Wireless Telegraphy and Telephony

WIRELESS TELEGRAPHY 129 It may now readily be realized that there are long pauses between the sparks when there are no oscillations in the aerial, and, consequently, no electromagnetic waves passing between the transmitter and receptor during those periods. The wavy line, C, represents the vibrations of the human voice when producing speech. Part of it has been repre- sented by a continuous line, and part by a dotted line. The portions represented by the dotted line occur when there are no oscillations in the aerial, and consequently these Fig. 143.—Diagram illustrating the reason why damped oscillations will not carry the voice. portions are not transmitted. The continuous portions are the only ones reaching the receptor. Literally, there are “holes in the voice,” and the result is a jumble of sounds, sometimes bearing a resemblance to speech, but usually un- translatable. The fault lies in the method of producing the oscilla- tions which are damped and therefore do not exist continu- ously. If they could be made to keep on swinging and at a sufficiently high speed so that their tone would be in- audible and not confuse the speech, the problem would be solved. In other words, three things are necessary for the successful operation of a wireless telephone. i. A means of producing and radiating a stream of un- dampened electrical waves sufficiently continuous to trans- mit the upper harmonics of the voice, on which the quality and recognition of the speech depends.