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Show THE HOME IIO How to Make and Use !t fc &IlXgZ2--WIRELESS TELEPHONY In many ways, all the principles and laws of wireless telegraphy appl equally well to radio telephony, but, In other ways, there are great differences between the two. In the first place, the vibrations or waves sent out by the wireless telegraph transmitter are Interrupted as they are produced by the vibrator vi-brator of a spark coll and while the flow of the oscillations or waves may be so rapid that they appear as a steady stream, yet there is really a distinct pause after each one. j,. . , If a telephone transmit Nw . """"" SSmS" . vi ter and receiver wert, .. . ' attached to the ordl- ' , nary wireless lustra- Vi '" v v j "" ments used in te egra- phy, the sounds or vl-' vl-' bratlons of the voice would vary the puth of the electrical .- oscllla v.... tions and the pame va ' . .' nations would be. pro- VVv yv v s duced on the receiver. y'ySsysJv Bnt, owing to the fact that the waves are In- WI , s , terrupted and are not " v,svfcs, continuous, the wordf ' or sounds would be cut ' f'f.S" ! up Into sections which kvslyvvv. VVVv. Va j would be meaningless, vvwv , pT Y!'V'S, although such sounds f as music, bells, whltt- fi'l,6 ling, etc., might be rets L - ognlzable. In fact eotinds of this sort frequently have been heard ver ordinary wireless telegraph tele-graph Instruments. Hence It Is easy to see that the only reason why all sounds cannot be carried through space by ordinary wireless telegraph apparatus Is because of the Interrupted or broken waves, whereas, If these waves were continuous or were so incredibly rapid as to appear contiguous, the sounds they transmitted could easily be heard and nnnerstood. Therefore, the real fundamental key to successful wireless telephony lies In producing what are known as continuous waves and it Is to the perfection and control of such waves that radio telephony owes much of Its rupid advancement. The accompanying figures, Nos. 1, 2, 3, 4, 5, 0 illustrate Just how the Interrupted In-terrupted telegraphy currents and the continuous waves carry sounds. Thus, 1 represents the variations In vibrations In a certain word. 2, the Intermit- tent oscillations of the wireless telegraph sender and 3, the way the word would be broken ajid Interrupted by being transmitted by means of such Interrupted Inter-rupted waves. Figure 4, on the other hand, shows the continuous waves of the wireless telephone transmitter; 5, the sound waves of a word and 6, the waj the continuous waves. Interrupted by the words would appear. By study Ing these( diagrams you can easily see the difference between tbe word broken up as n figure 3 and flowing smoothly as In figure 6. It. must be borne in mlml, however, that whereas the sounds of the voice) of music, etc., cannot be satisfactorily sent or received by wireless telegraph Instruments, yet wireless wire-less telegrams can be sent to perfection, and can be perfectly received, over wireless telephone lnntmments. Indeed, the very best transmitting radiophone sets serve the best for sending telegraphic messages, the only difference being that for the former the continuous high frequency waves are used, whereas, when Bending code messages by telegraph, the waves are broken or "chopped" by suitable Instruments and a key which opens and closes the circuit. In using wireless telephony, Just as in wireless telegraphy, there must be two separate units known as transmitters and receivers and a transmitter can be used only for sending and a receiver for receiving. As the sending or transmitting trans-mitting apparatus df the wireless telephone Is fuT more complicated than the receiving Instruments, as the greatest Interest in wireless telephony lies In receiving re-ceiving the messages, songs, etc., sent broadcast from large sending stations, and as the receivers are very simple and easy to understand or to construct, we will put the cart before the horse, so to speak, and consider the receiving end of radio telephony before we take up the sending end. ' ' ' - v" ' |
