You also have to be careful about modifying radios and antennas -- some radios are certified with specific power outputs and particular antennas. Changing those (such as adding a directional antenna) can void the certification. Sometimes changes can be made if the equipment is operated under a different certification (like the Amateur Radio service).
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http://www.uvs-international.org/uvs-info/Yearbook2009/081_Contribu...
There will be worldwide standards for UAS communications before too long.
A couple of FPV vendors have already had chats with the FCC, over equipment that does not meet acceptable standards that they were importing.