Abstract
MR. H. R. HABBOTTLE of the Post Office Research Station read a paper on February 4 to the Institution of Electrical Engineers describing an instrument for measuring the disturbing effect of induction from power lines on telephones. During a meeting of the Commission Mixte Internationale held at Dollis Hill, the delegates made comparative measurements of four different types of disturbances by the American, German and valve voltmeter methods. It was agreed that the last-mentioned should be developed and that the precise specification for the actual instrument should be determined by the Comite* Consultatif Internationale (the C.C.I, for telephonic communications at great distances). It has been agreed internationally to call an instrument of this type a psopho-meter. The latest proposals are explained by the author. He states that from comparative measurements of the induction from the Midi Railway, which is supplied with power through mercury arc rectifiers, to the overhead communication lines of the French administration, the results obtained by using the psophometer fully justify this method of making noise measurements. The British Electrical and Allied Industries Research Association has publisheda pamphlet M/T 38 describing the method of constructing a psophometer. About a year ago, a commercial model on similar lines was constructed by the General Electric Co. at Coventry. Others have been made by Siemens and Halske in Germany, by the Administration and Ericssons in Sweden, by Standard Telephones and Cables in England and by the American Telephone and Telegraph Co. At the same meeting, a paper by Dr. A. H. Davis entitled “An Objective Noise Meter for the Measurement of Moderate and Loud, Steady and Impulsive Noises” was also read. The difficulties experienced were surmounted by adopting a technique in which the noise and the reference note are listened to alternately.
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Telephone Circuit Noise Meters. Nature 141, 681 (1938). https://doi.org/10.1038/141681b0
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DOI: https://doi.org/10.1038/141681b0