| 摘要 |
In speech communication systems e.g. utilizing wireless waves or transmission lines, comprising a transmitter and a receiver, the effects of audio- frequency interference (24), e.g. rustling or crackling in the loudspeaker of the receiver, are suppressed by the superimposition on the carrier of a speech- controlled low-frequency pilot signal coincidental with the superimposition of the speech signal (25), a switch (19) being provided in the audio frequency path for enabling the loudspeaker only in the presence of the pilot signal. The switch (19) is controlled by a receiver element (16) tuned to the demodulated pilot signal. <IMAGE> |
