C4FM / System Fusion

C4FM, commonly used with Yaesu System Fusion equipment, provides digital voice, limited data capabilities and internet-linked communication through the WIRES-X network.

Key Features

• Clear digital voice communication
• Automatic Mode Select on compatible radios
• GPS location and station information
• WIRES-X rooms and internet linking
• Digital group monitoring functions

DMR

DMR is a widely used digital voice standard that uses time-division technology to support two communication time slots on one repeater frequency pair.

Key Features

• Regional and worldwide talkgroups
• Two time slots on compatible repeaters
• Large worldwide repeater network
• Efficient use of radio spectrum
• Supported by many radio manufacturers

Common Networks

• BrandMeister
• TGIF Network
• DMR-MARC and regional systems

D-STAR

D-STAR is an amateur-radio-focused digital voice and data system. It is especially known for callsign routing, reflector connections and digital data capabilities.

Key Features

• Callsign-based routing
• Reflector and gateway connections
• Short text and GPS information
• Digital voice and data operation
• Strong support in many Icom radios

P25

P25 was developed primarily for public-safety radio systems, but it is also used by some amateur radio operators, clubs and digital voice enthusiasts.

Key Features

• Digital voice communications
• Commercial and public-safety radio compatibility
• Conventional and networked operation
• Used by specialized amateur repeaters

NXDN

NXDN is a narrowband digital radio protocol developed for commercial and professional communications. It is occasionally used on amateur radio repeaters and experimental systems.

Key Features

• Narrow channel bandwidth
• Efficient use of available spectrum
• Good digital voice quality
• Support in selected Icom and Kenwood equipment

M17

M17 is a modern open-source digital voice and data protocol developed by and for the amateur radio community. Its design emphasizes openness, experimentation and nonproprietary technology.

Key Features

• Open protocol and open-source development
• Digital voice and data capability
• Internet-linked reflector operation
• Designed specifically for amateur radio
• Growing radio and hotspot support

FT8

FT8 is one of the most widely used HF digital modes. It allows stations to complete structured contacts using signals that may be too weak to hear clearly by ear.

Key Features

• Excellent weak-signal performance
• Structured, computer-assisted contacts
• Fifteen-second transmission periods
• Popular for worldwide DX communication
• Available through WSJT-X and compatible software

FT4

FT4 is similar to FT8 but uses shorter transmission periods. It was designed to support faster contact rates, especially during contests.

Key Features

• Faster contacts than FT8
• Structured message exchanges
• Useful for digital contests
• Good weak-signal capability

JT65

JT65 was designed for extremely weak-signal communications. It has been widely used for specialized work including Earth-Moon-Earth contacts, although FT8 has replaced it for many everyday HF applications.

Key Features

• Very high weak-signal sensitivity
• Long transmission periods
• Structured contact exchanges
• Historically important in weak-signal operation

JS8Call

JS8Call uses weak-signal technology related to FT8 but supports conversational keyboard messaging rather than only structured contact exchanges.

Key Features

• Keyboard-to-keyboard conversations
• Weak-signal text communication
• Directed calling and group messaging
• Message relaying and store-and-forward functions
• Useful for off-grid communications

PSK31

PSK31 is a narrow-bandwidth digital mode designed for real-time keyboard-to-keyboard conversations. It remains a popular introduction to traditional HF digital operation.

Key Features

• Real-time typed conversations
• Very narrow signal bandwidth
• Effective at relatively low power
• Supported by many digital-mode programs

RTTY

RTTY is one of amateur radio's oldest digital communication modes. Modern operators usually generate and decode its signals using computer software rather than mechanical teleprinters.

Key Features

• Long history in amateur radio
• Real-time text communication
• Popular in digital contests
• Widely supported by logging and decoding software

Olivia

Olivia is designed to maintain readable text communication through noise, interference, fading and weak-signal conditions.

Key Features

• Strong resistance to noise and fading
• Keyboard-to-keyboard conversation
• Multiple bandwidth and tone configurations
• Good performance under difficult conditions

Winlink

Winlink is a worldwide radio email system that allows licensed operators to send and receive messages over HF, VHF or UHF radio links. It is widely used in emergency communications and remote operations.

Key Features

• Email through radio gateways
• Peer-to-peer radio messaging
• Forms and limited attachments
• HF, VHF and UHF connectivity options
• Widely used by emergency communication groups

APRS

APRS is a real-time tactical information system commonly used for vehicle and operator tracking, short messages, weather information and event coordination.

Key Features

• GPS position reporting
• Vehicle and portable station tracking
• Short text messaging
• Weather station reporting
• Digipeater and internet gateway support

Packet Radio

Packet radio sends computer data over amateur radio using packet-based networking. It helped establish early amateur radio bulletin boards, messaging systems and digital networks.

Key Features

• Connected and unconnected data communication
• Bulletin board and mailbox systems
• Digipeater networking
• Foundation for APRS communications

VARA

VARA is a family of software modems commonly used with Winlink. Different versions support HF, narrow FM and wideband FM radio connections.

Key Features

• High data throughput for radio links
• Strong forward error correction
• VARA HF, VARA FM and other versions
• Well suited for messages and file transfers

SSTV

SSTV sends still images as audio tones over a radio channel. Operators can exchange photographs, graphics, station information and visual QSL images.

Key Features

• Color still-image transmission
• Commonly used on HF frequencies
• Multiple image modes and resolutions
• Used during amateur radio special events

Digital Image Transmission

Digital image applications transmit image files using error-corrected data signals. They can provide cleaner received images than traditional SSTV when the complete file is successfully decoded.

Key Features

• Error-corrected image transfer
• Higher image quality than many SSTV modes
• Computer-based transmission and reception
• Performance depends on signal conditions

AREDN

AREDN uses compatible network equipment and amateur radio spectrum to build high-speed, self-configuring IP data networks for emergency and public-service applications.

Key Features

• High-speed IP data networking
• Voice-over-IP and video applications
• File sharing and local web services
• Self-configuring mesh links
• Useful for emergency communication infrastructure

MeshCore

MeshCore is a low-power mesh communication platform designed for decentralized text messaging and portable off-grid networking through compatible radio devices.

Key Features

• Off-grid text messaging
• Peer-to-peer and relayed communication
• Portable, low-power equipment
• Expandable mesh coverage
• No cellular network required