Winlink 2000 Utilizes enabling technologies and sound operating practices to provide a full-featured radio digital message transfer system, worldwide. Email transfer with attachments, position reporting, graphic and text-based weather bulletins and emergency communications are now available to the Amateur radio community by linking radio to the Internet.
The Winlink 2000 (WL2K) radio-email digital network system is intended to greatly extend the ability of the Amateur Radio to provide a public service to the greater community by linking to the Internet email system. The emphasis is to accomplish this while providing additional features that are of particular value to amateur users for use in emergency management and everyday use to those who may not otherwise have access to the Internet. It is a priority and commitment of the Winlink Development Team to provide these public services to the greater community through Amateur radio. Below is a discussion of the primary features of the system as it is implemented today. (If needed, a glossary of terms is available.)
Transparent Inter-working with Internet e-Mail
The primarily purpose of the Winlink 2000 network system is to assist the mobile or remotely located user, and to provide emergency email capabilities to community agencies. Because of this, WL2K supports a clean simple interface to the Internet ["SMTP"] e-mail system. Using its own B2F format, any message sent or received may include multiple recipients and multiple binary attachments. The radio user's email address, however, must be known to the system as a radio user or the message will be rejected. This simple Internet interface protocol has an added benefit in case of an emergency where local services are interrupted and the system must be used by non-Amateur groups as an alternative to normal SMTP email. Connecting to any one of the WL2K publicly used PMBOs via HF (radio), or the specialized non-public ARES PMBOs, can immediately and automatically connect a local amateur station to the Internet for emergency traffic. Using MS Outlook or MS Outlook Express, the Paclink mini-email server can replace a network of computers (behind a router) as a transparent substitute for normal SMTP mail. WL2K uses no external source for sending or receiving Internet email. It is a stand-alone function which interacts directly with the Internet rather than through any external Internet service provider.
Sophisticated Bulletin Distribution
To address the needs of mobile users for near real-time data, WL2K uses an "on-demand" bulletin distribution mechanism. (Note that such bulletins are not the same as traditional ["AX.25"] Packet Bulletins.) Users must first select requested bulletins from an available "catalog" list managed in Airmail. When bulletin requests are received by a ["PMBO"], a fresh locally cached copy of the requested bulletin is delivered. If no freshly local cached version is available, the PMBO accesses the Internet and finds the bulletin which is then downloaded to the ["PMBO"] and then sent to the user. The Global catalog currently includes over 700 available weather, propagation, and information bulletins, including, instructions for using the system, World news, and piracy reports. All WL2K PMBOs support a single Global catalog which insures users can access any bulletin from any ["PMBO"]. Bulletins can contain basic text, graphic fax or satellite images, binary or encoded files like GRIB or WMO weather reports. Local processing is used to re-process images to sizes suitable for HF Pactor transmission. The system prevents bulletin duplication and automatically purges obsolete time-sensitive weather bulletins and replaces them with the current version.
The system also has the ability to contain bulletins with attachment information which is local to each participating PMBO. This is especially useful for the non-public ARES PMBO which may house valuable procedural information pertinent to complex information or instruction needed by specific agencies in any community emergency.
Access to Radio Messages with a WEB Browser
There are times when radio users needs to receive (or send) messages when separated from their radio access. This frequently occurs on cruising yacht where they are unable to operate in port. By visiting an 'Internet café' or by any other access to a WEB browser, an amateur can read any of his pending messages or originate new ones. The WEB Browser Access is limited to text-based messages without the use of bulletins or file attachments. Of course, WEB Browser access to messages is password protected.
Access to Radio Message with Telnet
AirMail provides a super-fast replica of WL2K radio operations while directly connected through the Internet to one of the participating network station (PMBO) telnet servers. This method of obtaining messages over the Internet allows multiple attachments, catalog bulletins, and all other Winlink 2000 services normally available over radio channels, but at Internet speeds. In order to use this service, a user must currently be listed as a radio user, and obtain the password for each PMBO Telnet server used. Both TelPac, PacLink and AirMail support the ["Telnet"] client service to over 25 Winlink 2000 ["Telnet"] servers.
Reduction in Use of the HF Radio Spectrum
One of the most important objectives in the eyes of the Winlink development team was to reduce the use of the HF spectrum to only that required to exchange messages with a user, and to do that at full "machine" speeds. The HF spectrum is very crowded, and limiting the forwarding of messages between WL2K PMBOs to the Internet, a great deal of radio air time is eliminated, making the time and spectrum available to individual users either for message handling or for other operations. Efficient use of the Amateur Radio spectrum is paramount in the WL2K process. The Winlink development team is continually striving for more effective enabling technologies to accomplish more efficient communications through Winlink 2000. We welcome ideas, criticisms, complaints, compliments and suggestions that will improve the Winlink 2000 system.
Multiple Address Messaging
Messages handled by WL2K may have any number of addressees labeled either 'To:' or 'Cc:' and may mix any combination of radio and Internet ["SMTP"] style addresses. "Bcc" messages from the Internet are optionally accepted by the Winlink user, but are converted to normal "Cc" for legal reasons. The Winlink 2000 messaging system uses the ["SMTP"] email format for both messages to the Internet and messages to other radio users. However, in certain circumstances, only the call is needed for a Winlink 2000 radio user to email another radio user. Messages addressed to calls not known to the WL2K system are not accepted.
Transparent File Attachments
Multiple binary or text-based file attachments of any type or number may be attached to a message by simply selecting the file to be sent from a Windows selection dialog in the user's HF AirMail or the Winlink 2000 VHF/UHF Paclink server with Outlook or Outlook Express. Email message attachments sent through the Winlink 2000 system must be limited in size. User are provided an option to allow this limit to be determined (see below, "user selectable preferences.") When using the default B2F format, the protocol chosen by the user usually determines the file size of an attachment. A user may also turn off the ability to receive file attachments. Certain file attachment types are blocked from the system for the protection of the user from virus attacks.
Elimination of the Need for a "Home PMBO " with the use of "Intelligent Routing"
One of the primary design objectives of Winlink 2000 was to eliminate the need for any user to designate any specific "home" participating Winlink 2000 "PMBO" network station. Winlink 2000 (WL2K) uses a message routing system the makes note of which Winlink PMBO stations a user has connected over the past 90 days. Whenever a message is received for a user, it is forwarded to these specific PMBOs. When the message is read at any one of these PMBOs, a notice is automatically sent to the others indicating that the message was delivered, thereby, allowing it to be removed from the system. When a user stops using any specific PMBO for 90 days, messages will no longer be sent to that specific PMBO.
If a PMBO is used for the first time, the system makes note of it and forwards all pending messages to that PMBO. The next time the user connects to that PMBO, all of his pending messages will be there. This is of great benefit to mobile amateurs such as RVers, cruising vessels, and amateurs in remote locations that can only reach the network via HF (radio.) Users become known to the system simply by connecting to any WL2K PMBO.
Using a Client Program to Access the System
This is a great strength of the Winlink 2000 (WL2K) system. By using several optional easy-to-use, sophisticated programs at the user's station, a much more friendly and error-free interface is provided to the user and more features and services are supported than with the traditional teleprinter-style keyboard interface. This also reduces the connect time on an HF connection where the spectrum is so valuable, allowing more users to access a given PMBO than is possible in keyboard mode. Advanced formats may be implemented easier with the use of sophisticated client programs such as Airmail or Paclink with Outlook or Outlook Express client programs. Such user client interfaces allowing the same messages to be compressed for shorter transmission times. It also allows messages to be written off the air so that the shortest, most efficient time is spent on the radio transferring data at speeds impossible to obtain by composing messages in real-time while on the air. As with any other email usage, off-line composition of messages is the norm.
There is a terminal mode for interactive keyboard commands, allowing a terminal rather than computer-based software to connect to a PMBO. This method discouraged, but may be used for the listing and deletion of messages only. On HF radio, the client of choice is the Airmail program written and supported by Jim Corenman, KE6RK. This is a very elegant user program that supports all of the features of WL2K as well as many other digital modes and is provided for amateur use at no charge. For VHF/UHF "last mile" communications over AX.25 packet, both Airmail and the new Winlink 2000 Paclink server with single or multiple Outlook and Outlook Express clients may be used, depending on the required application.