Ham Radio and VolP
sit still amateur radio without the radio? Maybe, destroyed in an area due to a disaster, it is unlike- maybe not. On one hand, the communication ly to disappear worldwide, and so radio will still Iis the key, regardless of medium. On the other serve best as the "last mile" (or last hundred miles) hand, radio is at least half the equation, and the for critical communications. (If the lnternet did name. If we were to lose access to the "radio" part, somehow go down worldwide, there would be how many of us would still be involved? larger issues afoot than amateur radio, of course, With that in mind, this month we will delve into although amateurs would most likely still be able the world of Voice over lnternet Protocol, or VolP, to communicate.) as used today in amateur radio. Some folks pro- claim lnternet linking as a death knell for amateur What Is It? radio. I disagree. The same predictions of doom What exactly is VolP and how does it work? I can came about when people started linking packet only offer avery basic overview, as the topic would nodes over wirelines (the Internet was not yet real- easily fill a textbook. ly a factor), but today we have a stronger VHF Voice over lnternet Protocol is exactly that: packet system, providing "last mile" data connec- Voice signals, as we often use for radio commu- tions instead of trying to cover immense distances. nications, being sent using the lnternet protocol. In other words, we're making the best use of the Much like digital voice, we start by capturing a technology. voice (or other sound) signal and "digitizing" it, So it will go with VolP and other synergies be- turning the analog audio stream into a digital bit tween radio and wires. It doesn't make much stream. How exactly we capture it, how many bits sense to use (relatively) unreliable radio links for are needed to represent a particular sound, and a job the lnternet can do a zillion times better. It just how faithful the reproduced sound will be to will not cause us to lose spectrum, or reduce the the original all are technical details. Hardware, popularity of radio; instead, more will use it be- software, and configuration settings control these cause it works so well. Do you think a major radio finer points, but we do not have to even under- manufacturer (Yaesu) would develop a VolP sys- stand it in order to use it. tem (WIRES-II) if it thought it would make radio Virtually any computer with a sound card is able obsolete? Even if the lnternet infrastructure is to record a voice signal and save it as a file. One / could then e-mail that file to a friend, but that isn't *P.O. Box 114, Park Ridge, NJ 07656 really VolP, since it is not being done in real time. e-mail:
A screen shot of an EchoLink QSO in progress, showing the Kl RFD repeater linked to the KlUHF repeater. (Courtesy of K1 RFD)
2 December 2004 Visit Our Web Slte signal, but how you transport the data Are WinLink 2000 and PacTOR the Enemy? to another computer and then recon struct it back into sound, in real time. Just a short note about the controversy over the supposed "requirement" that WinLink Early VoIP was used as a replacement 2000 (recently recommended by the ARRL for ARES work) will only operate with PacTOR. for telephone calls. Any two people who Let me state it plainly: There is no such requirement. WinLink 2000 will work with any could connect to the Internet could carry data mode that is error-free. This includes Packet, PacTOR, and many other modes, but not "non-error-free" modes such as PSK31. The introduction of any error into an e-mail on a half-duplex (limited by the sound header obviously is a bad thing. card) telephone conversation for as long With that in mind, there is nothing out there that beats PacTOR III in performance or as they like, with no cost above their spectrum efficiency, with PacTOR II not far behind. Many are rankled by the "closed access to the Internet. Voice quality was source" nature of PacTOR, but you can't blame the inventors for wanting to protect their often less than toll-quality, a technical intellectual property. Others get upset when the PacTOR "robots" come up on frequency compromise to limit data bandwidth in the and blow away all the PSK31 QSOs, something I experience regularly. While it is rude days of 28.8k dial-up, while dropouts and and maybe violates Part 97, we all need to work together to find a home for these oper disconnections were not uncommon. ations instead of banning them altogether. The transport mechanism is a little WinLink 2000 and PacTOR are valuable tools we have, so let's address the specific more complex. The Internet works issues they bring up cooperatively instead of blindly condemning the good with the bad. much like a packet-radio network, in that data is sent as little packets of data, rather than a continuous bit stream (like PSK31 or RTTY). In order for VoIP to terns for amateur radio are IRLP distant stations with HF EchoLink gate work, you need to get all the packets to (Internet Radio Linking Project, by Dave ways would still be there, as would the the other end of the connection, in the Cameron, VE7LTD) and the newer Internet. Once you get into the EchoLink right order, and do it fast, as nobody EchoLink (by Jonathan Taylor, K1RFD). system, you can go whereveryou need. wants a 5- or 10-second delay in a com I'll focus on EchoLink, since I am more For example, in December 2002 a pow munications channel. Because it is familiar with it, but that shouldn't make erful typhoon struck Guam. Links to the voice, a few missed packets or you think any less of IRLP or any of the island via HF were unsuccessful, but a moments of silence are okay, as is a other VoIP systems out there (such as voice channel was successfully estab delay of about a second. eQSOandWIRES-ll). lished via EchoLink. Moving from telephone calls to As an over-the-air EchoLink user, you don't need any special equipment, just repeater linking wasn't a huge leap, but Setting It Up that's not to say it was easy to do. Much your regular radio. When it is linked in, it of the basic work—audio digitizing and seems as if your local station just has Of course, as a Local Radio User (may decoding, the Internet and transport wider coverage, although the "rest" of the be just driving around in your car), you mechanisms, computer sound cards— coverage could be half a world away. can set up a link between your local sta was already there, but putting it all You send DTMF tones (Table I) to con tion and some distant one, and all you together, in a way that prevents non- trol the link. If you know the EchoLink need is a radio. If you run the EchoLink amateurs from accessing a transmitter, Node Number (address) of the other sta software on your computer, however, and making it easy to install and con tion you'd like to link in, you just enter it, you are either a Sysop or User. figure . . . now that took some serious but there's a search feature to help, and As a Sysop (System Operator), you thinking and work. even a random mode. Search results are are expected to connect a radio to your read over the air to you by a quasi-syn computer, providing infrastructure for thesized voice. Tune to the node or others to use. The Sysop can connect EchoLink repeater input frequency and, using either a simplex radio or a repeater, but Some time ago (September 2000), I DTMF tones, build the link and have fun I either way this role requires some com wrote about the W7DXX Remote Base, EchoLink can be very helpful for mitment and funding, as well as a fast a radio transceiver controlled over the emergency communications by voice, link to the Internet (and in some areas Internet. VoIP is yet another way to get much as WinLink 2000 can be for e- frequency coordination). "on the air" without a radio, although its mail. While local EchoLink stations Many of us will work with EchoLink in real value is its ability to link up widely might be out of commission from a fail the User mode. For this, all you need is separated radios. Two popular VoIP sys- ure of equipment, power, orthe Internet, a Windows® computer with a sound
Command Description Default
Connect Connects to a station on the Internet, based on its node number.
Table I- Some common DTMF commands in EchoLink. (Reproduced with permission)
44 . CQ . December 2004 Visit Our Web Site card, speakers, microphone, and an process; just follow the on-screen Internet connection. Your PC replaces prompts. Remember to select whether your radio, and you can link (and speak) you planto be a Sysop or User (you can to any other user, repeater, or simplex change later). radio that's on the system and not busy. As the installation ends, the system There's no RF path at your end. will start the EchoLink program and find The first step to getting onto the that you are not yet validated to the sys EchoLink system is to visit the EchoLink tem and start that process automatical website at
46 . CQ • December 2004 Visit Our Web Site The issue, in a nutshell, is this: Your Getting on the air involves simply If you want to learn more about the router and software firewalls (which, if picking a station and connecting to it. way VoIP works and is being used today you are a regular reader, you surely From the Sysop side, you log into by amateurs, pick up the book VoIP: use) are set up to block all data from EchoLink and connect your radio or Internet Linking for Radio Amateurs by entering any "ports" on your computer repeater to EchoLink, inviting others to Jonathan Taylor, K1RFD, who is also that are not specifically opened. This use it. Local users use DTMF tones to the author of EchoLink (ISBN 0-87259- helps prevent external attackers from connect and manage a QSO with anoth 926-4, $17.95, published by ARRL). It accessing your system. EchoLink re er EchoLink station, or distant users is a good book which explains the tech quires two ports, 5198 and 5199, to be connect into your system and their voice nology in a friendly, easy-to-read style open to incoming UDP data. Port is transmitted on your radio. Some basic and covers some of the finer points of Forwarding opens these ports and commands to connect to or find a spe setting up a station. directs the incoming data to a specific cific EchoLink "node," or to connect to computer on your LAN. That's why you a random node, are included with the need static IP addresses, so the router EchoLink application. Note that you Holiday Wishes knows which computer is which. Port really should be the operator of a That's all for this year. Next time I hope Triggering leaves these ports closed to repeater to link it into the system, or at to take a close look at a few HF data incoming data until a program (such as least have permission and authoriza modes, their performance and efficien Echolink) sends data our of those ports. tion from the repeater owner. A busy cy, as well as a new way of classifying Thus, until you start up EchoLink, the repeater is a poor candidate for linking. the signal quality of PSK31 contacts ports remain closed—a bit more secure. There are already too many users! using an "RSQ" report. If you have difficulty with this issue, I Before signing up as Sysop, I recom As is my custom this time of year, I again urge you to read the trouble mend becoming familiar with the system wish you and your family & friends the shooting documentation carefully; the as a user, which is in itself a lot of fun. very best for the holiday season, and solution really is in there. You just have Some statistics on EchoLink: Currently hope you enjoy a happy, healthy, and to find it. (10/04) there are 137,573 validated, prosperous New Year. This time of year After you get it working, connect to the licensed users, 49% of which are in the causes the world to think more about Test Server and set up your incoming U.S. They validate about 130 new users peace, and regardless of your person and outgoing audio quality. There are a per day. The top 10 countries are USA, al political and religious beliefs, I think few settings on the Tools/Setup/ Audio UK, Canada, Germany, Brazil, Japan, most of us can agree that living in peace menu, and you should try them all until France, Italy, Australia, and Spain. Some is one of the best ways to live. you find the best combination for "on-the- 35% of the users are in a country where air" sound quality for your station. English is not the primary language. 73, Don, N2IRZ
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