It was one of the most important inventions in the history of mass communications. But for reasons unknown, this groundbreaking invention languished in a patent office for about 11 years before it finally saw the light of day, said Karl Astrom in a special presentation as part of CSL's Golden Anniversary lecture series. The invention was the negative feedback amplifier, a control system that made it possible to overcome one of the major hurdles of long-distance communicationhow to amplify a person's voice without amplifying the noise and distortion that came with the signal. Without it, there would have been no long-distance telephone and television networks. Astrom, professor of automatic control at the Lund Institute of Technology in Sweden, cited the negative feedback amplifier as one of the landmarks in control system history.
Control systems are all around usin our cars, airplanes, power generators, even our CD players.
They are widely used and hugely successful, he said. But control systems seldom get public attention, except when one of them fails and disaster strikes. They typically remain hidden, tucked deep inside the hardware. In his CSL Golden Anniversary talk, Astrom traced the history of automatic control systems in three primary areasindustrial process control, vehicle control and communication. In vehicle control, for instance, Astrom zeroed in on flight control, beginning with the Wright Brothers' landmark flight at Kitty Hawk, North Carolina, in 1903.