Long-Range Low-Power Text Messaging / SMS


(Andrew) #1

Throwing this out for ideas, feedback, and help with any development required.

GOALS

Establish a wireless communications network in the area pictured. Primary uses are simple communication, and updates of location for safety, weather, and mechanical issues relating to boat and overland travel.

FEATURES + PRIORITIES

  1. HIGH - Text/SMS messaging between devices
  2. HIGH - GPS Location
  3. HIGH - 2 people with communication devices
  4. MEDIUM - 7ish people with communication devices
  5. MEDIUM - Web or Android and iOS device access
  6. MEDIUM - Relay of real-time location between devices
  7. MEDIUM - Voice calls
  8. MEDIUM - Email
  9. LOW - Internet

PARAMETERS

  1. Super easy for end-users
  2. No paid subscriptions (decentralized)
  3. There is no cell coverage in this area
  4. Low power - There is no electrical grid in this area
  5. Extreme low temperatures - In winter, temperatures reach -40 (C/F), and most batteries perform poorly in this range
  6. Low solar - This is 65°N. In the winter, the sun is at too low an angle to clear the trees in the valley. Some sun reaches the hills, but there is often significant cloud cover in winter months.
  7. Low wind - Similar to solar, the locations on the river valley get low wind. There is wind that gets funneled across the hills, making wind power potentially feasible.

MAP OVERVIEW

The red markers are locations that offer a good representation of locations which would need to receive signal. The blue markers are potential spots to drop repeaters. The black lines and numbers represent the distances between repeaters and the farthest locations on the current spec.

WIDE

WEST

EAST

IDEAS + CONCEPTS

  • LoRa / LoRaWAN - Long-range and low-power radio transmission in the 900mhz band. Relatively inexpensive hardware ($20-$50 ea.). Theoretical range 100+ miles line-of-sight (LOS). Practical range .5-5 miles at same elevation. Performance significantly increased with repeaters at high elevation

Tutorial: LoRa based messenger Project| LoRaWAN

SMS over LoRa: Long distance SMS without 4G

  • The videos above can likely be simplified by using different ESP32 modules. For example: Whereas the above proofs of concept require multiple boards, the TTGO T-Beam has all the necessary components (Bluetooth, LoRA, WiFi, ESP32, 18650 LiPO holder, battery charging) integrated onto one $25 board.

TGO T-Beam // ESP32, GPS, LoRa & Bluetooth

  • goTenna (Mesh, Mesh Plus, Pro) - This project is already existing, and would not require any development on our end to resolve the high-priority goals. They do have a free and open SDK available. On the negative side, they have low (~3.5 star) reviews on Amazon and the Android app. The devices are roughly $70 each. With an annual subscription, these can link out to the external internet, and provide SMS integration with regular phones and tracking maps.
  • FRS / GMRS / Marine radio - These options could handle voice relatively cheaply. Unsure of legality of repeaters on these bands. Generally speaking, these are free and unlicensed bands. Unsure of legality of transmitting tone-based text messages on these bands.
  • HAM radio - The text messaging could be handled via APRS (HAM). The huge negative is that this would require everyone using devices to have a HAM license. Another negative is that all communication must be public, totally unencrypted, and non-commercial.
  • Baofeng UV-5R radios for FRS / GMRS / HAM - Inexpensive radios which can be programmed to work in licensed or unlicensed bands. We already have 2 at camp, and potentially have access to 3 more at no cost. Repeaters can be built with 2 radios. In theory, 2 repeaters (for a total of 4 radios) could be installed, and this could scale uup to any number of users simply by adding 1 radio per user.

Set up a Baofeng UV-5R repeater

  • AREDN - Decentralized network which also can connect to internet. Uses relatively easy to acquire WiFi networking equipment. Works in bands which require HAM license. Can be used for all normal internet protocols for voice, chat, email, media streaming, etc.
  • LibreMesh (or other community WiFi mesh) - Works on standard WiFi access points with custom open source firmware based on OpenWRT/LEDE. Can be used for all normal internet protocols for voice, chat, email, media streaming, etc.

INITIAL THOUGHTS

We already have FRS / GPRS / Marine radio working, but without repeaters at higher elevations, the range is not very useful. It wouldn’t be very difficult to build a couple UV-5R repeaters to provide full coverage in the required area. We would have to look into the legalities of repeaters for the various spectrums not requiring licenses. Also, the relatively high power use of these radios would likely mean that the system would fail in the winter due to freezing batteries.

Adding the simplest LoRa implementation to the radio option in the preceding paragraph may be the simplest and most open/flexible path. The rub here is that it would require significant hardware and software development time and energy. I think this is withing our capabilities, but it may not be “worth it”.

Adding goTenna Mesh devices to the radio option above would be the simplest, but may ultimately be unstable. This would require at least 2 devices to mount as repeaters. The power use may be low enough to work in the winter when batteries begin to fail.

WHAT’S THE ANSWER?


#2

What about solar/wind charged drones that fly the coverage area and deliver messages sneakernet style?

I’ve been looking into this stuff and have been trying to figure out something similar for a while. I finally came to the the conclusion that most current methods bathe an area in possibly harmful radio waves. I’m thinking that a few fast, small drones with low power wifi could cover a pretty big area and work relay race style. The hardware would be easy but the autonomous flight path routing and networking stuff is over my head.

Another idea is to use the water to transmit data between dispersed wifi repeaters with sonar but that might mess with the fish.

I’ve got one of those try not to die headaches going right now but this topic is super interesting to me so I’ll be back with more ideas later.


(Andrew) #3

I can’t see drones or sonar being practical here, or affordable anywhere. Let’s please keep this thread to RF. You’re welcome to start a new thread on drones, pigeons, ravens, notes tied to arrows, and tech for sending data through the 4 feet of ice currently on the river.


(Andrew) #4

Added that it should be “super easy for end-users” to the parameters.


(Andrew) #5

LoRa SX1278 long-distance chat sms pager project

Video of LoRa Chat test
https://youtu.be/H42atKsWvzU


#6

Sorry if text is failing me here again and I’m off base, but there’s no need for the shitty dismissive tone.

Just because you think something’s difficult or impossible, it doesn’t mean that is. A ulf sonar repeater could be very inexpensive to diy, and easily repairable drones are starting to hit landfills daily.

I’ll keep my ideas to my tribe from now on, if I can ever find them…


(Andrew) #7

I was attempting to make light of the impossible line between primitivist fundamentalists who have literally told us to use pigeons versus the idea of flying robots.

So yes, text is failing us. Ironic in a message about text communications.

At the same time, I do think it’s completely reasonable to shift conversations about drones to another thread. We don’t have access to landfills with abundant repairable drones here. You’ve been in previous threads where that sort of limitation has been articulated. I can admit that it is somewhat frustrating when it appears there is a lack of thought put into the challenges at our camp that are not the same as those elsewhere.


(Andrew) #8

(Andrew) #9

Community Mesh Example

Off-grid Repeater Node Example

Video of repeater example


#10

Sorry. I’m a little sensitive lately. I’m just extremely tired of hearing people’s excuses for staying in the consumer paradigm instead of creating diy open source alternatives from civ’s waste.

I wish you the best of luck in finding gotenna devices hanging from the trees up there. :wink:


(Andrew) #11

I’ll be ferrying goTennas to treetops with the cheap drone I got for Christmas. They come in 4-colors so it will stay festive.

To others reading. I’m with Ernesto on this point: If y’all have access to salvaged stuff, make the best of it. I’m 6-8 hours (each way) and hundreds of $ in travel costs from the nearest landfill and Craigslist node. Using that much fuel and energy embodied in infrastructure to maybe find something I can use is rarely a “greener” alternative than ordering used eBay gear that travels to me on flights that are running whether they’re carrying a package for me or not.


#12

Make a wishlist and I’m sure that those of us that are stuck interacting with civ can send you stuff. I know I would. Money is seemingly always tight but I seem to attract junk. Just gave away a neat little drone that needed a minor repair last month.