Voice Over Internet Protocol, better known as VoIP, is not new. People have been enjoying voice communication over the Internet for years. What is new are the latest Amateur Radio applications of VoIP. Rather than relying on ionosphere propagation for long-distance communication, a growing number of hams are using the Internet in combination with VHF or UHF FM transceivers to span hundreds or thousands of miles.
There are several flavors of amateur VoIP in use today. Depending on how they are configured, these systems may involve repeater linking where two distant repeater systems share signals with one another. Another application is so-called simplex linking where one or more users with handheld or mobile ransceivers communicate directly with a base station (or node) that is linked to the Internet The one element that all amateur VoIP systems have in common is that the Internet acts as the relay between stations. The appeal of amateur VoIP is easy to understand. Technician licensees without access to HF can use these VoIP systems to enjoy a kind of Internet aided DXing, having conversations with other hams far beyond the range of their FM transceivers. General and Amateur Extra hams without HF stations at home can also benefit from VoIP in the same manner. Lets take a brief look at a few of the current incarnations of Amateur Radio VoIP.
EchoLink was developed by Jonathan Taylor, K1RFD, in early 2002. In an astonishingly short period of time, EchoLink has become one of the dominant Amateur Radio VoIP systems with more than 30,000 users worldwide. The free EchoLink software for Windows can be downloaded at www.echolink.org. When you start the EchoLink software, your computer taps the Internet to connect to an EchoLink server. Before you can make your first connection to the network, your call sign must be verified with the information in the FCC database. This can take minutes or hours, depending on the state of the system, but it helps reduce the chances of non-hams entering the EchoLink network.
Once youíre validated (you only do this once), the rest is easy. The EchoLink server acts like a telephone switchboard in cyberspace. It maintains a directory of everyone who is connected at any moment. After browsing the directory, you can request a connection between your computer and that of another amateur. Here is where it becomes interesting.
The ham on the EchoLink receiving end may be sitting in front of his computer with a headset and microphone. Or he may have his computer connected to a base radio at his station that is acting as an RF relay to a handheld transceiver or mobile rig. Or the destination station may be part of a repeater system. In any case, once the connection is established, anything you say will wind up being heard in the other amateurs headset, or transmitted over the air.
At your end of the EchoLink connection, you may be the one wearing the headset, or using a simplex connection to your base radio, or using a repeater. When you connect to an individual station, the custom is to call in the same fashion as you would during a traditional on-air conversation: W1ABC from WB8IMY. Or if you are connecting to a distant repeater system: WB8IMY, Wallingford, Connecticut. (You need to hesitate about 2 seconds before speaking to compensate for the delay.) The EchoLink servers also support conferencing where several amateurs can converse in roundtable fashion. There are even EchoLink nets that meet within these conference areas on a scheduled basis.
To run EchoLink youíll need a PC with Windows 98/2000/XP and a sound card. The software is easy to set up. A wizard function guides you through each step. If you want to enjoy EchoLink conversations while sitting at your computer, you will need a microphone headset. These are commonly available from several QST advertisers as well as RadioShack. The microphone plug attaches to the microphone input jack of your sound card and the headphone plug typically attaches to the SPEAKER OUT jack. In addition to setting up the EchoLink software, you may also need find it on the to adjust your sound card VOLUME and RECORDING control settings in Windows.
If you plan to connect a radio to your computer so that you can use EchoLink over an RF link, youíll need an interface. The strong enthusiasm for EchoLink is driven by the fact that it does not require a specialized hardware interface for connections to transceivers. All timing functions and DTMF decoding take place within the EchoLink software. This means that you can enjoy EchoLink with the radio of your choice by using common sound card interfaces such as those sold by West Mountain Radio (the RIGblaster folks), MFJ, TigerTronics and others. If you are already operating PSK31, RTTY, SSTV or similar modes with a sound card interface, you can become an EchoLink operator by simply downloading and installing the software no additional hardware or cable connections required.
There is also hardware interfaces specifically designed with VoIP in mind. Check out the ULI (Ultimate Linking interface) from James Milner, WB2REM, at www.ilinkboards.com. The ULI works with VoIP as well as the various Amateur Radio digital modes. It also offers built-in computer control of your radio. You can change frequencies, for example, by issuing commands on a remote UHF link, or via the Internet. It even allows remote rebooting of the station PC.
Also take a look at the multimode interface board designed by VA3TO. Youíll find it on the Web at www.ilinkca.com. iLink The iLink system is the brainchild of Graeme Barnes, MØCSH. iLink is one of the VoIP pioneers and is functionally quite similar to EchoLink, although it requires a specialized radio interface such as the ULI or VA3TO boards mentioned above. The iLink software is available for free downloading on the Web at www.aacnet.net/radio.html. EchoLink and iLink users are on separate server systems. With the rise of EchoLink, however, iLink has seen dramatically reduced activity in recent months. eQSO eQSO, created by Paul Davies, MØZPD, was designed to operate like a worldwide ham radio net. It is based around dedicated servers, and can be used from a personal computer or through a radio link (known on eQSO as an RF gateway). The eQSO software for Windows is available for free downloading on the Web at www.eqso.net, with online support available at www.eqso.net. A linking version of the software offers courtesy tones and a CW ID, and uses the computers COM port for keying the transmitter and reading the receivers squelch status. If a squelch line is not available, eQSO has an internal VOX function that can be selected. eQSO works with all the usual PCtoradio interface boards mentioned previously. Because there is no call sign validation, eQSO has security features that can be activated by administrators.
Administrators can mute or even block People who donít operate according to license privileges. Shortwave listeners (SWLs) are also encouraged to use eQSO, and they are trusted not to talk in rooms containing radio links. Those who do are muted or banned. However, SWLs can talk with hams in off-air rooms and many consider this as further encouragement to gain a license. Operators of RF gateways should avoid connecting their stations to these off-air rooms.