Winlink, also known as the Winlink 2000 Network, is a worldwide radio messaging system that mixes internet technology and appropriate amateur radio radio frequency (RF) technologies. The system provides radio interconnection services including: email with attachments, position reporting, graphic and text weather bulletins, emergency/disaster relief communications, and message relay. The system is built and administered by volunteers without pecuniary interests. Winlink 2000 is a project of the Amateur Radio Safety Foundation, Inc. (ARSFI), a charitable entity and 501c(3) non-profit organization registered with the US Internal Revenue Service.
Winlink networking started by providing interconnection services for amateur radio. It is well known for its central role in amateur radio Emcomm messaging. The system runs several central message servers around the world for redundancy. During the past decade it increasingly became what is now the standard network system for amateur radio email worldwide. Additionally, in response to recent needs for better communications disaster response, the network has been expanded to provide separate parallel radio email networking systems for MARS, UK Cadet, Austrian Red Cross, and other communities.
Amateur radio HF email
Generally, email communications over amateur radio in the 21st century is now considered normal and commonplace. Email via High frequency (HF) can be used nearly everywhere on the planet, and is made possible by connecting an HF single sideband (SSB) transceiver system to a computer, modem interface, and appropriate software. The HF modem technologies include PACTOR, Winmor, and Automatic Link Establishment (ALE).
Amateur radio HF email guidelines
Amateur radio users in each country follow the appropriate regulatory guidelines for their license. Some countries may limit or regulate types of amateur messaging (such as email) by content, origination location, end destination, or license class of the operator. Origination of third party messages, i.e., sent to an end destination who is not an amateur operator, may also be regulated in some countries; those that limit such third party messages normally have exceptions for emergency communications. In accordance with long standing amateur radio tradition, international guidelines and FCC rules section 97.113, hams using the Winlink system are advised that it is not appropriate to use it for business communications.
The Winlink system is open to properly licensed amateur radio operators. The system primarily serves radio users without normal access to the internet, government and non-government public service organizations, medical and humanitarian non-profits, and emergency communications organizations. Duly authorized MARS operators may utilize the MARS part of the system. As of July 2008, there were approximately 12,000 radio users and approximately 100,000 internet correspondents. Monthly traffic volume averages over 100,000 messages.
Supported radio technologies
- 802.11 "WiFi"
- ALE (Automatic Link Establishment)
- APRS (Automatic Packet Reporting System)
- AX.25 Packet Radio
- TCP/IP (Telnet and other Wireless Technologies)
PACTOR, WINMOR, HSMM (WiFi), AX.25 packet, D-Star, TCP/IP, and ALE are non proprietary protocols used in various RF applications to access the Winlink network systems. WINMOR is a new open protocol. Three HF data protocols utilize proprietary-enabled, publicly documented modems: PACTOR-II, PACTOR-III, and PACTOR-IV. In amateur radio service, AirMail, an email software program used by the Winlink system, disables the proprietary compression technology for PACTOR-II and PACTOR-III modems and instead relies on the Open FBB protocol, also widely used by packet radio BBS forwarding systems in US.
Amateur radio interference issues
Like all modes of amateur radio, especially HF (High Frequency) ionospheric communications, where the spectrum is shared and the propagation is widely variable, users of the Winlink system have encountered potential for mutual interference. Normally, this interference is mitigated by various means, including: operator initiated connections, frequency agility, alternative regional nodes, and smart over-the-air modem protocols. The HF environment is a difficult communication problem, but modern modem systems have enabled fast and efficient data transfers, providing good alternatives to those who have few other viable options for electronic messaging in remote areas of the world.
US regulatory issues
In 2007, a US ham filed a formal petition with the Federal Communications Commission (FCC) aimed at abolition of Winlink, HF PACTOR, and other popular HF automatic data systems or modes; but, in May 2008 FCC ruled firmly against the petition. In the Official Order, FCC said, "Additionally, we believe that amending the amateur service rules to limit the ability of amateur stations to experiment with various communications technologies or otherwise impeding their ability to advance the radio art would be inconsistent with the definition and purpose of the amateur service. Moreover, we do not believe that changing the rules to prohibit a communications technology currently in use is in the public interest." 
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