Back in December of 1996, I was flipping through the many magazines at the UBC club. I came across the December 1996 issue of the QST Amateur Radio magazine that had the words "Link your repeater to the Internet" written on it. I had a quick read through the issue and found a well written article by James Millner, WB2REM entitled 'A New "Band" for Your Radio'. At first glance, I was hooked. What more could I ask for? It was a combination of the two hobbies that I love the most.
My first connection used VocalTec's iPhone. The original article by WB2REM used iPhone to send the voice over the internet. I did have some problems with the software, mainly in the fact that iPhone is not very stable nor is it controllable. After running iPhone for close to 6 months on active connections to Vernon BC and St. John NB, I decided that the stability and control were key. That is when I started getting into using LINUX as an operating system and Speak Freely as a client/server.
Speak Freely is a voice over IP client/server package that transmits live audio (i.e. speech) over the internet with surprising clarity and quality. This program basically allows any two parties anywhere on the internet to have a voice conversation with each other in real time. My objective, and the objective was to use this program to link to radio equipment so that voice connections can be made without the operator being tied to a computer. This will allow hams from all around the world to talk to one another without relying on radio conditions.
Many amateurs have raised a very important question regarding this kind of system; What if non-ham users start connecting to ham repeaters? With all the experienced "hackers" out there, I can not say that this system is totally bullet-proof. I have designed safeguards into my software to reject calls from "non-hams".
The main hurdle I had to overcome was the interface between the computer and the radio. From my experience with VOX circuits under iPhone, I decided that I HAD to find an alternate way to start sending audio and to key the radio when audio came in (from the internet side). Since the source code for iPhone was not available, I had to look for an alternative. I was told about Speak Freely by a friend of mine, and I decided to give it a try.
I played around with modifying the source code for several weeks and finally came up with some code that works. The software starts the link radio transmitting once packets have been received over the internet and unkeys once they stop coming in. The software starts sending audio once a signal is received and continues to send it until the signal is removed. This logic control is performed using the parallel port of the computer and all the computer chips are on a separate interface controller board. I have designed this board, and I am building them and selling them at cost to promote the project.
The whole system is DTMF controllable. The control codes lie imbedded in a separate program that reads the DTMF tones from the decoder chip (located on the interface controller board) and activates various parts of the software. DTMF codes are used to enable/disable linking, open/close links and set identifiers. Every site will have the ability to connect direct to any other site(s), either using direct connections or reflector sites.
So in a period of 8 months, I switched from a piece of software and hardware that someone else built, to my own creation which solved all the previous problems I was experiencing! Ever since the IRLP started, I have never again looked to iPhone or Windows for an option in the system.