The FAA has all sorts of requirements. What do you expect from a government agency? One of them is that your transponder needs to be certified every two years. So this guy brings out his equipment and tests it. The tripod is holding a receiver antenna and the instrument sitting on the table is reading the output. The actual transponder antenna is the little three inch whip just to the right of the tripod. Anyway, my transponder was just fine. Good for another 24 calendar months.