RADIO

Wireless telecommunication took off after Marconi demonstrated Morse code transmission over several kilometres in 1896. It was immediately adopted for maritime use.

Early receivers used crystal detectors that were difficult to adjust. Transmitters and receivers got better in the early 1920s after the invention of radiotubes. Receivers evolved from TRF (tuned radio frequency) to superheterodyne, from AM to FM, to satellite, to digital and SDR (Software Defined Radio) today.