network:
- No complex or expensive supporting infrastructure required (e.g. switches/routers/etc.)
- If a node needs to send a message to another node but the target node is too far away for a direct connection, other nodes that are closer will pass the message along until it reaches the desired target.
- The failure of any single device in the mesh network doesn’t necessarily impact the network’s ability to exchange messages – other nodes can still pass messages along.
The following diagram illustrates what a Meshtastic network might look like:
Every Meshtastic device node has two components – a radio interface chip that implements the LoRa protocol, and a microprocessor (computer) that runs the Meshtastic firmware on top of the radio. The most popular LoRa radio controller chips used in Meshtatsic devices are the Semtech SX126x and LR11xx series, although the LR11xx is a lot newer and only starting to show up in Meshtastic devices. The LR11xx series claims to offer better radio performance.
Regarding microprocessors, there are three families that are currently supported by Meshtatsic devices:
- Nordic Semiconductor nRF52x series
- Lowest power consumption
- Bluetooth but no WiFi built-in
- More expensive
- Fewer devices currently available
- ESP32 series, designed by Espressif Systems and manufactured by TSMC
- Built-in WiFi and Bluetooth
- Better CPU performance
- Higher power consumption
- Generally less expensive
- Lots of devices available
- RP2040, designed by Raspberry Pi Ltd (the same folks that make Raspberry Pi single board computers)
- Moderate power consumption
- Moderate price
- Few devices available
- Similar to other Raspberry Pi devices
Why is knowing the processor details important? Because there are many different ways Meshtastic devices can be configured and used, and understanding pros and cons of the underlying architecture can help you choose the right option. For example, if you plan on providing Meshtastic devices to each member of patrol team that will be out for several days, having devices based on nRF52x processors that can operate for days without needing to be recharged would be your best option. On the other hand, if you want to connect a Meshtastic device to your local WiFi network, having a device based on an ESP32 processor with built-in WiFi is a good choice.
An individual Meshtastic device (or node) typically consists of two pieces of software – the firmware I previously mentioned that runs on the device (node) itself, and a configuration/interface/management user interface app that runs on a phone, PC or web interface. Here’s a picture of the overall architecture:
There’s also a new capability that was recently added called the Meshtastic User Interface (MUI), which is designed to run as part of the firmware directly on Meshtastic devices with a built-in display and full keyboard, eliminating the need to connect to a cell phone or computer.
(To be continued tomorrow, in Part 2.)
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