. Practical wireless telegraphy; a complete text book for students of radio communication . The functioning of the heterodyne* re-ceiver is based upon the interaction of alternating currents of two frequencies insome part of the receiver circuits. For example, if an alternating current of 50,000 cycles per second flows through a givencircuit, and there is superposed on it another current having frequency of 49,000 cycles persecond, a beat current will result having a frequency equal to the numerical differenceof the two applied frequencies or cycles per second. The same frequency would b
. Practical wireless telegraphy; a complete text book for students of radio communication . The functioning of the heterodyne* re-ceiver is based upon the interaction of alternating currents of two frequencies insome part of the receiver circuits. For example, if an alternating current of 50,000 cycles per second flows through a givencircuit, and there is superposed on it another current having frequency of 49,000 cycles persecond, a beat current will result having a frequency equal to the numerical differenceof the two applied frequencies or cycles per second. The same frequency would beobtained by superposing a current of 51,000 cycles upon another current of 50,000 cycles; infact, in any case, the frequency of the beat current could be the difference of the twoapplied frequencies. By adoption of this principle we are afforded ready means for making audible undampedoscillations from a given transmitter at the receiver. One method is shown in Fig. 291, •Abroad, this receiver is called the local interference receiver. RECEIVERS FOR UNDAMPED OSCILLATIONS OR WAVES. 279. where the receiver circuits are indicated by L-1, L-2, the crystal rectifier D, etc. An «n-damped oscillation generator consisting of the D. C. arc gap A, B, the variable condenser Cand inductance L are shown at the base of the drawing. By means of this generator, a steadystream of oscillations is supplied to the aerial system through the coupling coil L-3, thefrequency of which can be altered eitherby the condenser C or by the induct-ance L. Now, if the receiving tuner, for ex-ample, is tuned to the wave length of6,000 meters corresponding to an oscilla-tion frequency of 50,000 cycles per second(which may be the wave length of a giventransmitting station), and the arc genera-tor adjusted to generate oscillations at afrequency of 49,500 cycles per second, abeat current of a frequency of 500 cyclesper second will flow in the circuit of thereceiver where it will be rectified by thedetector, D, a
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
