HERMES and the Value of a Very Small Message

Key takeaways

• HERMES is an open-source project that sends data over shortwave radio.
• Under suitable conditions, shortwave signals can reach beyond the horizon without satellites or intermediate cell towers.
• Limited capacity makes short messages and essential information the priority.
• Running an independent network requires power, antennas, maintenance, and people who know the equipment.

When the internet goes down, “We’re safe” can matter more than a flawless video stream. For communities beyond the reach of telecom networks, finding a way to send that message is an everyday concern. Rhizomatica’s HERMES explores how shortwave radio and open-source software can provide a connection those communities operate themselves.

The atmosphere carries the signal

Shortwave communication uses the high-frequency, or HF, radio band: 3–30 MHz. Under suitable conditions, signals bend through the ionosphere and return to Earth, allowing communication beyond the horizon.

The ionosphere is a region of the atmosphere containing electrically charged particles produced by the Sun’s influence. Using it to carry signals can remove the need for a satellite relay or a chain of towers between two locations.

There is still hardware at both ends. Each site needs compatible radio equipment, an antenna, and power.

The atmosphere also gets a vote. Conditions in the ionosphere change with the time of day and solar activity. The same equipment in the same place will not always deliver the same connection quality.

That variability is part of the operating environment. Anyone planning around the link has to account for it.

A connection you control has a specific job

A radio link between a remote village and a regional hub creates a route for exchanging data. Access to the wider internet requires an additional connection somewhere along the way.

That distinction shapes what HERMES can offer. A working link does not automatically put every website and online service within reach. Its immediate value is giving people a way to communicate where a telecom operator’s network does not reach.

Open source adds another kind of control. People can inspect the software and, with the necessary skills, adapt it to local languages or working practices.

But a public codebase does not come with a maintenance team. Someone still needs to understand, modify, and support it. Operational capability matters as much as equipment ownership.

Small messages make the capacity go further

Shortwave data links have limited bandwidth. Noise and weak signals can also force retransmissions, adding to the time needed to deliver a message.

The useful measure is time to deliver essential information. Even a small message may take a while when conditions are poor.

Consider a hypothetical 1 KB text message and a 1 MB photo. The photo contains roughly 1,000 times as much data. Those figures illustrate payload size; they are not measurements of HERMES performance.

That difference changes how a service should work:

• Give safety updates, locations, and urgent requests priority.
• Send inventory counts and supply needs as concise text.
• Organize work so it can continue while a reply is delayed.

A request for medicine might need only an item name and quantity. A photograph of the entire shelf asks the connection to carry much more information. Agreeing on a simple message format beforehand can reduce the payload further.

These choices make limited capacity more useful. They do not increase the underlying radio speed.

Independence includes the repair work

Installation is the beginning of running a network. A power failure or damaged antenna can interrupt the connection, and replacement parts may take time to reach a remote site.

Someone needs to check the equipment, diagnose faults, and make repairs. Operating procedures need to be shared so the whole system does not depend on one person being available.

Before asking how far a link can reach, it helps to settle three practical questions: who needs to communicate, what information must get through, and how much delay is acceptable.

An additional communication route can also be useful where conventional networks already exist. For emergency use, it needs regular practice: actual messages sent and received, with power, antennas, and equipment checked along the way.

HERMES makes sense where people value a communication channel they can operate themselves and can accept its constraints. The starting point is the message that matters most. If the usual network disappeared tomorrow, what would you need to say first?