In 1946 the Bell System made this short film to explain how its carrier system was used to transmit multiplexed voice and television signals.

There are still some of the original square concrete silo towers around, built at a time when a steel truss wasn't deemed stiff enough for microwaves, and today they are more likely owned by a tower company like SBA or American Tower. The delay-lens horns used in the original installations had limited bandwidth and later installations used steel towers and parabolic reflector horns. Eventually digital signals over fiber optic cable made the analog frequency division multiplex system obsolete.

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