IRLP in Australia
This page has received hits since April 28 2001
This page describes IRLP (Internet Radio Linking Project) repeater networks, firstly from an end user perspective ("What can it do for me"?), and then touches on what's involved in getting IRLP up and running on a repeater, to provide local amateurs with access to IRLP's features.
What is IRLP?
IRLP is a sophisticated system for linking radio channels that was developed in Canada. IRLP uses Linux based software and a custom designed hardware interface to provide permanent and flexible links between distant locations. The links can be controlled by the end users through the use of DTMF tones. As most amateur equipment these days comes with DTMF as standard, this makes it easy for the average amateur to control the system. IRLP also includes security features to ensure that only listed gateways can take part in an IRLP network. It is not possible for an unlicenced person to gain access to the system via the Internet.
IRLP in Australia as at April 2001.
At the time of writing, there were only two IRLP nodes in Australia, namely VK2RBM, west of Sydney and VK6RNC in Perth. There were also a handful of nodes in planning and some expressions of interest from other areas. It is these expressions of interest that I'd like to see evolve into fully fledged nodes. My feelings are that IRLP and what it does is not yet fully understood. In my case, it took a visit to Sydney and spending some time on VK2RBM and with the operator of the IRLP link there to fully appreciate the system. What follows is a review of my experiences while in Sydney and then some information on what it takes to get an IRLP node up and running.
The concept of IRLP is well suited to Australia's sparse population, where major centres can be inexpensively linked at low cost. However, it does require some minor changes in some areas to suit our conditions. The main issue is that low cost, high speed links aren't as common as they are in North America. Nodes in more remote areas are likely to be limited to using a dialup modem. This necessitates the use of GSM compression on these links, and precludes these nodes from taking part on existing reflectors. To enable Australia wide nets to be setup, a GSM reflector will need to be setup so all Australian nodes can utilise it.
Note - By September 2001, there were over a dozen registered IRLP nodes in Australia, with around 25 expected to be operational by the end of the year. The GSM reflector never eventuated, as broadband Internet connections have since become far more commonplace in recent months, negating the need to use the GSM CODEC. This may change as nodes push further into the bush.
IRLP on VK2RBM, April 2001.
In late April 2001, I was in Sydney for work reasons, and took the opportunity to get acquainted with IRLP while I was up there, and obtained a copy of the DTMF access codes for the current list of nodes. As I was working in the city, reception of VK2RBM was difficult at times, and I was just beyond being able to access the repeater from ground level, (where the level of interference from pagers was less severe). This limited my ability to use the system severely, but still allowed a lot of listening time while travelling to and from work. IRLP was a bit different from what I originally expected. I had envisioned more or less permanent links, like hard wired or UHF links, only over much longer distances. Instead, it turns out that IRLP is more like a cross between radio and the telephone system. Users choose which node they want to access from those available (like looking up a phone number in a phone book). To access the node, they type in the 3 digit node address on their DTMF keypad, followed by the link command. If the connection is successful, the repeater transmits a short greeting message from the other node then enables the link. From that point, the repeaters are linked and anyone can access them from either end. To unlink, users only need to send the node number, followed by the unlink command. A confirmation message is heard when the link is shut down. Links also time out and disconnect after a period of inactivity, so the default condition is that each repeater is on its own and not linked to any IRLP node.
As previously mentioned, I also got to visit Peter, VK2YX, who runs the IRLP node on VK2RBM. Peter described his experiences with the system and showed me how it works. He also noted the huge increase in repeater activity from local users, which I noticed as well, even when there were no links active. We also discussed the possibility of nodes in other parts of Australia, as IRLP, with some minor changes is well suited to the widely separated population centres in Australia. Interestingly, it also turns out that IRLP users are also using the repeater as a liaison point, to arrange operation on other frequencies such as HF, which is another positive side effect.
Towards the end of my stay in Sydney, I finally got a chance to have a good turn at the system. From a high point in the southern suburbs, with a SWL friend looking on, I fired up a link to Reflector 2 in Denver, Colorado, which had several repeaters from the USA and Canada linked in at the time I linked VK2RBM in. Through the system, I worked a couple of VEs, before having to close the link to allow a couple of locals to sort out some navigational problems. :-) My SWL friend was somewhat more than impressed at the power and clarity of the system. The overseas stations were as clear as the locals.
Basically, I was more than impressed with the system. IRLP exceeded my expectations by a long margin, and the stability and reliability of the system was evident as well. I didn't hear one single hiccup in the several hours of listening spread over 6 days, unlike the IPhone system of 3 months earlier, which had several hiccups within a few hours of operation.
What can IRLP links be used for?
What can one do with an IRLP link? Why bother putting one in? All this Internet linking and DTMF controlled connections is all starting to sound less like ham radio and more like telephone toys! As it turns out, IRLP has many uses.
Firstly, and most obviously, an IRLP link is a reliable (to the limits of modern PC hardware and the Internet) connection between selected points around the world. This reliable link has many potential purposes for amateurs, including:
It's also interesting to note that an increase in local VHF activity has occurred in the Sydney area, since the installation of the VK2RBM IRLP node, with several amateurs dusting off their old 2 metre FM rigs to use on the link. Most of this increase has occurred on VK2RBM itself, where there have been lengthy periods of activity with the link not being activated.
So you want to run an IRLP node?
Running an IRLP node isn't as difficult as it might first seem. Firstly, you need the following prerequisites:
Some people consider IRLP as a means to get traffic to your repeater. While I can say activity on VK2RBM has exploded since the installation of IRLP, the primary purpose of IRLP is to enable reliable and cost effective long haul communications. IRLP nodes have many uses from allowing contact with distant friends to liaison for HF contacts or long distance experiments. IRLP is also a user driven system. It is the users who decide when to link to what node (via DTMF commands). Likewise, users can also decide not to link to an IRLP node at all, if they want to chat locally. IRLP puts the power in the hands of any amateur who has a DTMF keypad (most modern VHF/UHF rigs). The IRLP hardware on VK2RBM had no problems deciphering my ham fisted DTMF keypresses, even under poor signal conditions.
IRLP in VK3!
Currently, there are a number of IRLP nodes operationg or under construction in the Melbourne area, and a couple of nodes in regional Victoria. However, many country areas are still not serviced by IRLP yet. As I have expertise in Linux and some experience with Internet repeater linking (operator of two IRLP nodes, experience with other technologies such as IPhone, and developed a technique for temporary linking of repeaters to node controllers), I'm willing to offer assistance to any serious bid to get a system up in the Melbourne area. If you'd like assistance, a presentation (about 90 minutes duration) and live demo of IRLP at your club, or just some information for yourself or your club, please drop me an email to email@example.com.
Please not that a live demonstration of IRLP can now be arranged at your club, even if there is no active IRLP node in your area - an IRLP node can be setup temporarily for the demo. If you'd like to have a demonstration node for a few hours, you will need to have a reliable Internet connection available (dialup modem will be OK for demo purposes, though broadband is preferred), and be able to provide access numbers, login and password details so I can connect to your account.
The following links contain more information on IRLP.
VK3RGL - Victoria's first IRLP Node. Keep up with the latest on the new system being installed.
VK3JED IRLP Node. A system dedicated to IRLP development and promotion.
IRLP (Internet Radio Linking Project). The home of IRLP
VK2RBM IRLP Node, one of Australias first!