. Practical wireless telegraphy; a complete text book for students of radio communication . ake undamped oscillations audible, we are compelled to break up theoscillations of either the transmitter or receiver into groups suitable for maximumresponse in the head telephone or to supply other means at the receiver to makethem audible. The receivers at present in use are: (1) The Poulsen tikker or chopper; (2) The Heterodyne system; (3) The Goldschmidt Tone Wheel; (4) The Regenerative Vacuum Valve (used as a beat receiver). The mode of func-A ni »^ tioning of these detectors is briefly described
. Practical wireless telegraphy; a complete text book for students of radio communication . ake undamped oscillations audible, we are compelled to break up theoscillations of either the transmitter or receiver into groups suitable for maximumresponse in the head telephone or to supply other means at the receiver to makethem audible. The receivers at present in use are: (1) The Poulsen tikker or chopper; (2) The Heterodyne system; (3) The Goldschmidt Tone Wheel; (4) The Regenerative Vacuum Valve (used as a beat receiver). The mode of func-A ni »^ tioning of these detectors is briefly described asfollows: The Poulsentikker interrupts the cir-cuits of the receivingtuner at a uniform rateper second {approxi-mately 300 to 600 times) ;the heterodyne system isbased upon the interac-tion of two radio-fre-quent currents in thereceiving aerial, resultingin the production of anaudio-frequent current inthe telephone circuit; theGoldschmidt tone wheelconverts the current ofradio-frequency {the in-coming oscillations) intoan audio-frequent currentand the regenerativebeat receiver employs. PHONES Fig. 289.—^The Simple Poulsen Tikker and Circuit. 278 PRACTICAL WIRELESS TELEGRAPHY. the vacuum valve as an oscillator at radio-frequencies to produce the heterodyne , combined with the well-known relaying action of the vacuum valve and its abiUty torepeat currents of radio-frequency, makes a receiver of unusual sensitiveness. 222. The Tikker.—In its commercial form the tikker consists of a com-mutator interrupter, the principal of which is shown in Fig. 289. A disc D mounted on the shaft of the motor M has a number of teeth filled in betweenwith insulating material such as fibre. The radio-frequent currents fiow from brush B to Athrough the disc which interrupts them from 300 to 1,000 times per second. The charge builtup in the condenser, C-1, by resonance with the aerial system discharges into the telephonecondenser, C-2 (Fig. 289), at regular intervals. Condenser C-2, i
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
