Internet Linking Roundup
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Internet Linking is exploding!
Internet linking is one of the fastest growing areas of our hobby, with hundreds of linked systems and tens of thousands of hams using Internet links around the world. Internet linking has come a long way from the early experiments of the 1990's, which involved a lot of manual intervention, to today's range of reliable, easy to use systems.
What sorts of systems are there?
There is a wide variety of linking systems in use. Some feature highly secure links, others feature access directly from your PC. Some systems offer DTMF control to radio users and many other features. Every system is different, and each has its following. In fact, one of the hardest things for new users of Internet linking to work out is what is fact, and what is uneducated opinion from people who have only used one or two systems, or have a strong preference for a particular system. This page is an attempt to portray each system in an objective light, and let the end user decide.
Internet linking systems range from shareware and commercial Internet telephony software connected to radios, right up to complete, specialised hardware/software linking systems with remote DTMF control and a host of other features. The sections below will look at each major system.
IPhone was, in many ways, the system that got Internet repeater linking off the ground and into the general amateur population. IPhone itself is a (now unsupported) shareware Internet telephony application which was used by amateurs as a linking medium. At one stage, there was even an attempt at securing IPhone from public access, through a companion application called RptrLink, which authenticated people against the QRZ database, before letting IPhone make the link.
IPhone offered both point to point and conference room capabilities. Because IPhone was an Internet telephony application, it also allowed direct PC access to the system. Radio links were VOX controlled, and required that a hardware VOX unit be added to the transmitter, if there wasn't already a VOX in the radio. While IPhone worked, the application was prone to instability, and the VOX required a but of tweaking.
IPhone is now considered obsolete, as it is no longer supported by Vocaltec, and the conference servers have been closed down. There are plenty of alternative systems for prospective link operators to choose from. I mentioned IPhone because of its historical significance, and the fact that it led to the development of the more specialised systems which follow.
Internet Radio Linking Project (IRLP) - http://www.irlp.net
IRLP was conceived in the late 1990's by David Cameron, VE7LTD, to overcome what he saw as the major deficiencies in IPhone, which were the instability of IPhone and its Windows operating system, the lack of security on IPhone based networks and the lack of end user control of the links themselves.
IRLP is designed as a secure, robust and very flexible Internet linking system. Unlike most other systems, it is designed to prevent direct access to linked systems from the Internet. At the node level, PGP cryptographic techniques are used by the nodes to authenticate each other. The only way to access IRLP is via a connected radio gateway, or node as they are known. IRLP connections are initiated by the end user by keying DTMF commends from their radio. These commands allow control of link connection and disconnection, as well as any other extra facilities added by the local node owner. IRLP offers both point to point and "reflector" (IRLP speak for a conference room) connections. To maximise control of the radio, IRLP uses an interface board between the computer and radio to pass COS, PTT and DTMF signals.
Unlike other Internet linking systems, IRLP runs under Linux, which gives it extreme stability. In fact, ISP and repeater problems are more common than node failures. The use of the Linux platform also offers a number of other benefits to node owners, such as automatic updates of both the operating system and IRLP software (no more downloading the latest and greatest, you already have it!), and a very high degree of customisation. Many IRLP node owners have written and shared scripts which do things from reporting whether a link is up or not, to a talking clock, to on demand weather beacons, random node callers, news broadcasts and parrot repeaters. There are even scripts which allow node owners who are on modems to dial their Internet connection if it goes down, by remote DTMF control! As for the IRLP software itself, it is constantly under development and there are frequent enhancements, which are released to the IRLP community via the automatic update mechanisms discussed above. I have developed experimental control scripts to allow node owners to choose from a wide array of codecs to suit a specific situation and allow users on remote nodes to trigger scripts via DTMF commands. These are examples of the extreme flexibility available with IRLP.
For those prospective node owners nervous about taking the Linux plunge, there is excellent support from the IRLP installation team and the general community of over 600 node owners. Everyone else need not worry about the Linux issue. Your sole interface with IRLP is your DTMF keypad - nothing could be simpler than that! :-)
Some people have labelled IRLP as a "secret society". Nothing could be further from the truth. It is true that IRLP node owners are asked to refrain from discussing control specifics while linked to another node, but the node numbers themselves are available for all to see at http://status.irlp.net, and it is up to each node owner whether they want to leave their system open access or add extra access codes. On a similar note, some claim that IRLP is closed source. This is only partly true. There are a handful of binaries in the system which are closed source (but have simple interfaces and/or are well documented). However, the majority of IRLP is written in bash shell scripts, which the node owner can directly read and modify.
SWLs can also get their taste of IRLP. There are streaming audio feeds of some of the reflector traffic on the Internet, which can be monitored using Winamp or your browser.
To dispel more of the strange myths surrounding IRLP, visit http://fudbuster.vk.irlp.net.
In summary. If you want to offer a secure, stable and flexible RF only link in your area, and don't mind learning a bit along the way, then IRLP is for you.
iLINK - http://www.aacnet.net and EchoLink - http://www.synergenics.com/el/
iLINK was born in May 2001, when Graeme Barnes, M0CSH, released the first version of his Windows based Internet linking system, to provide a Windows based alternative to IRLP, with the added feature of direct connections from the Internet. Since then, iLINK has grown to the point where there are more than 10,000 registered users. iLINK has come a long way since its initial release.
In mid 2002, a new client program, EchoLink. written by K1RFD, arrived on the scene. Written to be compatible with iLINK, it offered several features which the original iLINK software didn't have, and EchoLink rapidly became popular. EchoLink also offered a simple means to interface a radio to the software, using a home brew interface similar to those used for PSK-31, SSTV and other computer generated modes, making gateway operation more attractive.
Some weeks after EchoLink's arrival, the iLINK and EchoLink server networks were split. While this split was intended to give people choice in whether they wanted to interace with some of the extra EchoLink features, the net result was that the iLINK users moved to EchoLink, and iLINK has very little activity.
In recent times, several amateurs have started work with the iLINK/EchoLink protocols and have written some open source implementations of EchoLink conference server and client software. The conference server, called thebridge, though very new has proved to be extremely robust. It runs on almost any Unix like system, as well as Windows.
EchoLink has a couple of things in common with IRLP. Firstly, it allows radio connected nodes to be controlled by DTMF commands. Secondly, it uses a dedicated hardware interface board between the radio and the computer. However, at this time, the hardware control is one one way (PTT only). The received audio is still sampled by a VOX routine in the EchoLink software. Unlike the original iLINK sysop software, EchoLink also supports hardware COS detection (like IRLP) and simple PSK-31 style radio interfaces.
EchoLink also supports both point to point and conference connections. There (currently) are no restrictions on which stations can call which. Computer based users can call other computer based users, or they can call RF links and get out on air. Similarly, RF users can key in a computer user's index number and call them from the mobile. The computer interface is, for the most part, simple and well laid out, and offers quite good audio quality.
On the security front, when a new user registers on the EchoLink network for the first time, they are denied access until their callsign is verified as being legitimate. Once verification is successful, then the user is issued an index number, and can log into their account from other PCs using their index number and password. There has been debate in the amateur community about the degree of authentication deemed necessary (and whether the above is sufficient) for computer access to linked systems.
EchoLink's computer access is a mixed blessing. On one hand, it allows one to experience Internet linking without having to setup a gateway in their local area. However, I also find it annoying being called by other computer based users and getting interrupted. When I was using iLINK, I used to only run it to make a call. Now, I run an EchoLink gateway, so callers can try their luck on the radio here.
EchoLink doesn't support SWLs (except on scanners within range of a gateway). There are no streaming audio feeds of conference rooms that I know of.
In summary, EchoLink offers a relatively simple way to setup an Internet link, with support for direct connections, as well as DTMF controlled RF links. I have been running EchoLink as an RF gateway for some time. It is a well behaved and stable system with good audio quality, and a good interface for both PC based and RF users. EchoLink is also under active development by both the original author and open source developers, and is the only system at this time which supports multiple platforms. The new conference server software gives EchoLink the same scalability as IRLP reflectors, enabling large nets (limited only by available bandwidth) to take place on the system.
eQSO - http://www.eqso.net
eQSO was written in 2001 to fill the void left by the demise of the IPhone conference servers. Formerly known as the M0ZPD Internet Gateway, it was renamed to eQSO in early 2002.
eQSO is quite different to IRLP and iLINK, and is based around the IPhone style conference room operation. eQSO only offers conference room facilities, and there is no end user DTMF control. Like IPhone (and iLINK), direct PC access to the eQSO servers is permitted. There is also a companion application that allows the user to browse the list of available servers so they can choose a conference room of interest.
eQSO offers the widest range of options for interfacing to a radio, from plain VOX right through to full hardware PTT and COS interfacing. The VOX in eQSO is very well designed, with independent threshold and "quiet" level settings, which enable it to be easily configured to minimise the risk of false triggering, while preventing dropouts between words. Once setup, the VOX is surprisingly reliable, and its easy to get a link up. The audio quality of eQSO is not as good as iLINK or IRLP - often it has a soft "ticking" sound. However, it tends to use less bandwidth than the other systems, so it is a good choice where phone lines are poor.
Like iLINK, eQSO's computer interface is easy to use. The Linking version also offers courtesy tone and Morse ID as well, with a range of checkboxes to control the applications behaviour.
eQSO has no authentication mechanisms, and it, like IPhone, relies solely on the "honour system". SWLs are allowed to sit on conferences, and there are conferences without RF links, to enable hams and SWLs to interact. However, despite the lack of authentication, there are mechanisms for server owners to kick off unruly users.
The conference nature of eQSO makes its computer access mode less "intrusive" than that of iLINK, and you can easily sit on the side and monitor a QSO. This makes it especially suitable for monitoring.
In summary, eQSO is an easy to setup and pleasant to use conferencing application. Good for distributed nets where the RF gateways are attended, as well as for ad-hoc and temporary links.
HamLink - http://www.hamlink.com
HamLink was first released in July 2002, after a long period of development. On the surface it looks similar in concept to EchoLink, but it offers a few extra features, most notably, a voice mail system and a structured system for accessing amateur news bulletins.
At the time of writing, HamLink is still in its early stages of deployment, after a few teething problems, and hasn't been reviewed at this time (I prefer to review at a later stage to give the system a fair go), once there is a bit more activity on the system.
There are a number of linking systems available to the amateur these days. Each system serves a slightly different purpose - the question of which one is "better" is best left to the person installing the system. However, I will add a few comments. Technically, IRLP is the most sophisticated system, and there has also been a lot of work done in defining what makes a good IRLP node (not only the system, but how one should interface the radio for best results). The support networks of the other systems would do well to follow IRLP installation standards, as they are basically good engineering practice, and will improve the useability of _any_ of the systems discussed here. In other words, a system designed to meet the IRLP recommended standards will work well on HamLink, EchoLink or eQSO. The overall quality of a VoIP linking system is as much dependent on the design and implementation of the PC-radio interface as the linking software itself. All systems would do well to encourage best practices for the implementation of RF links. This, much more than the system used, contributes to the overall satisfaction of using a linked system.
Because IRLP is a true "wormhole" system, a lot of Government regulatory bodies are somewhat more comfortable with it, and it may be easier to get an IRLP node approved for unattended operation, or at all. However, in countries where Internet linking is _not_ allowed, or is heavily restricted, iLINK or eQSO can still be used from one's PC. One big deficiency with the current generation of PC based systems (with the exception of EchoLink) is they are not cross platform, so only Windows users can access them via their PC. This doesn't matter to RF users, and has no effect at all on IRLP, since that system only allows RF access.
Hopefully by this stage, you're now in a better position to decide which system is for you! :)
For the record...
I have been involved in Internet radio linking since early 2001, when I started using IPhone. In June 2001, I installed the first IRLP node (node 630) in Melbourne, Australia, and followed that up with my development/promotional system, node 639. I started using iLINK as a PC based user in June 2001, and also run an EchoLink RF gateway, node 22497 (VK3JED-L). I have also been actively following eQSO, and have had an experimental eQSO RF gateway running here from time to time. The whole linking system is standardised here (to IRLP V2.01 specs - only because that's what the radios are setup for), in order to make it easy to connect any radio to any linking system. I can currently support linking on 6m, 2m and 70cm.
I'm actively involved in IRLP software development and EchoLink software testing.
The systems used for testing are as follows:
IRLP - P200 running IRLP standard Red Hat Linux 6.2. 96 MB RAM, 4GB HDD, SB32 AWE soundcard. This system will also be used for testing the EchoLinux EchoLink client application.
iLINK, EchoLink and eQSO - Athalon XP 1600+ running Windows 2000. 512M RAM, 40GB HDD, SB Live! 256 soundcard and AC-97 onboard sound chipset.
thebridge EchoLink compatible conference server software has been tested on a Cyrix P200+, 64MB RAM running Red Hat Linux 7.3.