History and idea
I'm an avid ARDF competitor, often a member of Croatian ARDF national team. During the last 15 years, there were some big improvements on analysis of orienteering and ARDF competitions. SportIdent and Emit electronic controls gave us instant electronic results on finish, and software like RouteGadget (married with GPS handheld devices) with its post-competition analysis gives competitors possibility to augment their experience by comparing results to others.
These enhancements were and still are welcomed, but the technology isn't cheap. Many tries were taken to make this available to wider public. The reasons are different - some want to use electronic controls in public areas, where's theft a big problem - expensive controls are a risk. Some want a robust electronic controls, which can survive elements of nature. Some want a cheap control card system which can be easily given away or cheaply bought in quantity.
My first experience with an electronic system was SportIdent on an ARDF competition in 1999. It was cool, it was great, it had everything we all wanted - except price. It was expensive as hell. Second encounter was with a system which used Dallas iButton control cards (chips, dibbers). It was made by Slovenian radio amateurs, put in a big (and I mean big) box, and had a nice addon - every control has an LCD display which gave informations when you "checked-in". In summer 2002, Emit was tested.
Sometime during the 2004, I started playing with micro controllers, Microchip PIC's. Using the experience, I knew the system isn't complicated. Checked the Internet, and found 3 similar systems: one was made as his Masters thesis by a guy at the same college as I was going, Joe Lee's system made in Britain, and Clifford Heath made a system for street orienteering in Australia. I first tried with the local guy, but unfortunately, it was a few years prior and he forgot all of small details. Clifford from down under was great help, he gave me an insight of how he overcame some of the problems. But this project fell in wrong time, and not until 2008 I could came back. We got some PIC protoboards on the job, so I could pursue this project. Even after getting the boards, it took me, working on and off, almost year and a half.
For starters, we need to know How electronic controls work (or could work)