Which was the world's first transmitter of sound signals and could transmit voice and music Fessenden was able to implement this idea of his in 1906 as well … and organized several sessions of music transmission over several tens of miles Unfortunately, at that time it did not arouse any interest among industrialists   and the idea of broadcasting voice and music over long distances became relevant only after the end of the First World War and it was implemented no longer on machine transmitters and alternators, but on transmitters with electronic radio tubes Detector radio receiver It has no amplifying active elements, so it has one very important advantage over other types of radio receivers… .. does not require a power source and uses only radio signal energy Its second advantage is the possibility of reception not only in telegraphic mode, but also signals with amplitude modulation of sound frequency and voice And it already has an antenna circuit and the ability to tune to different reception frequencies With the invention of the radio tube and the creation by the American Lee De Forest of the first amplifying radio tube triode ("Audion")  in 1906 … New types of radio receivers began to appear - direct amplification, regenerators, and what is especially important - superheterodynes … Direct gain receiver It is quite debatable, but Leide Forest's radio receiver can be considered the first receiver of direct amplification because it amplified the signal before decoding, albeit weakly.