. Practical wireless telegraphy; a complete text book for students of radio communication . HIIC SJiJria taaorimo A typical chart* of the relative strength of signals received at different hoursof the day from the Marconi station at Ketchikan, Alaska, at the receivingstation at Astoria, Ore., is shown in Fig. 239. These readings were taken on aMarconi audibility meter. —H *Curve A, Fig. 239, shows the signal audibility throughout the 24 hours of the day from Ketchikanto Astoria. Curve _S shows the intensity of atmospheric electricity. It is interesting to note the distinctrise in both the sign
. Practical wireless telegraphy; a complete text book for students of radio communication . HIIC SJiJria taaorimo A typical chart* of the relative strength of signals received at different hoursof the day from the Marconi station at Ketchikan, Alaska, at the receivingstation at Astoria, Ore., is shown in Fig. 239. These readings were taken on aMarconi audibility meter. —H *Curve A, Fig. 239, shows the signal audibility throughout the 24 hours of the day from Ketchikanto Astoria. Curve _S shows the intensity of atmospheric electricity. It is interesting to note the distinctrise in both the signal and static intensity near to midnight and the distinct drop during the eariyhours of the morning. The rise of the peak is found to occur at approximately the same hour jnobservations taken over several months duration. PRACTICAL RADIO MEASUREMENTS. 219. i^QO 500 400 fiOO 900 500 600 70Q WAVE LENGTH IN METERSFig. 240—Curves Showing the Effect on the Radiated Wave By Progressive Reduction of the Coupling at the Oscillation Transformer. 182. Tight and Loose Coupling.—The adjustment of the coupling ofan oscillation transformer is important because if the primary and secondaryare closely coupled, oscillations of two frequencies occur in the antenna circuitas shown by the curve A, Fig. 240. If the coupling be reduced- (by drawing the primaryand secondary windings apart) and a second resonance curve obtained, the two frequenciestend to merge into one as shown by curve B, Fig. 240. Further reduction of couplingbrings about the condition shown by curve C in which the energy radiated is confined topractically a single frequency of oscillation. The wave C may be of greater or lesseramplitude than waves A and B, according to conditions.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
