If you want to help build a more powerful and robust goTenna Mesh network, you should consider setting up a stationary, always-on, relay with backup power and internet connectivity. Sounds like a complicated process, but its actually quite simple! Since goTenna Mesh devices are sold in packs of two, the vast majority of owners will have at least one unit to spare which can be setup as a fixed relay. There are a number of motivations for doing this: First, in a grid-down scenario, neighborhoods and communities will have an immediate backup communications network to rely on. GoTenna Mesh devices each act as individual repeaters, silently retransmitting and routing messages from node-to-node, up to 6 times. This means each stationary relay helps build a more robust network as it extends the reach of the network, allowing messages be delivered with higher reliability. Next, goTenna Mesh users will have the ability to send offline (outgoing) SMS messages to family and loved-ones in locations that still have cellular connectivity. This is possible using the goTenna Plus feature set, which will be discussed later in the article. Another key motivation for setting up a fixed goTenna relay with internet connectivity is you will be helping support and facilitate Bitcoin transactions via TxTenna - providing a censorship-resistant method for fellow users to send and receive payments, in a completely offline manner. We will elaborate on TxTenna specifically in an upcoming blog post - sharing our own experiences and tips on how to use the app.
To get started, here is the current map of where goTenna Mesh units are deployed:
Pretty impressive! Now let's click on the layer icon and filter for Powered Stationary Relay Nodes only:
We can see there are significantly less Powered Stationary Relay Nodes, but still a decent amount. Now, let's review the overall numbers for all nodes:
So less than 10% of all nodes are Powered Stationary Relay Nodes. These overall numbers are likely substantially under-reported, as the hit-rate on users that self-report their goTenna locations is likely quite low. According to our estimates, total mobile nodes are realistically 10x the reported numbers, if not higher. Even so, the number of Powered Stationary Relay Nodes has plenty of room for growth, and that is what we are interested in today. Here is a good representation of a node cluster that could benefit substantially by converting all of their mobile nodes to fixed powered nodes:
Each nearest neighbor node is located between 0.3 to 0.7 miles apart, so messages will be able to hop from any endpoint and be delivered reliably to their intended recipient. Shout messages allow anyone in the network to send an SOS or tap into hyperlocal knowledge shared between fellow neighbors. In this example, we've highlighted the Hidden Meadows community, located in northeast San Diego - an area that is prone to wildfires.
The simplest way to create a Powered Stationary Relay Node is to take a spare goTenna Mesh, plug it into an outlet with 5V power brick and keep it powered on at all times. Set the unit in relay mode by quickly pressing the power button 3 times in succession, wait for the LED to go solid white, and then press the power button 3 more times to complete. A quick tap on the power button will show 3 flashes on the LED to confirm relay mode. Even better, keep the goTenna Mesh unit paired to an old smartphone or tablet, assign the goTenna a random GID, and keep the smartphone or tablet in airplane mode but with WiFi enabled to your home WiFi access point. GoTenna Mesh units always relay messages, even if they are in paired mode. If you want to take your Powered Stationary Relay node to the next level, place it at a high point in your home, such as upstairs, next to a window and connect it to an always-on battery pack, such as the Voltaic Systems V44, V50, V75, or V88. Now you've got a relay with redundant power supply in case the power grid goes down. These battery pack units will keep your goTenna Mesh and smartphone powered for multiple days, if not weeks depending on which model you select. An additional recommendation is to place your goTenna Mesh in a vertical orientation for best signal propagation, and an easy way to do this is to use a simple 3D printable tripod, like this one available on Thingverse. We had 5 of these units printed through Treatstock, and they cost about $8-10 each. If you already have a 3D printer, even better - print it yourself!
Now the final step is to report your node location on the goTenna Network Map. Provide a description of the relay node capabilities and an estimated coverage range. Include your goTenna Mesh random GID so the unit can be pinged by fellow users. If you're concerned about privacy, consider fuzzing the location by a few hundred feet, whatever you feel comfortable with - just try to convey a general sense of where the coverage will be available. Here is how our Powered Stationary node looks on the map:
So, let's get back to the concept of sending offline (outgoing) messages that will show up as SMS messages on your friends smartphone. When you first install the goTenna app, it asks if you would like to enable the goTenna Plus trial. The Plus feature suite includes the ability to download offline topographic maps, access the SMS relay function, get trip statistics, and auto-share your location with others. The Plus trial includes a 30-day trial period and costs $9.99/year to subscribe. This is a nice add-on to goTenna Mesh and we have been active subscribers for a couple years now.
One quick workaround if you need to use the Plus feature suite and you're not interested in paying the subscription fee is to delete your goTenna Mesh app and reload. Now you've got another 30 days to use the Plus feature set. The main drawback with doing this is you lose your message history, contacts, and downloaded maps. Also, its important to note that if you are trying to use the SMS relay feature and you have installed the goTenna app offline, (via sideloaded APK) you will need to allow your phone to briefly access the internet via WiFi or cellular network so you can sync with the goTenna network relay server. The main point here is to make sure you set this up in advance of when you're expecting to go offline for a long duration.
Now, when you are ready to send an offline goTenna message to SMS, go to chats, input your contact's phone number (with leading +1 in US or proper country code elsewhere) and attempt to send your message. After the message times out, long press on it and you will see an option to send via SMS Relay. If you click on that option, the message will now attempt to send via a nearby goTenna Mesh device that has internet connectivity. If the message is successfully sent, you will see a green confirmation check-mark and a confirmation message stating "Sent via network relay". You can rest assured your intended recipient will receive the incoming SMS within a minute or two. One thing to bear in mind is the recipient will not be able to respond to you, as the message has no way to traverse through the cell network back to your goTenna. Also keep in mind that the message may not be completely secure as it travels through a third party's platform, so just use caution with the messages you send. At Tourmaline Wireless, we are creating a SMS Gateway accessory product that will allow you to send messages back and forth, from offline goTenna Mesh endpoints using a cellular (and satellite) connection. This will effectively allow geographically separated goTenna networks to connect to one another on a global scale. We hope to share additional details soon on the product development of this gateway. Here are a few screenshots that depict the SMS relay sequence. Just remember, you need to have an internet-connected goTenna Mesh nearby to relay your message, otherwise this won't work.
Well, that's it for now... lots more to cover, including the portion on TxTenna and offline Bitcoin transactions, but we'll save that for a future post. Thanks for reading and drop us a comment below if you found this useful or have any questions. -TW