Amateur radio communication with digital modes: FT8, JS8Call, PSK31

Amateur radio has a rich history spanning over a century, and despite the rise of the internet and mobile communications, it remains a vibrant and evolving hobby. The advent of digital modes has transformed how radio amateurs communicate — enabling long-distance QSOs with minimal power and bandwidth.

In this article, we explore the three most popular digital modes in amateur radio: FT8, JS8Call, and PSK31. We’ll explain how each works, what equipment and software you need, and how to get started — whether you’re a licensed operator or just discovering the world of digital radio.

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1. What are digital modes in amateur radio?

Digital modes use a computer (or decoder) to convert typed or pre-defined messages into audio tones that are transmitted via SSB (usually USB). On the receiving end, software converts these tones back into text.

Key benefits:

• Works with extremely weak signals (as low as -24 dB)

• Efficient: uses very little bandwidth

• Enables automated QSOs

• Suitable for QRP operation

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2. A short history

• 1990s – PSK31 introduced as a real-time digital chat protocol

• 2010s – Joe Taylor (K1JT) releases WSJT-X for weak-signal modes

• 2017 – FT8 emerges, becoming the most popular digital mode

• 2018 – JS8Call launches, combining FT8’s robustness with messaging flexibility

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3. FT8 – Worldwide QSO in 15 seconds

3.1 How it works

• FT8 = Franke-Taylor 8-FSK modulation

• Operates in synchronized 15-second intervals

• Sends short, structured messages (call sign, grid, signal report)

• Requires accurate system time via NTP synchronization

3.2 Advantages

• Works at very low signal levels (-20 to -24 dB)

• Automated QSOs — fast and efficient

• High activity in nearly every HF band

3.3 Required software

• WSJT-X – Official software for FT8

• JTDX – Alternate client with enhanced decoding

• GridTracker – Visualization and real-time logging

3.4 Suggested FT8 frequencies (USB mode)

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4. JS8Call – FT8 with flexible messaging

4.1 What is JS8Call?

JS8Call is based on FT8’s modulation scheme but allows for free-text messages, making it more suitable for personal chats, emergency communications, and mesh-style networking.

4.2 Key features

• Asynchronous communication — send messages anytime

• Store-and-forward messaging

• Relays, auto-responses, heartbeat beacons

4.3 Required software

• JS8Call – Official client

• NTP time sync required for proper operation

• Optional tools: GridTracker, logging software

4.4 Recommended frequencies

• Typically +1 or +2 kHz from FT8 frequencies

• Example: 40m = 7.078 MHz (USB)

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5. PSK31 – The classic digital chat mode

5.1 How it works

• Phase Shift Keying, 31.25 baud rate

• Real-time, typed QSO with visible characters

• Very narrow bandwidth (~31 Hz)

5.2 Advantages

• Easy to learn, human-readable

• Real-time text chat feel

• Operates well with modest hardware

5.3 Required software

• Fldigi – Popular for PSK31, RTTY, Olivia, and more

• Ham Radio Deluxe (DM780) – Powerful GUI option

• QSSTV, quisk – Linux alternatives

5.4 Common PSK31 frequencies

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6. Required hardware and setup

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7. Getting started: step-by-step

Step 1 – Get licensed

In most countries, including Hungary, transmitting in amateur bands requires an official amateur radio license issued by the telecommunications authority (e.g. NMHH).

Step 2 – Choose your mode and software

• FT8 → WSJT-X

• JS8Call → JS8Call

• PSK31 → Fldigi

Step 3 – Configure your audio interface

• Set correct input/output audio devices

• Use VOX or PTT for keying

Step 4 – Synchronize system time

• FT8 and JS8Call rely on accurate timing — install and configure NTP

Step 5 – Connect transceiver to PC

• CAT control (for tuning/logging)

• USB or serial PTT interface

Step 6 – Start operating!

• Watch the waterfall display

• Respond to CQ calls or send your own

• Log QSOs in ADIF format

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8. Legal considerations (Hungary)

• Amateur radio transmission requires a license from NMHH.

• You will receive a callsign after passing the exam.

• Digital modes (FT8, PSK31, JS8Call) are fully legal in their respective amateur bands.

• Follow national band plans for frequency usage.

? Additionally, it’s worth noting that FT8 and JS8Call are increasingly being used on the license-free CB (Citizen Band) radio frequencies, especially around 27.245 MHz. While these modes were originally designed for amateur radio bands, they have found a growing niche among hobbyists using QRP power levels within CB band limits. In many countries, including Hungary, using digital modes on CB is not explicitly prohibited, as long as users stay within the legal constraints (e.g., max 4W AM/FM/SSB output, no harmful interference).

⚠️ Note: Digital mode operation on CB bands remains in a grey area in some jurisdictions. Use responsibly and avoid interference with other users.

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9. Pros and cons of digital modes

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10. Future trends

• AI-assisted decoding for noisy band conditions

• Hybrid digital voice/data protocols (e.g. FreeDV)

• Geostationary satellite modes via QO-100

• Mobile FT8/JS8 apps with SDR dongles

• Decentralized messaging networks with JS8Call

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Conclusion

Digital modes like FT8, JS8Call, and PSK31 are transforming the amateur radio experience. Whether you’re a DX hunter, a minimalist QRP operator, or a digital experimentation enthusiast, these modes offer exciting opportunities — even in low-power, portable, or urban setups.

Thanks to their efficiency, reliability, and global adoption, digital modes are here to stay. And if you’re not yet licensed, there’s a growing community exploring these tools even in license-free bands like CB, responsibly and creatively.