Astronomy, IoT and the Mesh

I've been into astronomy and radiocomms for as long as I can remember. More recently, I have latched onto the LoRa scene, exploring both MeshCore and MeshTastic options for off-grid communications and, well, just for fun. I was wondering about an astronomical application and, well, I made something along those lines.

But first, what is this all about?

So here's the gist on LoRa. It stands for "Long Range," and it's a radio technique that trades speed for distance and battery life. Instead of blasting out a strong, fast signal like WiFi or Bluetooth, LoRa spreads a tiny amount of data across a wide range of frequencies really slowly, which lets a receiver pick it out of the noise from miles away using barely any power. You're not streaming video or even much text with it, just small chunks of data, but you can send them from a hilltop to a valley ten miles off using a radio that runs off a coin cell for weeks.

Diagram shows that while Bluetooth and Wi-Fi are fairly tightly bound to a small area from any given device, LoRa is way more expansive.

That's the raw ingredient. Meshtastic and Meshcore are two different recipes built on top of it. Meshtastic is the older, more established project, it turns a bunch of cheap LoRa devices into a mesh network, where every node relays messages for its neighbors, so your text message can hop node to node until it reaches someone miles beyond your own radio's range. No cell towers, no internet, no monthly bill, just a growing web of hobbyist radios passing messages along, kind of like how those FT8 signals I mentioned bounce off the ionosphere to get where they're going, except here your neighbor's radio is doing the bouncing. Meshcore is the newer kid on the block, aiming at the same basic idea (off-grid, decentralized messaging over LoRa) but with a different routing philosophy, it's built to be more efficient about how it floods messages through the network, and it's got encryption baked in a bit more deliberately from the start. Both are still very much active, evolving projects, so which one wins out, or whether they just end up serving different niches, is still an open question worth watching.

Meshtastic floods every message through all nearby relays; Meshcore routes it along one known path.

So, I have put together several nodes and repeaters for both Meshcore and Meshtastic. The former seems to be "cooler" - easier interface, more lively, friendly crowd using it, and it just kinda makes more sense overall. Meshtastic is out there, but I don't see a lot of activity in my area on it. On Meshcore, I am able to communicate with people quite far away, in once case around 110 miles away using this LorRa model. So, as of now, I am using Meshcore for external communications and mesh building, and using Meshtastic for my own private Mesh, which includes the little project I just completed and shall now explain.

My Meshtastic node, which I can access via the Meshtastic app on my phone. This is Heltec v4 board.

A view of Mestastic repeater node which sits on my chimney.

Keeping an eye on climate within my observatory has always been of interest. Sometimes I run things by remote, so having an eye on things like dew is important. Yes, you can buy stuff for this, but I wanted to make something from scratch utilizing the LoRa/Mesh technology. So, I acquired a Heltec v4 board and an M280 climate sensor. I wired them together, added a battery, high gain antenna and a charging system that connects to my observatory's solar charger. 

Solar power control unit on the left, the Meshtastic climate sensor I constructed on the right.

It took a while to perfect, but now I have a "node" within my observatory that send me temp, humidity, pressure and dew point telemetry every thirty minutes. Data is sent from that node to my rooftop Meshtastic repeater, then to my personal node which I can connect to via the Meshtastic app on my phone. The telemtry node uses a 3.7v 1100mah battery, which is kept charged by the observatory's solar charger. So, I can be anywhere and see what climate conditions are like inside the observatory at any given time - very useful!

A view of the node's telemetry data from the Meshtastic app.

A different view of historical telemtery data from the observatory node.

Anyway, it was a fun project that combined radiocomms and astronomy. This will give me useful information for remote observatory operation, and is especially useful given it's my own infrastructure, not dependent upon an internet or mobile phone service provider. 

How it all comes together.

A view of the telemetry node inside the observatory.