JS8Call an overview for new users


JS8Call has been in around for a few years now, but its sadly still not very popular. Many Amateur Radio Operators around the world are using the WSJT-X software constantly to make contacts comprising of a simple signal report exchange and that’s fine, but its not for everybody. If you have tried FT8 you will already know of its great weak signal capabilities allowing DX Contacts when conditions are difficult. So what if you could use a mode that has similar properties to FT8 but also allow a keyboard to keyboard communications as well as integration to allow messages and location reports to be sent into the APRS network? Well, in a nutshell that’s what JS8Call does.

Back in March of 2018 I managed to get involved in the testing of some new software for Amateur Radio. I joined a very small team of Operators who were mainly in the USA but also three in Europe, including myself. This software was called FT8Call, the original name of what is now called JS8Call.

As you may have already deduced from the original name of the software it’s a new digital mode that is built upon the popular weak signal digital mode FT8. If uses the same modulation as FT8 allowing it to be decoded at -24Db, and it also uses the same 15 second timer to send out its messages.

It is there that the similarities end though, because unlike FT8’s simple Signal Report exchange format, JS8Call allows free text keyboard-to-keyboard communications.

Recent updates to JS8Call added 3 new speed modes for JS8Call and integration to APRS that means if you send an APRS message using JS8Call a receiving station with an internet connection will forward that to the APRS network. More about that later.

Hardware Requirements

You don’t need the latest high-powered computer to run it. It will run as Happily on the Raspberry Pi as it does on the latest high-end laptop. Supported operating systems include various distros of Linux, Windows 10 and MacOS X (the standard MacOS installer will also run on the new apple silicone). That said there are also many operators in the pre-release test that are running it on older operating systems such as Windows XP and Windows 7.

Like any other computer based digital mode you also need some way of connecting the computer to the radio via a sound card interface of some kind. On my PC and Icom IC-7300 this is done with one USB Cable for CAT Control and the Sound Interface provided in the Radio. With the introduction of radios with Wifi such as the Icom IC705 (my favourite radio) you can connect the computer completely wirelessly to the radio which removes the need for another wire which is great news especially in the field.


Installation on the supported operating systems is a simple case of downloading and running the installer package. You can find the latest installation packages on the JS8Call website by following the download link at the top of the page https://js8call.com

User Interface

The user interface is laid out well and does also work quite well on a touch screen interface as well as with a mouse. The main window is split into the Band Activity pane (showing messages you have decoded).

Incoming Message Activity Pane, Call Activity pane (showing the list of callsigns you have heard), the Message box (here you will enter your outgoing messages) and the Waterfall at the bottom giving you a visual indication of where the signals are in the passband – you can also select the frequency offset you want to use here. The six buttons top right display settings in use and you can click them to enable/disable or bring up a menu of options (also available in the Menus top left)

Using JS8Call

So lets get down to actually using the software. If you have already installed and used WSJT-X then JS8Call should work right away, if no you will need to make sure your connection from computer to your radio is correctly set up. There are some guides on my website to get you started (link at end of this article). Once installed there are a couple of things you need to set up. First enter your callsign on the General/Station settings page. Then entry your Maidenhead Grid locator and customise your Station messages, and finally set up your radio interface and select the sound card to use.

Back in the Main User interface calling CQ is as simple as clicking on the CQ button, JS8Call will put your CQ message in the message window and send it at the start of the next 15 second time frame. Once you receive a reply you can click on the station’s callsign in the Call activity pane and then type your message into the message box and click send, JS8Call will automatically add your callsign and the selected station’s callsign to the message and send it.

You have the option to use 4 different tx speeds (you can receive and decode all no matter which is selected) the speeds and their properties are (details taken from the JS8Call Documentation)

  • Slow – 30 second frames – 25Hz bandwidth – and around 8WPM decoded down to -28dB
  • Normal – 15 second frames – 50Hz bandwidth – and around 16WPM decoded down to -24dB
  • Fast – 10 second frames – 80Hz bandwidth – and around 24WPM decoded down to -20dB
  • Turbo– 6 second frames – 160Hz bandwidth – and around 40WPM decoded down to -18dB

Hint: I tend to call CQ using Normal mode and then switch to a faster speed once I see what the reported SNR is between myself and the far station. If trying for DX select slow mode to call CQ and then switch once contact is established (if possible) I have had some quite lengthy QSOs using slow mode. Great results but you need to be patient 😉

That’s all there is to it. There is some automation like the ability to set it up for your station to reply to directed commands/messages automatically but the actual QSOs are comtrolled by the operator with free text or the use of Saved messages which can be pre-defined by the user. There is also a “Heartbeat” function that will send out your callsign and grid locator at user-defined intervals. This is not a CQ call but a mechanism that lets others know your station is on the air and they can call you direct, or maybe send your station a relay command to pass a message to someone that they cannot hear.


You can use JS8Call to send messages and locations into the APRS network and view on APRS.fi. By formatting your outgoing message correctly you can send emails, APRS messages, SMS messages (if supported in your country), position reports and even spot yourself for SOTA. Ive written a python app with user interface that you can use to do this, but all it does if format the text correctly. It uses the JS8Call API to send the text.

The Power of Low Power

The great thing about this mode is that it can be decoded at -28dB. Which means that you don’t need to run your radio at full power to chat with a DX station. During the recent QSO party weekend I was able to set my IC-7300 at minimum power (0% which gave an output power of approx. 350mW) and have a conversation with Julian OH8STN in Finland over 1300miles away. I was also getting acknowledgments to my “Heartbeat” from stations in North America during the evening.

What’s the Cost?

JS8Call costs nothing, it’s based on open source software and although parts of JS8Call contain code that Jordan KN4CRD owns the copyright to he has assured us that he will never charge for the software.


JS8Call has come on in leaps and bounds since I joined the test team back in may. And its evolved into what’s going to be a great mode for communication over long distances using relatively low power. Jordan has done some fantastic work and is very supportive of new users on the groups.io groups and is happy to accept requests for improvements and new functionality. He’s doing Amateur Radio a great service and I can’t thank him enough for that.

If you haven’t yet tried JS8Call then consider giving it a go, there are a lot of users out there who are happy to help you get up and running, and there are a few facebook groups you can join and of course the JS8Call website contains links to all the documentation. You can always give me a shout and I will be happy to help!



My website and software:


JS8Call website


Download JS8Call and Documentation