Part of our Getting On The Air: Modes, Operations, and Making Contacts guide.
FT8 is amazing at making contacts in terrible conditions, but it has a limitation: the exchanges are rigid and automated, so you cannot really have a conversation. JS8Call was created to fix exactly that. It takes the weak-signal magic that makes FT8 work and turns it into something you can actually chat and send messages with. Here is what it is and why preparedness-minded operators love it.
What JS8Call is
JS8Call is free software that combines the FT8 signal technology (it is built on the same underlying approach) with a keyboard-to-keyboard messaging system. Instead of the fixed, automated exchanges of FT8, JS8Call lets you type free-form text messages that get through under very weak-signal conditions with low power. The name comes from the JS8 mode it uses, plus the idea of “calling” other stations.
The tradeoff for that flexibility is speed. JS8Call is slow compared to voice or even normal digital keyboard modes, because it prioritizes getting the message through over getting it through quickly. You are trading speed for the ability to communicate when almost nothing else will.
What makes it special
- Real conversations. Unlike FT8, you can send actual text, not just a canned exchange. That means genuine keyboard-to-keyboard chatting.
- Store and forward messaging. You can leave messages for other stations that get relayed and picked up later, a bit like a very slow, radio-based messaging system.
- Relaying. Messages can be passed through intermediate stations to reach someone beyond your direct range.
- Group and directed calls. You can address specific stations or groups, and stations can automatically respond to certain queries like a signal report or their location.
- Weak-signal performance. Because it inherits FT8’s technology, it works with low power and modest antennas in poor conditions.
Why preppers and emcomm folks like it
JS8Call has a strong following among emergency communications and preparedness-minded hams. The reason is simple: it lets you pass real information (not just signal reports) over long distances with very little power and a simple wire antenna, even when conditions are poor. If the grid is down and you need to get a message to someone hundreds of miles away, a mode that works on a few watts and can relay through other stations is enormously valuable.
It runs off battery power easily because of that low power draw, and it does not depend on any internet or infrastructure. It is radio to radio, station to station.
How it compares to FT8
Think of it this way. FT8 (through WSJT-X) is optimized for making as many quick contacts as possible in rough conditions. JS8Call is optimized for actually communicating information in those same rough conditions. Different goals, same underlying weak-signal strength.
If you already run FT8, your station is basically ready for JS8Call too, since it uses the same kind of radio-to-computer audio and CAT control connection. It is free to download, and it is well worth adding to your toolkit, especially if resilient communication is part of why you got into the hobby.