100th and 60th Anniversaries

摘要

One hundred years ago while an undergraduate at Columbia University, Edwin Howard Armstrong invented and patented the regenerative circuit which allows a signal to be amplified many times by the same vacuum tube or other component. He followed this up with the superheterodyne receiver in 1918, and the super-regenerative circuit in 1922. Perhaps most notably, he was also the inventor of frequency modulation which, of course, remains the basis of today's FM radio.