. Robison's Manual of radio telegraphy and telephony for the use of naval electricians . y, they simply tend to amplify orneutralize each other, depending on their relative phases. If not of thesame frequency, beats are produced as in music. For instance, if the trans-mitter has a frequency of 300,000 per second and the heterodyne 301,000,when one has made 300 vibrations the other will have made exactly301; so that they will exactly coincide once in each j-^ second, thus pro-ducing a third frequency of 1000 per second. Both transmitter andheterodyne have a frequency much greater than can be de
. Robison's Manual of radio telegraphy and telephony for the use of naval electricians . y, they simply tend to amplify orneutralize each other, depending on their relative phases. If not of thesame frequency, beats are produced as in music. For instance, if the trans-mitter has a frequency of 300,000 per second and the heterodyne 301,000,when one has made 300 vibrations the other will have made exactly301; so that they will exactly coincide once in each j-^ second, thus pro-ducing a third frequency of 1000 per second. Both transmitter andheterodyne have a frequency much greater than can be detected by thehuman ear, but their combination, producing a maximum of current inthe aerial 1000 times per second, can be read easily. The resultant 144 MANUAL OF RADIO TELEGRAPHY AND TELEPHONY. frequency would be the same (1000) if the frequency of the heterodyne,were 299,000. If it were 302,000, the transmitter would make 150 vibra-tions while the heterodyne made 151. They would coincide 2000 timesper second and the resultant note in the receiving telephone would havethat Fig. 90.—Fessenden.
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