Meshtastic: An “appliance” operator’s foray into off-grid messaging

While some may consider Meshtastic to be their “solarpunk dream” (1) other views include the old trope that it’s not amateur radio but still “.. interesting stuff done with radio, worthy of interest.” (2). More formally Meshtastic is a platform agnostic software application that is an “..open source, off-grid, decentralized, mesh network built to run on affordable, low-power devices.” (3). The Meshtastic software can be configured to allow for amateur radio application with slightly increased power levels.

The radios automatically rebroadcast messages they receive in order to create a mesh network so that everyone in a group or "mesh" can receive messages - even from the furthest member. Depending on settings used, the Meshtastic mesh can sustain up to 80 device nodes.

While enthusiasts have used this technology at major off-grid events such as Burning Man and Glastonbury festivals and the tech of keen interest among "preppers", there is also interest among amateur radio operators in the Ottawa Valley, exploring alternate communications technologies beyond cellular and satellite communications.

Among those involved are some members of the Almonte Amateur Radio Club (AARC) who have been promoting interest in a local amateur radio mesh network on 433MHz. Currently there are 8-12 hams operating in a mesh network as part of their amateur radio stations that spans generally from Ottawa to Arnprior. The AARC has also established a group list which the Meshtastic software identifies via a QR code. This might be potentially available for other clubs wishing to establish their own club group lists.

The device that I purchased was the Lilygo T-Beam (V1.1 ESP32 LoRa Wireless Module) from Lilygo for around $50 CDN. While not strictly necessary to run the device I also purchased a specialized 3.7V ICR18650 2600mAh Pkcell battery from a local Total Battery outlet for around $18 CDN. As a note on the battery, I bought the button top style, and a better better recommendation was made from Cristian VA3CTQ and Jeff VE3EFF to go with the flat end version of 18650, which fits better in the battery holder attached to the back of the T-Beam board.

Completing my set-up I have about 75 feet of LMR-195 to a Comet GP-9 at about 30 feet above the ground. To continue with the use of my GP-9 antenna for VHF I tried using a Comet VHF/ UHF duplexer, but wasn't able to make any successful text message contacts with this arrangement. Without the dulexer in-line I found a greater chance of making successful contacts as indicated by the message status symbols that the Meshtastic app. provided the operator.

I installed the Android version of the Meshtastic software which provided a range of views that the operator can use to "see" other node operators on the network. An example of one of these screens along with an explanation on what some of the metrics indicate is included on the next page.

Jeff VE3EFF provided an explanation that:

Chanutil % is all packets on the channel for the last minute as a percentage, and
Airutil % is the total duty cycle of device transmissions over the last hour.

Otherwise you can see call signs, lat / long coordinates, a battery strength indication as well as what I take to be signal strength indicators (rssi and snr-) - but I could be wrong on that!

As an "appliance" operator attempting to learn a little more about how I could improve the performance of my mesh device I asked others on the network to provide descriptions and some photos of their set-ups and what has worked for them. Some of these descriptions and pictures are captured on the following pages.

VA3CTQ Cristian: As each LoRa device is a node in the Meshtastic network, they act both as a transmitter and a repeater. With a couple of LoRa nodes (devices) nearby (7-9 km), this helps sending and receiving messages from anywhere in the network. Living in rural area also helps with generally lower QRM than urban environments. In general terms the number of nodes in the network, and the space between those nodes determine the speed and the quality of the signal inside the network.

VA3CTQ’s set-up includes:

Tablet connected to the LILYGO® TTGO T-Beam LoRa device using Bluetooth.
T-Beam LoRa device with Meshtastic software installed, connected to a Comet GP-3 VHF/UHF antenna using ~6m (20ft) of RG-213/U coaxial cable.
The antenna is placed outside of the house, 4m (~13ft) above the ground.

VE3HOA Phil: The "VE3HOZ" T-beam is connected to a bi-directional 2 watt amplifier unit which also has a built-in receive pre-amp. The output of that is fed through a few Sinclair filter cans to reduce local noise and also to reject Phil's HOZ DMR repeater (which can overwhelm the T-beam receiver). This is fed to an external vertical antenna on his tower. This is configured as a LoRa "repeater" to reduce the broadcasts it makes.

The other picture below is a T-echo unit set up as "VE3HOA". It is a little self contained unit with the same capabilities as the T-beam...but comes packaged in a case and has a small 850 ma/h rechargeable battery with a usb charging port.

Phil connects to it via bluetooth using the Meshtastic app on his Android cellphone. That is what he uses for his meshtastic daily ops. It's set for very low power since it only needs to communicate with his HOZ T-beam repeater. Phil can easily move the T-echo around the house as necessary to maintain the bluetooth connection.

VE3EFF Jeff: Prior to the advent of Starlink Jeff VE3EFF lacked reliable cellphone and internet connections which is what led him to explore the utility a 433Mhz Lora T-beam with some of the members of the Almonte Amateur Radio Club.

Jeff VE3EFF already had a dual band fibreglass vertical he used for VHF and decided to duplex a t-beam mesh unit to the UHF side of the vertical. He also used 30ft of LMR400 to reduce line loss.

Jeff VE3EFF's set-up include:

T-Beam Board – running about 100mw in Licensed amateur mode.
A 18650 3.7v 2000-3000mah flat top battery (flat top fits more easily into the t-beam battery carrier).
433 MHz bidirectional amplifier provides about 1 watt of power and some receive gain. Jeff Ve3EFF advises that while this may be fine in a rural area that in an urban area the receiver may be overloaded with an rx amplifier as he suspects the T-Beam has very little front end filtering.

For an urban area a 433Mhz band pass filter in front of the amp is advisable as it passes 75Mhz 400-475Mhz and reduces all the other frequency traffic.

For a 5V power supply cut from an old micro USB cable and used it for the t-beam from the power supply kit. The amplifier connects to the 5v output. If not using the amplifier, then all you really need is a cheap USB 12v to 5v buck converter to charge the t-beam, or an old cellphone charger.

An external GPS antenna is also recommended since the small antenna supplied with the t-beam is not that sensitive.

An external Bluetooth (BT)/WiFi antenna for better BT coverage to Jeff's phone around the house, although typically the antenna on board is fine for general use.
Finally, for the complete unit in its case - see below.

REFERENCES

Tyler Cipriani’s Meshtastic review – see https://tylercipriani.com/blog/2022/07/31/meshtastic-a-review/
Richard G7LEE as written a great piece on Meshtastic for the Isle of Avalon Amateur Radio Club – see https://www.avalonarc.org.uk/2022/12-07-trying-out-meshtastic.html
For more information on Meshtastic see https://meshtastic.org/
For more technical information on the hardware in use by local Ottawa Valley operators: https://www.lilygo.cc/products/t-beam-v1-1-esp32-lora-module?variant=42204034891957

Appears in: Rambler Vol 65 Issue 9, May 2023