DIGITAL MODES

FT8 (Franke-Taylor design, 8-FSK modulation) revolutionized amateur radio DXing. Operating at -20dB SNR, it enables worldwide contacts with minimal power. The 15-second transmit cycles and automated decode make it ideal for stations with compromised antennas or challenging propagation.

FT4 is optimized for contesting with 7.5-second transmit periods — twice as fast as FT8. Slightly less sensitive but enables rapid-fire QSOs during contests and band openings. Same WSJT-X software, different mode selection.

Weak Signal Propagation Reporter is a beacon mode for studying propagation paths. Transmit your callsign and grid at extremely low power and watch where you're heard worldwide. Perfect for antenna testing and understanding band conditions.

Originally designed for Earth-Moon-Earth (EME) communications, JT65 uses 65-tone MFSK with powerful error correction. Slower than FT8 but with superior weak signal capability. Still popular for moonbounce and challenging paths.

JS8Call builds on FT8's weak signal foundation but enables real keyboard-to-keyboard conversations. Store-and-forward messaging, group calls, and heartbeat beacons make it ideal for emergency communications and off-grid messaging.

Q65 is designed for troposcatter, ionospheric scatter, and EME on VHF and higher bands. Handles rapid fading and Doppler spread better than JT65. Multiple sub-modes (A through E) offer different cycle lengths for various propagation conditions.

WinLink is a global radio email system used extensively for emergency communications. Send and receive email via HF, VHF, or UHF when internet is unavailable. ARES/RACES and emergency management rely on WinLink for disaster response coordination.

VARA (developed by EA5HVK) is the preferred modem for WinLink, offering speeds up to 8490 bps on HF and 25,000 bps on FM. Free version available with reduced speed; licensed version unlocks full capability.

AX.25 packet radio is the foundation of amateur digital communications. Still used for BBS systems, keyboard-to-keyboard chat, and as the backbone for APRS. 300 baud on HF, 1200/9600 baud on VHF/UHF.

NBEMS uses Fldigi's suite of modes (MT63, Olivia, MFSK) combined with Flmsg for form-based messaging and Flamp for file transfer. Popular for EmComm exercises and real deployments. No special hardware needed — sound card only.

APRS provides real-time tactical information — position, weather, messages, telemetry. Perfect for tracking mobile stations, event communications, and emergency response. Digipeaters and I-gates create a worldwide network viewable on aprs.fi.

Beyond position reporting, APRS supports two-way text messaging between stations. Send messages to specific callsigns, query weather stations, and communicate during events or emergencies. Messages can bridge RF and internet.

CW remains the most efficient mode for weak signal work. Minimal bandwidth, excellent noise immunity, and works when voice can't. No computer required — just your brain, a key, and a radio. K4JMC members actively support CW learners.

RTTY (RadioTeleTYpe) uses FSK with 45.45 baud Baudot code. Dating to the 1930s, it's still popular for contesting. Simple, robust, and supported by all major logging software.

PSK31 revolutionized keyboard-to-keyboard communication in 1998. Its narrow 31 Hz bandwidth allows dozens of QSOs in a single SSB channel. Perfect for ragchewing with low power.

Olivia uses multiple tones with forward error correction for excellent performance in noisy and multipath conditions. Popular for EmComm and reliable text transfer when other modes struggle.

SSTV transmits still images over narrow bandwidth audio channels. Multiple formats (Martin, Scottie, Robot) offer different resolution/speed tradeoffs. The ISS regularly transmits SSTV images during special events!