American Radio Relay League (ARRL) is the national association for Amateur Radio in the United States; and with more than 161,000 members, it is the largest organization of radio amateurs (“Hams”) in the world. ARRL's mission is based on five pillars: Public Service, Advocacy, Education, Technology, and Membership. By design, Amateur Radio has always been an open-source type environment with much of its equipment, tools, and technology being self-built and freely shared (by Hams).
For the first time, the ARRL has authorized a "Special Events" station to operate at the Southern California Linux Expo 2016 (SCaLE-14x) under the temporary call-sign of "N6S". In addition to demonstrating various aspects of radio communication, the station will highlight the synergistic relationship between Amateur Radio and the open-source community. SCaLE-14x participants are invited to come, see, listen to, ask about, and even operate!
For more information see http://www.arrl.org/ and http://www.arrl.org/what-is-ham-radio.