air traffic control airband aircraft emergency frequency alaska amateur amateur radio emergency communications amateur radio frequency allocations amateur radio homebrew amateur radio international operation amateur radio license amateur radio licensing in the united states amateur radio operating award amateur radio operator amateur radio repeater amateur radio station amateur television american morse code american radio relay league amplitude modulation astronaut australia automatic packet reporting system automatic link establishment automatic vehicle location base station belgium building business band cqd call sign callbook canada chinese telegraph code circuit diagram coast radio station communication computer-assisted dispatch computer network contesting continuous wave d-star dx-pedition digital echolink electrical telegraph electronics engineering etymology of ham radio fade margin family radio service federal communications commission frequency modulation general mobile radio service germany global positioning system government hamfest heliograph high speed telegraphy high frequency hill history of amateur radio history of radio hobby india inductor industry international amateur radio union international space station international standard book number international telecommunication union internet radio linking project italy landline link budget list of amateur radio magazines list of amateur radio modes list of amateur radio organizations mandatory frequency airport marine vhf radio maritime mobile amateur radio microwave mobile radio modulated continuous wave morse code morse code abbreviations morse code mnemonics mountain multi-use radio service new york city new zealand association of radio transmitters oscar oman on-off keying online computer library center open directory project packet radio professional mobile radio prosigns for morse code public services push to talk qst q code quik call i radio radio amateurs of canada radio society of great britain radio frequency radio repeater radioteletype rayleigh fading sos satellite science selcall shortwave signal-to-noise ratio signal lamp single-sideband modulation single frequency approach skywarn slow-scan television south african radio league specialized mobile radio spurious emission switzerland telegraphy television tone remote transceiver trinidad and tobago trunked radio system two-way radio types of radio emissions unicom ultra high frequency united kingdom united states vacuum tube vehicle registration plate vintage amateur radio voice procedure wabun code walkie-talkie watt wireless wireless institute of australia wireless network yugoslavia z code