. The thermionic vacuum tube and its applications . Fig. 187. tube as a modulator, we are interested only in currents having P-i-Q frequencies lying within the range ^tt— . Hence, substituting Ztt (10) into (9), evaluating and dropping all terms having frequencies lying outside of tliis range, we obtain, J = aiei sin pt-\-2a2eie2 sin pt sin qt. (11) This expression represents a wave of varying ampHtude as shownin Fig. 188, the amplitude of the high frequency carrier^ wave ^ The word carrier is here used as a general term to indicate the highfrequency wave, which is modulated by the signaling w
. The thermionic vacuum tube and its applications . Fig. 187. tube as a modulator, we are interested only in currents having P-i-Q frequencies lying within the range ^tt— . Hence, substituting Ztt (10) into (9), evaluating and dropping all terms having frequencies lying outside of tliis range, we obtain, J = aiei sin pt-\-2a2eie2 sin pt sin qt. (11) This expression represents a wave of varying ampHtude as shownin Fig. 188, the amplitude of the high frequency carrier^ wave ^ The word carrier is here used as a general term to indicate the highfrequency wave, which is modulated by the signaling wave. It has also amore specific meaning in which it refers to the transmission of high fre-quency currents over wires. DETECTION OF CURRENTS WITH THE VACUUM TUBE 319 varying in accordance with the audio frequency wave impressedon the input of the tube. We can, for purposes of explanation, write equation (11) in the form, J = A sin pt(l-\-B sin qt) (12). Fig. 188.
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